The authors, Harris Bendel of Roskilde University’s PandemiX Center and Katarina L. Matthes of the University of Zurich’s Institute of Evolutionary Medicine, contend that contemporary studies of measles-induced immune amnesia face structural obstacles that historical data can circumvent. In high-income countries today, measles is so rare that the few people who contract it are inherently unrepresentative of the broader population, introducing severe selection bias. In regions where measles remains common, unequal access to healthcare complicates the assembly of reliable study cohorts. Observational studies in wealthy nations are further confounded by pre-existing conditions and differences in healthcare-seeking behavior, making it difficult to isolate the virus’s effect on subsequent mortality.

These methodological problems matter because the stakes of the debate are enormous. Some researchers have suggested that measles immune amnesia may have contributed to as much as half of all childhood deaths from infectious diseases in the period before vaccination. That figure traces back to a widely cited 2015 study by Mina and colleagues, who quantified the drop in non-measles infectious disease mortality in three countries before and after measles vaccines were introduced. The commentary’s authors argue that this approach falters when applied to Denmark, one of the countries in the analysis, because the data used came from a period when infectious disease mortality had already fallen to historic lows.

The numbers illustrate the problem starkly. In 1986, the year before the measles vaccine was introduced in Denmark, there were just 19 deaths from non-measles childhood infections; five years later, in 1991, there were 16. By the 1980s, many of the most significant killers of children, from tuberculosis to diphtheria, had already been largely tamed by sanitation, antibiotics, and other vaccines. Drawing conclusions about the pre-vaccine mortality landscape from such a late period, the authors argue, is unsuitable for estimating how much measles immune amnesia contributed to childhood deaths in earlier centuries, when the infectious disease environment was fundamentally different.

The commentary also points to a mismatch between the timing of measles infections and the timing of childhood deaths in historical populations. In early twentieth-century Copenhagen, census data show that childhood mortality was heavily concentrated in the first year of life. Yet the average age of measles infection in the city between 1907 and 1930, estimated from weekly case records, was 5.65 years. If immune amnesia were a dominant driver of childhood infectious disease mortality, one would expect deaths from other infections to cluster in the years following the typical age of measles infection. Instead, the age distribution of deaths from causes such as infant diarrhea and whooping cough barely overlaps with the distribution of measles cases, making it unlikely that immune amnesia was a major contributor to infectious disease mortality in historic Copenhagen.

The authors examined an annual report on epidemic diseases from Copenhagen in 1911, which breaks down deaths by cause and age group. Of 917 total deaths recorded, infant diarrhea accounted for 309, nearly all in infants under one year, while whooping cough killed 176, again concentrated in the youngest children. Measles itself caused 40 deaths. When the researchers fitted gamma and power-law functions to the age distributions of measles infections and non-measles deaths, the resulting curves showed little overlap, mirroring patterns produced by earlier simulation studies. The authors caution that more research at the individual level is needed to fully understand immune amnesia’s role in the pre-vaccine infectious disease landscape, but the population-level patterns raise doubts about sweeping claims.

Historical data, the commentary argues, offers a unique set of advantages for studying how measles reshapes the immune system. Countries such as Denmark and Switzerland preserve individual-level mortality and morbidity records from long before the first measles vaccine was introduced, from an era when infectious disease mortality was still high. Because measles is so transmissible, infection was nearly universal among people who survived childhood, which means infected cohorts are highly representative of the general population, even though the disease’s ubiquity makes it impossible to construct a control group of unexposed individuals. Still, the timing of historical outbreaks has been well documented through demographic research, allowing study designs analogous to modern cohort studies to be reconstructed for past populations. Detailed case and hospital records in the archives can even be linked to death certificates, enabling individual-level analyses of long-term consequences.

Studying the pre-vaccine era also decouples the analysis from a separate and contested theory known as non-specific vaccine effects, which holds that live attenuated vaccines provide broad immune benefits that reduce all-cause mortality in vaccinated individuals. Although the theory is not widely accepted, it exists as an alternative explanation for the observed correlation between measles vaccination and reduced mortality. By examining the association between measles infection and non-measles mortality in periods when no measles vaccine existed, researchers can more confidently attribute any effect to the virus’s immune suppression rather than to beneficial vaccine side effects.

The commentary highlights international efforts to make such research feasible, including the COST Action known as The Great Leap, which works to make individual-level cause-specific mortality data available for historical populations and to harmonize historical causes of death across countries and time periods. Such infrastructure is important because contemporary data alone are often insufficient to understand the long-term consequences of infectious diseases. Even studies directly comparing vaccinated and unvaccinated children suffer from substantial confounding, since the two groups may differ systematically in socioeconomic status, healthcare access, health-seeking behavior, and parental attitudes toward medicine.

The authors advocate for a systematic integration of historical demographic and epidemiological data into research on the long-term consequences of infectious diseases, using measles-induced immune amnesia as a case in point. Linking individual-level historical infection records with cause-specific mortality data could overcome the limitations of modern studies and open new avenues for investigating how infections shape health long after the acute illness has passed. With recent global outbreaks suggesting that the World Health Organization’s goal of measles elimination by 2030 is unlikely to be met, and with vaccine hesitancy causing measles to reemerge in countries that had previously eliminated it, understanding the full cost of the virus has never been more urgent. Unlocking the archives, the authors conclude, may fundamentally expand our ability to grasp how infectious diseases continue to claim lives well beyond the moment of infection.

Subject of Research: The use of historical demographic and epidemiological records to study the long-term effects of measles-induced immune amnesia on childhood infectious disease mortality

Article Title: Why historical data matter for understanding the long-term effects of measles

Article References: Bendel, H., & Matthes, K. L. (2026). Why historical data matter for understanding the long-term effects of measles. International Journal of Public Health, 71, Article 1610290. https://doi.org/10.3389/ijph.2026.1610290

Image Credits: AI Generated

DOI: 10.3389/ijph.2026.1610290

Keywords: measles, immune amnesia, historical demography, historical epidemiology, child mortality, vaccination, infectious disease, Copenhagen, non-specific vaccine effects, public health, pre-vaccine era, mortality data

The research team, led by Antonio Gondim and including Chidozie Chukwu, Folashade Agusto, and Joshua Ologbonyo, built their analysis around a cumulative case series constructed from annual measles surveillance records. Rather than modeling yearly incidence alone, they tracked the total number of cases accumulated over time, a measure that permanently retains the effects of major outbreaks. This approach allowed them to quantify how resurgences in 2014, 2019, and 2025 produced lasting upward shifts in national measles burden. The cumulative trajectory, because it increases monotonically and each annual value differs from the previous one by a comparatively small increment, forms a smooth curve that statistical models can track with high precision during stable periods.

Four forecasting frameworks were compared: a Poisson generalized linear model, a quasi-Poisson GLM, a negative binomial GLM, and an ARIMAX grid-search model. The count-regression models use a log-linear mean structure with a baseline time trend and cumulative outbreak-shift indicators for 2014, 2019, and 2025. These indicators capture the fact that once cases occur during an outbreak year, they remain part of the cumulative total in all later observations. The ARIMAX model, by contrast, combines a regression mean with an autoregressive error process, allowing recent annual activity to inform short-term predictions. The researchers selected the ARIMAX specification through an explicit grid search over candidate orders rather than automatic stepwise selection, ultimately choosing a model with two autoregressive terms.

The three count-regression models produced nearly identical parameter estimates and fitted trajectories. The estimated outbreak-shift coefficients were all positive and statistically significant, corresponding to multiplicative increases of approximately 1.1 percent for 2014, 1.8 percent for 2019, and 2.9 percent for 2025 on the cumulative baseline. The quasi-Poisson model estimated a dispersion parameter of roughly 0.11, indicating pronounced underdispersion relative to the Poisson variance assumption. This result is a structural consequence of modeling cumulative rather than incident counts: the smooth, monotonically increasing trajectory exhibits far less year-to-year variability than a Poisson distribution with a large cumulative mean would imply. The negative binomial dispersion parameter was effectively zero and statistically insignificant, causing that model to collapse toward the Poisson specification.

The ARIMAX grid-search model told a different statistical story. Its two autoregressive terms were both statistically significant, indicating residual temporal dependence after accounting for the time trend and outbreak pulse. However, the one-year outbreak pulse indicator, which retained only the 2014 and 2025 pulses, was not statistically significant and carried a very wide confidence interval. The researchers attribute this imprecision to parameter-identifiability limitations: with only two outbreak pulses in a short annual series, the pulse effect is partially absorbed by the autoregressive terms and the estimated trend. A separate 2019 pulse was not retained because adding it produced unstable coefficients and inflated standard errors due to collinearity with the autoregressive dynamics.

In-sample accuracy strongly favored the count-regression models. The Poisson and quasi-Poisson models achieved a training mean absolute error of 64.60 cumulative cases and a root mean squared error of 83.85, while the negative binomial model performed almost identically. The ARIMAX model, with training MAE of 341.24 and RMSE of 499.82, appeared substantially weaker on historical fit. But the held-out 2026 validation reversed this ranking entirely. The researchers withheld the first four months of 2026 data from model fitting and used the observed partial-year cumulative total as a direct validation target. As of May 1, 2026, the cumulative count stood at 84,565 cases.

Every model fell short of that observation. The Poisson, quasi-Poisson, and negative binomial models all forecast approximately 82,842 cumulative cases for 2026, underestimating the observed total by roughly 1,723 cases. The ARIMAX model, though closer, still underpredicted by approximately 1,416 cases. On the annual-increment scale, the gap was even starker: the count-regression models implied only about 91 additional cases for 2026, while 1,814 cases had already been reported by May 1. The ARIMAX model implied roughly 398 cases, still far below the observed burden. The researchers supplemented this single-point validation with rolling one-year-ahead validation over the 2016–2025 test period, refitting each model using only data available before each test year. The count-regression models achieved lower MAE values in this exercise, while the ARIMAX model achieved a lower RMSE, indicating better performance in reducing larger forecast errors.

The systematic underprediction across all four models carries a clear epidemiological conclusion: the 2026 outbreak cannot be explained as a continuation of the 2025 outbreak effect alone. The forecasted annual burden was effectively reached within the first four months of the year, implying that the final 2026 cumulative burden will substantially exceed that of previous years. The researchers note that non-outbreak years in the training window averaged approximately 111 annual cases, with a maximum of 381, while the three documented resurgences reached 667 cases in 2014, 1,274 in 2019, and 2,285 in 2025. The 1,814 cases already reported by May 1, 2026 exceed the largest ordinary year more than threefold.

Based on these findings, the team proposes a simple, model-agnostic surveillance rule: introduce a new outbreak-year indicator when the observed annual incident count exceeds approximately 500 cases, about four times the recent non-outbreak average, corroborated where possible by an external public-health signal such as a CDC outbreak declaration. Because this threshold is descriptive of annual increments rather than requiring estimation of a pulse coefficient, it sidesteps the identifiability limitations that plagued the ARIMAX outbreak indicator. The researchers caution that the threshold is calibrated on a small number of resurgence years and should be recalibrated as additional outbreak years accrue.

The study highlights a fundamental tradeoff between explanatory and predictive performance in infectious disease forecasting. Count-regression models provide superior historical fit and direct epidemiological interpretation, quantifying how major outbreak periods produce persistent shifts in cumulative burden. Time-series models sacrifice some interpretability but gain the ability to adapt to recent trends and improve short-term forecasts. The researchers suggest that future forecasting efforts should incorporate a dedicated 2026 outbreak indicator or model the 2025–2026 period as a separate outbreak phase, and that accuracy may be further improved by adding covariates such as vaccination coverage, vaccine exemption rates, population mobility, and vaccine hesitancy. As the 2026 resurgence continues to unfold, the findings underscore that public health tracking must adapt to a heightened risk environment that historical patterns alone can no longer anticipate.

Subject of Research: Insights on United States cumulative measles cases during the 2026 outbreak using ARIMA and generalized linear models

Article Title: Insights on United States cumulative measles cases during the 2026 outbreak using ARIMA and generalized linear models

Article References: Gondim, A., Chukwu, C. W., Agusto, F. B., & Ologbonyo, J. (2026). Insights on United States cumulative measles cases during the 2026 outbreak using ARIMA and generalized linear models. Frontiers in Epidemiology, 6, Article 1921780. https://doi.org/10.3389/fepid.2026.1921780

Image Credits: AI Generated

DOI: 10.3389/fepid.2026.1921780

Keywords: Insights, United, States, cumulative, measles, cases, during, outbreak, ARIMA, generalized, linear, models

The review, which synthesised peer-reviewed literature and authoritative institutional sources published between January 2000 and June 2026, draws a technically important distinction between two categories of disease. Directly climate-sensitive infections, including cholera, malaria, dengue, and Rift Valley fever, are influenced by climatic and environmental conditions through water, vector, and ecological pathways. Indirectly climate-amplified vaccine-preventable diseases, including measles, diphtheria, and polio, are driven primarily by displacement, malnutrition, overcrowding, and interrupted immunisation, all of which intensify when climate shocks strike. The authors stress that preserving this distinction matters because each category demands different surveillance triggers and different preparedness responses.

The cholera pathway illustrates the mechanics. Flooding can contaminate water sources and overwhelm sanitation systems, while drought pushes households and internally displaced person communities toward unsafe water points and erodes hygiene capacity. World Health Organization Regional Office for the Eastern Mediterranean situation reports have documented continued cholera and acute watery diarrhoea transmission following the 2023 outbreak wave, including spread into flood-affected districts, with inadequate safe water and sanitation among displaced populations identified as a major risk. In a climate-informed system, rainfall and flood alerts, WASH breakdown reports, displacement density, and diarrhoeal clusters would be monitored together so that water treatment, case management, and community response could be triggered earlier.

Vector-borne diseases require a different surveillance lens. Malaria risk in Somalia is mediated by seasonal rainfall, flooding, standing water, and temperature, which shape Anopheles mosquito breeding, particularly where displacement and disrupted access to prevention and treatment increase vulnerability. Dengue has been confirmed in Puntland and Banadir, and outbreak investigations have identified stagnant water, containers, and other household breeding sites as important local risks. The review notes that modelling from Ethiopia and broader African evidence suggesting climate change could shift disease burden from malaria toward arboviruses should be treated as contextual rather than Somalia-specific. For these diseases, the authors argue, surveillance should combine climate data, fever syndromic reporting, entomological monitoring, diagnostic readiness, and district risk mapping.

Rift Valley fever stands out as the country’s most significant zoonotic climate-sensitive threat. In Somalia’s 2023 zoonoses prioritisation exercise, RVF was ranked first among seven priority zoonoses, reflecting the country’s deep dependence on livestock. Serological evidence of the virus in ruminants from Afgoye and Jowhar indicates exposure at the animal interface, although the human burden remains poorly characterised. Because risk rises with heavy rainfall, flooding, livestock movement, and mosquito proliferation, the review argues that surveillance must connect animal abortion events, unexplained livestock mortality, vector signals, and human febrile alerts before human cases appear, a quintessentially One Health requirement spanning human, animal, and environmental sectors.

On the vaccine-preventable side, Somali studies show that vaccination uptake among internally displaced populations is shaped by household, service, and policy barriers, while zero-dose children are concentrated in nomadic, remote, and conflict-affected communities. Climate shocks amplify risk through displacement, malnutrition, overcrowding in settlements, cold-chain disruption, and reduced healthcare access. The corresponding warning signals are therefore not meteorological but social: internal displacement influxes, Integrated Food Security Phase Classification acute malnutrition classifications of Phase 3 or higher, low immunisation coverage, and the identification of zero-dose clusters. Preparedness actions include mobile vaccination outreach, zero-dose child mapping, cold-chain monitoring, and community health worker deployment.

Somalia is far from devoid of surveillance assets. The Early Warning Alert and Response Network, built incrementally since 2008, and the Integrated Disease Surveillance and Response System with its DHIS2 platform, operational since 2016, form the health surveillance core. A formal evaluation of EWARN from 2017 to 2020 documented meaningful progress: the proportion of timely reports rose from 24.6 percent in 2017 to 96.8 percent by 2020, and alert verification improved from 2.0 percent to 52.6 percent over the same period. Yet data completeness averaged below 60 percent across all four evaluation years, and the system remains insufficiently integrated with non-health warning platforms. Beyond the health sector, the Famine Early Warning Systems Network, the Food Security and Nutrition Analysis Unit, WASH cluster monitoring, displacement tracking, nutrition surveillance, and livestock reporting all generate relevant intelligence. An ecological study of displacement in Somalia found strong associations between failed rains and population movement at a three-month lag and food insecurity at a one-month lag, temporal patterns with direct implications for outbreak preparedness. None of these streams are routinely fused with disease surveillance at the district level or with each other.

The governance and financing barriers the review identifies are structural rather than technological. A global analysis of 64 infectious disease warning and response systems found that 80 percent were reactive, designed to respond after case counts rise, and only 6 percent were prevention-centred, linking upstream risk signals to strategies addressing the drivers of disease emergence. Somalia exemplifies this pattern. Disease surveillance, food security monitoring, WASH assessment, displacement tracking, livestock health reporting, and hydrometeorological forecasting each operate through separate mandates, funding lines, and reporting hierarchies. Somalia’s 2023 IHR-PVS National Bridging Workshop identified joint surveillance systems, high-level ministerial coordination, and emergency funding structures as priority unmet needs. At the district level, many health teams lack trained personnel, diagnostic equipment, reliable connectivity, and logistics for timely alert verification, while insecurity restricts access to conflict-affected areas and laboratory capacity remains concentrated in a small number of facilities.

Financing emerges as perhaps the most binding constraint. Somalia’s IDSRS implementation progress stands at only 15 percent for the financing domain, the lowest across all assessed dimensions, reflecting prolonged over-reliance on short-term, project-cycle humanitarian funding. This structure impedes sustained investment in surveillance staffing, supply pre-positioning, routine supervision, and the flexible pre-allocated budgets that anticipatory preparedness requires. One Health coordination, meanwhile, remains nascent and dependent on external donor support, not yet embedded in government planning or budgeting at federal, state, or district levels. These deficits fall hardest on the populations bearing the greatest risk: internally displaced persons, nomadic and agropastoral communities, malnourished children, zero-dose children, and people in insecure or hard-to-reach areas, all of whom are less visible in routine surveillance and less likely to be reached by early response.

The framework the authors propose does not require new institutions. It builds on existing assets and operates in five linked stages: multisource signal detection combining climate forecasts, WASH conditions, displacement movements, nutrition intelligence, livestock reports, laboratory information, and community signals; integrated district risk assessment that interprets these signals jointly with EWARN and IDSRS data; a disease-specific trigger decision against pre-agreed criteria; early preparedness action such as commodity pre-positioning, rapid-response team mobilisation, and targeted outreach; and feedback, accountability, and learning to refine triggers over time. An illustrative composite trigger for a flood-prone district along the Jubba or Shabelle rivers could activate when an official flood warning coincides with documented deterioration in safe water or sanitation and an increase in acute watery diarrhoea alerts, though the authors emphasise that exact thresholds would require local calibration and prospective validation. The deeper reframe is conceptual: climate-informed surveillance should be understood not as better data collection but as an anticipatory public health function designed to act before climate shocks converge with vulnerability and become infectious disease emergencies. The lessons, the authors argue, extend well beyond Somalia to any fragile, conflict-affected, and climate-vulnerable setting where warnings already exist but action does not follow.

Subject of Research: Climate-informed surveillance and early warning systems for climate-sensitive infectious diseases in Somalia

Article Title: Climate-informed surveillance for climate-sensitive infectious diseases in Somalia: early warning systems, policy gaps, and preparedness priorities

Article References: Hassan, A. A., Sudi, L. A., Mohamed, M. D., Ibrahim, I. O., & Abdullahi, Y. B. (2026). Climate-informed surveillance for climate-sensitive infectious diseases in Somalia: early warning systems, policy gaps, and preparedness priorities. Frontiers in Epidemiology, 6, Article 1907542. https://doi.org/10.3389/fepid.2026.1907542

Image Credits: AI Generated

DOI: 10.3389/fepid.2026.1907542

Keywords: Somalia, climate change, infectious disease surveillance, early warning systems, cholera, malaria, dengue, Rift Valley fever, measles, One Health, anticipatory action, fragile health systems

The historical arc matters for understanding why. After the 1991 civil war dismantled national health infrastructure, Somalia operated for years without any routine surveillance mechanism at all. The Early Warning Alert and Response Network, or EWARN, was established in 2008 as an emergency-oriented system and became the country’s sole multidisease surveillance mechanism for over a decade. It was deactivated amid conflict before being reactivated in 2017 during a severe drought and cholera emergency. EWARN proved effective at rapid alert generation during crises, but its provisional design was never intended to substitute for a permanent national surveillance architecture. Vertical, disease-specific systems for polio and malaria persisted alongside it, generating duplication and coordination gaps that complicated any coherent national picture of disease activity.

A pivotal shift followed Somalia’s 2016 Joint External Evaluation of International Health Regulations core capacities, which revealed limited or no capacity across nearly all surveillance indicators. That assessment prompted the 2020–2024 National Action Plan for Health Security, which prioritized integrated disease surveillance as the central strategy for closing the gaps. The COVID-19 pandemic then exposed the costs of fragmentation and catalyzed the establishment of incident management structures and emergency operations centers that later became foundational to the Integrated Disease Surveillance and Response system, or IDSR. Somalia formally established a functioning IDSR in 2021, guided by a costed three-year operational plan spanning governance, information technology, laboratory networks, and surveillance-response functions, with the District Health Information Software 2 tracker application selected as the national reporting platform.

The technical results of that transition are measurable. A 2024–2025 mixed-methods evaluation found that all federal member states had achieved functional electronic IDSR at the facility level and met the World Health Organization benchmark of at least 80 percent reporting timeliness and completeness, with the notable exception of the Banaadir region, where timeliness fell to 44 percent. The DHIS2 tracker customization has enabled standardized weekly aggregate reporting from hundreds of facilities and supports automated dashboards for epidemiological bulletin generation. However, the immediate case-based reporting component remains only partially deployed on health workers’ mobile devices, and manual transmission persists in many districts. Data generation, in other words, has outpaced data utilization.

The most striking quantitative indicator of that imbalance is alert verification. Only 46.5 percent of public health alerts reported through IDSR had been verified nationally, with substantial interstate variation ranging from 33 to 67 percent. Verification is the step that separates a raw signal from an actionable outbreak lead; without it, laboratory confirmation, epidemiological investigation, and timely response cannot follow. The 2024 IDSR evaluation explicitly identified poor laboratory capacity and weak linkage between surveillance data and laboratory confirmation as recurring implementation barriers across all federal member states. Specimen transport networks between peripheral facilities and regional reference laboratories remain limited, and diagnostic capacity beyond Mogadishu is thin, which delays confirmation of suspected events even when alerts are generated promptly.

Community-based and event-based surveillance, both essential complements to facility reporting for detecting signals from informal and hard-to-reach populations, remained non-operational nationally as of late 2024. This is a significant structural gap in a country where more than 2.6 million internally displaced persons live largely outside routine facility catchment areas, and where nomadic pastoralist communities move across vast territories. Evidence from Somaliland demonstrates what is feasible: a community-based surveillance program using trained community health volunteers and an SMS-based reporting platform generated 138 signals in a single year, with 83 percent verified and escalated to health authorities within 24 hours, triggering interventions such as oral rehydration distribution. Scaling that model nationally, the review argues, could close detection gaps that facility-based reporting alone cannot reach.

The disease burden driving these surveillance demands is itself compound. During the first months of 2024, more than 4,380 cholera cases and 54 deaths were reported across 32 districts, with a case fatality rate of 1.2 percent. Measles remains endemic, with routine immunization coverage estimated at approximately 20 percent, leaving substantial numbers of children susceptible. Between September 2021 and January 2023, officers trained through the Field Epidemiology Training Program investigated 54 measles outbreaks, of which 50 were confirmed, alongside 17 cholera outbreaks. Polio transmission, including circulating vaccine-derived poliovirus, has persisted despite repeated vaccination activities. Tuberculosis remains a major burden, with WHO estimating approximately 43,000 incident cases and 11,000 deaths in a recent reporting year. Malaria and other vector-borne diseases are shifting with changing rainfall and temperature patterns, and Somalia’s extensive human-livestock interaction creates zoonotic risks that a predominantly human-health surveillance system does not adequately capture.

Beneath these technical gaps lie structural constraints that reinforce one another. Governance fragmentation distributes outbreak authority across six federal member states and numerous partners, producing duplicated assessments, delayed release of essential commodities, and inconsistent application of technical guidelines across jurisdictions. Financing is perhaps the most binding constraint: international donors cover roughly half of national health expenditure, and IDSR implementation surveys identified financing as the weakest thematic area, scoring only 15 percent progress against WHO benchmarks. Human resources scored 16 percent in the same assessment, reflecting a health worker density of fewer than 0.4 doctors, nurses, and midwives per 10,000 population against a WHO minimum threshold of 23 per 10,000. Security instability and humanitarian access constraints intersect with all of these deficits, interrupting supportive supervision, disrupting cold-chain logistics, and creating persistent blind spots precisely where outbreak risk is highest.

The review is nonetheless careful to distinguish between what Somalia lacks and what it has demonstrated it can do. Large-scale vaccination campaigns reaching more than 1.7 million children for polio and 1.5 million for measles show that substantial operational capacity can be mobilized when resources, coordination, and implementation align. The Field Epidemiology Training Program has graduated six cohorts by early 2025, with trainees investigating 95 outbreaks between September 2021 and January 2023, though only 51 percent were investigated within 48 to 72 hours of alert. Ten graduates from the first cohort became co-mentors, building national mentoring capacity, and the sixth cohort focused specifically on immunization service delivery and laboratory system strengthening. The challenge, the authors conclude, is not the absence of response capacity but its continuity and integration with routine surveillance and prevention systems.

The strategic prescription that emerges is one of sequencing rather than simultaneous transformation. In the short term, the priorities are consolidating existing IDSR gains: raising alert verification rates beyond the current 46.5 percent national average, closing the timeliness gap in underperforming states, and completing nationwide deployment of mobile case-based reporting. Medium-term priorities include scaling the Field Epidemiology Training Program toward intermediate and advanced tiers, institutionalizing community-based and event-based surveillance nationally, and revitalizing multisectoral technical working groups that have shown declining engagement. Long-term priorities require transitioning toward predictive surveillance that integrates climate, laboratory, and epidemiological data streams to anticipate outbreaks before case counts rise, alongside securing sustainable domestic financing. Digital technologies, the review insists, should be treated as enabling tools within a mature surveillance architecture rather than substitutes for the core capacities of verification, laboratory confirmation, and investigation. Somalia’s next phase of health-security development, the authors suggest, should be judged not by how much data the system generates but by how effectively that information leads to timely action and reduced outbreak risk.

Subject of Research: Infectious disease surveillance and outbreak preparedness in Somalia

Article Title: From detection to response: a critical narrative review of infectious disease surveillance and outbreak preparedness in Somalia

Article References: Abdi, M. S., Abdi, Y. H., & Bashir, S. G. (2026). From detection to response: a critical narrative review of infectious disease surveillance and outbreak preparedness in Somalia. Frontiers in Tropical Diseases, 7, Article 1951505. https://doi.org/10.3389/fitd.2026.1951505

Image Credits: AI Generated

DOI: 10.3389/fitd.2026.1951505

Keywords: Somalia, disease surveillance, outbreak preparedness, Integrated Disease Surveillance and Response, International Health Regulations, cholera, measles, polio, One Health, Field Epidemiology Training Program, health security, fragile states

The research, led by Sheikh Abdulhafed Al-Shoteri of the University of Aden and the Yemen National Public Health Institute together with colleagues from Princeton University and Yemeni institutions, offers one of the most detailed portraits yet of how a time-limited catch-up campaign performs inside a fragile and conflict-affected setting. The team triangulated five data streams collected in southern Yemen in 2025: administrative immunization records, forty key informant interviews with program managers and health officials, twelve focus group discussions with caregivers and community members, a survey of 242 vaccinators, and direct observation of forty vaccination sessions. Quantitative data were analyzed descriptively while qualitative material was examined thematically, allowing the researchers to cross-check what program documents claimed against what health workers and families actually experienced on the ground.

The technical picture that emerges is one of systemic breakdown rather than isolated failure. Yemen’s routine immunization infrastructure has been decimated by years of war, producing a large cohort of zero-dose children and fueling recurrent outbreaks of measles, diphtheria, pertussis and polio, including circulating vaccine-derived poliovirus type 2. The COVID-19 pandemic then widened already severe coverage gaps by disrupting service delivery and diverting scarce resources. When the Big Catch-Up finally launched in southern Yemen in September 2024, it did so amid these pre-existing system-level failures. Updated tools and standard operating procedures, the study found, arrived only months after vaccination activities had already begun, leaving frontline teams to improvise without current guidance during the campaign’s most critical early phase.

Microplanning, the granular process by which health authorities map target populations and allocate vaccinators to specific communities, was built on a national census dating from 2004. Two decades of mass displacement had rendered those population estimates profoundly inaccurate, meaning planners were chasing targets anchored to a demographic landscape that no longer existed. In a country where millions of people have been internally displaced, families move repeatedly across governorate lines, and entire villages may be abandoned or newly settled, a census-based denominator systematically miscounts the very children the campaign was designed to find. The consequence was a planning architecture that could not reliably identify where zero-dose children lived, how many there were, or how to reach them.

Human resource constraints compounded the problem. Training for vaccinators was brief, and field supervision was consistently weak across the districts studied, according to the vaccinator survey and observed sessions. At the same time, concurrent outbreak response operations for measles and polio pulled the same limited workforce away from catch-up activities, forcing an impossible competition for staff, vehicles, cold-chain capacity and attention. Demand-generation activities, the community outreach and communication work that persuades hesitant families to bring children forward, were chronically underfunded. The study found insufficient attention to social and behavior change programming, which created additional barriers to uptake precisely where vaccine confidence was already fragile.

Caregivers and community members interviewed for the study described a web of practical and social obstacles, particularly for older children aged 24 to 59 months, who were reached at consistently lower rates than younger infants across all antigens and geographies. Distance to vaccination sites and the cost of transport weighed heavily in a country where fuel prices and road insecurity make travel expensive. Restrictions on some women’s mobility, tied to customs requiring a male escort known as a mahram, limited the ability of mothers to bring children to health facilities without a male relative available to accompany them. Rumors and fear of adverse events following immunization circulated in communities, and with underfunded communication channels there was little structured effort to counter misinformation before it took root.

The administrative reach data reveal striking variation by vaccine type, dose and geography. Reach for the third dose of pentavalent vaccine, at 3.7 percent nationally against antigen-specific targets, was less than half the figure for the first dose, a pattern consistent with the well-documented difficulty of completing multi-dose schedules in settings where families must return repeatedly to fixed sites. The consistently lower performance among children aged 24 to 59 months is epidemiologically significant because this older cohort carries much of the accumulated susceptibility driving Yemen’s measles and pertussis outbreaks. Children who missed their primary series as infants remain susceptible through early childhood, and campaigns that successfully reach infants but fail to mobilize older children leave the outbreak reservoir largely intact.

The authors’ central conclusion is sobering for global health policy: external financing and high-level policy commitment, however generous, may be insufficient to deliver equitable catch-up vaccination when implementation depends on a fragile, conflict-affected health system. The same weaknesses that have long undermined routine immunization in Yemen, from broken supply chains and absent supervision to inaccurate population data and eroded community trust, also govern the fate of emergency campaigns layered on top of them. A time-bound initiative parachuted into this environment inherits its constraints rather than escaping them. The study suggests that catch-up campaigns cannot substitute for sustained investment in primary health care, meaningful community engagement, improved population estimates and financing models that extend beyond short donor project cycles.

The findings carry implications well beyond Yemen. Fragile and conflict-affected settings now account for a growing share of the world’s zero-dose children, and the global immunization community has increasingly turned to campaign-style approaches to close pandemic-era gaps. The Yemen case demonstrates that in such settings the binding constraint is rarely vaccine supply or global funding alone; it is the operational capacity of the health system itself, including its ability to plan against real populations, supervise and support its frontline workers, communicate credibly with communities and maintain services between campaigns. Where those capacities are absent, administrative targets may be missed by an order of magnitude, and the children at greatest risk, the oldest, the most displaced and the most isolated, are systematically the last reached.

For Yemen’s Ministry of Public Health and Population and its international partners, the study points toward concrete priorities: updating population denominators to reflect displacement realities, front-loading guidance and training before activities begin, protecting immunization staff from competing outbreak demands, and funding sustained social and behavior change work rather than treating communication as an afterthought. More fundamentally, the authors argue, the international community must recognize that recovering pandemic-era immunization losses in fragile states is not a campaign problem but a health system problem, one that requires financing horizons measured in years rather than project cycles. Until the underlying architecture of primary care is rebuilt, catch-up initiatives in Yemen and similar settings will continue to measure not what the world hopes to achieve for forgotten children, but how little a broken system can deliver.

Subject of Research: Implementation of the Big Catch-Up vaccination initiative in conflict-affected Yemen and the role of fragile routine immunization systems

Article Title: Catching up in crisis: implementation of the big Catch-Up initiative in Yemen within a context of fragile routine immunization systems

Article References: Al-Shoteri, S. A., Sharkey, A., Ghouth, A. S. B., Ba-Saddik, I. A. M., AlNoban, M. S., Alwaleedi, A. A., Saleh, S. A., & Akil, N. R. H. (2026). Catching up in crisis: implementation of the big Catch-Up initiative in Yemen within a context of fragile routine immunization systems. International Journal for Equity in Health. https://doi.org/10.1186/s12939-026-03029-0

Image Credits: AI Generated

DOI: 10.1186/s12939-026-03029-0

Keywords: Big Catch-Up, Yemen, zero-dose children, routine immunization, fragile and conflict-affected settings, vaccination coverage, health systems strengthening, measles, pentavalent vaccine, immunization equity, COVID-19, primary health care

The core of the concern raised by APIC and SHEA is operational rather than abstract. Infection preventionists and healthcare epidemiologists working on the front lines of American medicine depend daily on the CDC’s science, surveillance systems, and guidance documents to make decisions that protect both patients and healthcare personnel. When a hospital investigates a cluster of healthcare-associated infections, when a nursing home must respond to an outbreak of a respiratory pathogen, or when an outpatient clinic needs to update its vaccination protocols, the technical foundation for those decisions typically originates at the federal agency. According to the joint statement, that foundation is visibly weakening: guidance is slower to arrive, technical assistance is harder to reach, and scientific expertise is thinner precisely when it is most needed.

The timing of the reported workforce losses amplifies the risk. Healthcare facilities are entering the respiratory virus season without updated federal vaccine recommendations, a gap that leaves infection prevention teams without the authoritative national benchmarks they have historically relied upon to standardize immunization practices across institutions. At the same time, facilities are preparing for potential measles exposures, a disease that demands rapid identification, isolation, and contact tracing protocols grounded in current epidemiological evidence. The organizations also point to the monitoring of imported threats such as Ebola, which requires sustained laboratory capacity, surveillance infrastructure, and rapid communication channels between federal scientists and local practitioners. Each of these scenarios depends on a functioning national public health partner, and each becomes more hazardous when that partner is operating with a substantially reduced workforce.

Infection prevention is a discipline built on the rapid translation of scientific evidence into bedside practice. Infection preventionists are the specialists who design and enforce the protocols that prevent healthcare-associated infections, which affect millions of patients worldwide each year and represent one of the most common adverse events in medical care. Healthcare epidemiologists complement this work by applying epidemiological methods to detect outbreaks, evaluate antimicrobial resistance patterns, and assess the effectiveness of preventive interventions within healthcare settings. Both professions operate within a distributed network in which local expertise is amplified by national coordination. The CDC functions as the hub of that network, synthesizing data from thousands of facilities, issuing evidence-based recommendations, and providing the laboratory and technical infrastructure that individual institutions cannot replicate on their own.

APIC President Kathy Ward, a registered nurse with advanced credentials in infection control, framed the relationship between frontline practitioners and the federal agency as a partnership that is now under strain. In the statement, she emphasized that infection preventionists safeguard the nation’s healthcare system against healthcare-associated infections and that the profession depends on the CDC to provide timely, evidence-based guidance. She warned that the losses described in the reporting put that partnership, and patient safety itself, at risk. Her comments reflect a practical reality: when federal guidance is delayed or unavailable, individual facilities must improvise, and improvisation in infection control can lead to inconsistent practices, gaps in protection, and ultimately preventable infections.

SHEA President Lisa Maragakis, a physician and epidemiologist, directed her warning toward a longer-term consequence of workforce erosion. In the statement, she observed that healthcare epidemiology is built on sound science and trusted data, and she characterized the CDC’s scientific independence and expert workforce as national assets that cannot be rebuilt overnight once they are lost. This point carries particular technical weight. The scientists who staff the agency’s emerging infectious disease and respiratory disease centers accumulate institutional knowledge, methodological expertise, and operational experience that are not easily transferred or replaced. Experienced federal scientists develop the capacity to recognize early signals of emerging threats, to design surveillance systems that capture meaningful data, and to communicate complex findings to practitioners who need actionable guidance. When such experts depart, their institutional memory departs with them, and rebuilding that capacity requires years of recruitment, training, and mentorship.

The downstream effects of a weakened CDC do not remain contained within the agency. As APIC and SHEA describe it, when the national partner is weakened, the burden shifts to already stretched healthcare facilities and to state and local health departments, many of which have faced their own staffing and funding challenges in recent years. State and local public health agencies depend on federal technical assistance, laboratory confirmation capabilities, and coordinated data systems to carry out their mandates. When federal capacity contracts, these agencies absorb responsibilities they may lack the resources to fulfill, and the resulting gaps propagate outward to patients and communities, who ultimately bear the consequences in the form of increased exposure to preventable infections and slower responses to outbreaks.

In response to the situation, the two organizations have issued a three-part call to action directed at Congress and the Administration. First, they urge the restoration and sustained support of CDC staffing in infectious disease programs, healthcare quality promotion, and laboratory operations, the specific divisions whose expertise underpins infection prevention practice nationwide. Second, they call for the protection of the agency’s scientific independence, reflecting a concern that political interference in scientific processes would further undermine the credibility and reliability of federal guidance. Third, they demand that funds appropriated for state and local public health partners be distributed promptly, ensuring that the frontline agencies responsible for local outbreak response receive the resources that Congress has already allocated. Together, these recommendations address the workforce, the institutional safeguards, and the funding pipelines that the organizations view as the essential infrastructure of national infection prevention capability.

The statement also situates the current moment within a broader understanding of how healthcare safety is produced. The prevention of healthcare-associated infections is not achieved by any single institution acting alone; it is the product of a layered system in which federal science, state and local public health infrastructure, and frontline clinical expertise reinforce one another. Surveillance data collected by the CDC inform the guidelines that infection preventionists implement in their facilities, and the observations of those frontline practitioners in turn feed back into national evidence. Disruption at any layer degrades the entire system, but disruption at the federal layer is particularly consequential because it affects every facility simultaneously. The organizations’ warning suggests that the reported loss of nearly a third of the agency’s workforce represents precisely such a systemic disruption, one whose effects are already observable in delayed guidance and reduced access to technical assistance.

As respiratory virus season proceeds and as facilities continue to prepare for measles exposures and monitor imported threats, the concerns articulated by APIC and SHEA are likely to frame an ongoing policy debate about the nation’s public health readiness. The organizations’ message is that the expertise housed within the CDC constitutes a form of national infrastructure comparable in importance to physical systems, and that its loss carries consequences measured not in budget figures but in patient outcomes. Their statement serves as both a diagnosis of the current strain on the infection prevention community and a formal request to federal policymakers to restore the scientific capacity on which American healthcare safety has long depended. Whether that request translates into legislative and administrative action remains to be seen, but the two societies have made clear that, in their assessment, the window for protecting this critical national asset is narrowing.

Subject of Research: Impact of CDC workforce reductions on infection prevention and healthcare epidemiology

Article Title: APIC and SHEA Statement on reported erosion of CDC capacity

Article References: APIC and SHEA Statement on reported erosion of CDC capacity. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: CDC, APIC, SHEA, infection prevention, healthcare epidemiology, public health workforce, healthcare-associated infections, respiratory virus season, vaccine recommendations, measles, Ebola, health policy

The urgency of the modeling work is rooted in the epidemiological reality already unfolding across the nation. Measles is one of the most contagious human pathogens known, and the numbers reflect that extraordinary transmissibility. Co-author Abba Gumel pointed to a striking 650 percent increase in cases between 2024 and 2025, a surge that has accompanied steadily declining vaccine coverage. So far this year, 3,471 measles cases have been confirmed nationally, spreading across 45 states as well as Washington, D.C., and New York City. Recent clusters in Texas, New Mexico and South Carolina emerged as those states slipped below their respective vaccine-induced herd immunity thresholds, the minimum proportion of a population that must be immune to interrupt sustained person-to-person transmission of the virus.

To assess what might happen if Florida repeals its school-entry requirement, the Maryland team constructed a transmission model calibrated on the 2025 measles outbreak in Gaines County, Texas, one of the most significant recent U.S. outbreaks. The researchers then layered in Florida-specific demographic structure, real MMR vaccination coverage data, and realistic mixing patterns across age groups and geographic areas. This approach allowed the model to capture how measles would actually move through Florida’s population rather than relying on simplified assumptions of uniform contact. The result is a computational framework capable of projecting outbreak scale, trajectory and severity under different policy and vaccination-coverage scenarios.

The model’s baseline finding is sobering even before any policy change is considered. According to the simulations, Florida’s vaccine-induced herd immunity threshold is already below the level needed to protect the state against sustained measles transmission, meaning the population’s collective immunity has eroded to a precarious point. When the researchers then simulated declines in MMR vaccination coverage following the removal of school-entry requirements, the potential for large outbreaks increased further, with projected pediatric deaths reaching numbers not seen since the pre-vaccine era. In other words, the state is not starting from a position of safety; the proposed repeal would push an already vulnerable system past a critical threshold.

One of the study’s most technically significant insights concerns the unequal impact of vaccinating different age groups. Oveson reported that vaccinating one child is three times more effective at reducing transmission than vaccinating one adult, a difference that stems primarily from how age groups interact. Children spend considerably more time in face-to-face contact than adults, whether in classrooms, playgrounds or other shared settings, and this contact structure makes them disproportionately important nodes in the transmission network. The practical consequence, she emphasized, is that small reductions in childhood vaccination rates can produce disproportionately large increases in the scale of outbreaks, a nonlinear relationship that policymakers may underestimate when weighing the perceived costs of mandates against their epidemiological benefits.

Oveson likened the current situation to wildfire risk, describing it as having a very dry forest with a lot of kindling. A large unvaccinated population that includes children, she explained, is the perfect setup to spark a very big and potentially deadly outbreak. The analogy captures a key feature of measles epidemiology: the virus’s basic reproduction number, among the highest of any human pathogen, means that even modest pockets of susceptibility can sustain explosive chains of transmission once the virus is introduced. In a population where immunity is unevenly distributed, those pockets can connect through schools and households, converting isolated introductions into widespread epidemics.

Gumel placed the findings in a longer historical context, noting that school-entry vaccination mandates for various infectious diseases have long been a cornerstone of U.S. public health policy and have proven to be an effective tool for preventing both disease spread and disease-related mortality. What is most troubling, he said, is that these mandates are known to effectively prevent the erosion of herd immunity. He also identified complementary measures: strengthening adult immunity through catch-up vaccination could help reduce the severity of outbreaks, and as-needed behavioral interventions such as masking and isolation could slow transmission. Crucially, however, he stressed that neither of these approaches can compensate for declines in childhood MMR coverage, underscoring the unique protective role that school-entry requirements play.

Florida’s policy environment adds further concern. The state has resisted behavioral measures in the past and already offers exemptions for individuals who decline vaccination for religious, personal or medical reasons. Vaccine exemption requests in Florida currently stand at 5.9 percent, well above the national average of 4.2 percent. Oveson argued that eliminating the school mandate would go a step further by signaling that vaccination is unnecessary, a message she described as inaccurate and dangerous. The new paper, she noted, provides quantitative evidence that such a policy change could make measles endemic in Florida, meaning the virus would circulate continuously within the state rather than appearing only in sporadic imported outbreaks, and could potentially reignite transmission across the entire United States.

Behind the numbers lies a shifting landscape of public attitudes. Recent national survey data show that approximately 16 percent of parents are not confident that the MMR vaccine is safe for children, 17 percent believe the risks of the MMR vaccine outweigh its benefits, and 18 percent fully oppose school-entry MMR vaccination mandates. Oveson argued that health officials would benefit from a better understanding of how people make vaccination decisions, particularly parents deciding on behalf of their children. Gumel agreed, emphasizing that targeted outreach is critical. Public health officials, he said, need to find ways to reach these parents if they are to prevent or contain future measles outbreaks wherever they occur, and he added that such outbreaks will occur, because the disease is out there, vaccination coverage is down, children are returning to school, and the data and science do not lie.

The study arrives at a moment when the scientific community is watching the erosion of one of public health’s greatest achievements. Measles elimination in the United States, declared decades ago after the widespread adoption of the MMR vaccine, depended on maintaining high and sustained childhood immunization coverage, and the Maryland model demonstrates how quickly that foundation can weaken when policy signals change. By quantifying the projected effects of removing school-entry vaccination requirements, the researchers have converted an abstract policy debate into concrete epidemiological terms: outbreak scale, transmission persistence and preventable pediatric deaths. Whether Florida’s lawmakers heed these projections or proceed with repeal, the study offers a rigorous, data-driven preview of the consequences, and a reminder that in the mathematics of infectious disease, small changes in vaccination behavior can cascade into outcomes of historic magnitude.

Subject of Research: Mathematical modeling of measles transmission in Florida under proposed repeal of school-entry MMR vaccination requirements

Article Title: Study foresees heightened measles epidemic risk for Florida

Article References: Study foresees heightened measles epidemic risk for Florida. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: measles, MMR vaccine, Florida, herd immunity, vaccination mandate, epidemiological modeling, vaccine hesitancy, public health policy, outbreak projection, school-entry requirements, transmission dynamics, University of Maryland

The study drew on 289 children enrolled in the PROGRESS cohort in Mexico, a long-running birth cohort designed to examine how environmental exposures shape child health. Rather than relying on blood or urine samples, which capture only recent exposure, the researchers turned to deciduous teeth, the baby teeth that children naturally shed. Teeth grow in layers much like tree rings, and the dentine that forms during specific developmental periods locks in a chemical record of what circulated in the child’s bloodstream at the time. By segmenting dentine along growth lines, the team was able to retrospectively quantify arsenic exposure for every week from sixteen weeks before birth through fourteen weeks after birth, an unprecedented temporal resolution for an immunotoxicology study.

When the children returned for a follow-up visit around age four to five, the investigators measured serum levels of immunoglobulin G antibodies directed against six vaccine antigens: measles, mumps, and rubella from the MMR vaccine, and diphtheria, tetanus, and pertussis from the DTP series. These antibodies are the immune system’s memory of vaccination, the molecular shield that prevents re-infection, and their concentrations in blood are a standard benchmark of how well a vaccine has taken hold. The measurements were performed using a multiplexed Luminex bead-based immunoassay, a technique that allows all six antibody targets to be quantified simultaneously from a small serum sample.

The statistical challenge was considerable. Because arsenic exposure was estimated for thirty consecutive weeks, the researchers needed a method that could detect when in that timeline exposure mattered, not just whether it mattered overall. They employed Distributed Lag Non-linear Models, or DLNMs, a framework originally developed in environmental epidemiology for studying delayed and time-varying effects of air pollution and temperature. The models related log2-transformed dentine arsenic concentrations to log2-transformed antibody levels across every week of the perinatal period, while adjusting for the child’s age, maternal education, parity, and child sex. The log2 transformation means the reported effects can be read as the change in antibody level associated with a doubling of arsenic exposure during a given week.

The results converged on a single, well-defined period. A doubling of arsenic exposure in the window spanning one week before birth to six weeks after birth was associated with significantly lower anti-measles antibody levels, with an estimated effect of minus 5.62 on the log2 scale and a 95 percent confidence interval running from minus 8.39 to minus 0.83. The same perinatal window showed a significant association for anti-rubella antibodies, with an effect estimate of minus 3.85 and a confidence interval from minus 6.99 to minus 0.63. In practical terms, children with higher arsenic exposure in the weeks surrounding delivery carried measurably weaker antibody defenses against measles and rubella years later, even though their vaccinations occurred long after the exposure itself.

Just as telling was what the analysis did not find. Arsenic exposure during the perinatal window showed no significant association with antibody levels against mumps, diphtheria, tetanus, or pertussis. Nor did earlier or later periods of prenatal and early postnatal exposure produce significant signals for any antigen. This selectivity is biologically intriguing. It suggests that the immune pathways supporting long-term antibody maintenance against measles and rubella may be more sensitive to arsenic’s interference than those supporting the other four antigens, or that different vaccine antigens rely on differently timed developmental programs of B-cell and plasma-cell maturation that vary in their vulnerability to toxic insult.

The timing of the susceptible window makes biological sense. The weeks surrounding birth are a period of profound immunological transition. The fetus must shift from the sterile, maternally protected environment of the womb to an microbe-rich world, and neonatal immune cells are actively learning to distinguish threat from tolerance. Maternal antibodies transferred across the placenta are waning while the infant’s own antibody production is just beginning. Arsenic is known to disrupt immune signaling, generate oxidative stress, and interfere with methylation processes that regulate gene expression, and a toxic exposure during this delicate choreography could plausibly leave a lasting imprint on how well vaccine memory is established and maintained.

The researchers also probed whether the effects differed between boys and girls, or between children who were breastfed at one month postpartum and those who were not, since both factors can shape immune development and arsenic dynamics. They found no heterogeneity by either sex or breastfeeding status, indicating that the association between perinatal arsenic and reduced measles and rubella antibodies appears to operate similarly across these subgroups. That consistency strengthens the case that the finding reflects a general biological vulnerability rather than an effect confined to a particular subset of children.

The methodological innovation deserves particular attention. Traditional exposure assessment in environmental health has long been hampered by the difficulty of reconstructing what a person was exposed to years or decades earlier. Baby teeth offer a solution that is both retrospective and precise, and their use here demonstrates how naturally shed biomaterials can transform the study of developmental toxicology. Combined with the DLNM framework, which treats exposure timing as a variable to be mapped rather than averaged, the approach allowed the team to draw a temporal map of vulnerability with weekly resolution, something conventional single-biomarker studies simply cannot achieve.

The public health implications are significant. Measles remains one of the most contagious human pathogens, and even modest reductions in population-level antibody levels can erode herd immunity and fuel outbreaks, a concern made vivid by recent resurgences of measles in countries where the disease was once controlled. Arsenic contamination of groundwater affects an estimated hundreds of millions of people worldwide, and in regions such as Mexico, where the PROGRESS cohort is based, exposure often begins before birth. If the findings are confirmed in other cohorts, they would add vaccine-preventable disease susceptibility to the long list of harms attributable to early-life arsenic exposure, and they would sharpen the argument for reducing arsenic exposure among pregnant women and newborns, whether through water filtration, dietary interventions, or regulatory limits on contaminated sources. The study, funded by the National Institutes of Health and led by researchers at the Icahn School of Medicine at Mount Sinai together with collaborators at Mexico’s National Institute of Public Health and other institutions, was published open access, with the authors reporting no competing interests.

Subject of Research: Perinatal arsenic exposure and vaccine-specific antibody levels in children

Article Title: Susceptible perinatal windows to arsenic exposure and serum antibody levels in children

Article References: Scotti, A., India-Aldana, S., Martinez, M., Arora, M., McRae, N., Lamadrid-Figueroa, H., Quataert, S. A., Estrada-Gutierrez, G., Torres-Olascoaga, L., Téllez-Rojo, M. M., Wright, R. O., Jusko, T. A., & Colicino, E. (2026). Susceptible perinatal windows to arsenic exposure and serum antibody levels in children. Environmental Health. https://doi.org/10.1186/s12940-026-01331-6

Image Credits: AI Generated

DOI: 10.1186/s12940-026-01331-6

Keywords: arsenic exposure, perinatal window, vaccine antibodies, measles, rubella, immunotoxicology, baby teeth, dentine, PROGRESS cohort, DLNM, humoral immunity, environmental health

Verification of measles elimination is a retrospective judgment. It requires documented evidence of high vaccination coverage and of the interruption of endemic transmission for at least twelve consecutive months, confirmed through epidemiological, laboratory and molecular data reviewed by the commission. As such, it is an accurate statement about what has already happened in a country. It says nothing, however, about how much viral exposure a country is currently absorbing from the outside world. For most of the past two decades, that distinction was largely immaterial, because verified countries were surrounded by other verified countries and the regional firewall held. The loss of regional verification has now made the difference consequential, and a rapidly evolving situation in Brazil illustrates exactly why.

Between January and early August 2026, the state of São Paulo confirmed 23 measles cases, compared with just two in the whole of 2025. The cases clustered in the state capital, Guarulhos and São Bernardo do Campo, along the corridor served by the largest international air hub in South America. The first two cases, which occurred in March and April, were imported and affected unvaccinated individuals; the remainder were classified as import-related, with the source of infection unidentified at the time of writing. The response, it must be stressed, has been prompt and competent. A supplementary infant dose was recommended in the affected municipalities in June 2026, before the transmission chain was formally recognized. Brazil had been reverificated as measles-free in November 2024, five years after losing that status, having sustained interruption of endemic transmission since June 2022. Yet a capable programme, holding verified status, nonetheless found itself confronting a chain of transmission whose origin it could not trace.

The letter argues that two quantities, neither of which is captured by the current verification framework, would add prospective information at low cost. The first is importation pressure: a measure of how much measles virus is being introduced into a population by international travel. The concept builds on prior modeling work showing that an inflow variable, defined as the sum across origin countries of air passenger volume multiplied by measles incidence in the origin country, predicted imported measles cases in United States states with a correlation of 0.84 and an area under the receiver operating characteristic curve of 0.78. Crucially, that study found that both air travel data and international surveillance data contributed to the predictive performance, meaning that the signal emerges from the combination of connectivity and epidemiology rather than from either alone.

The proposed refinement is a modest extension and, more importantly, a change of use. Rather than confining the metric to predictive studies, the author suggests weighting the inflow by the susceptible fraction of the destination population and reporting the resulting quantity routinely alongside elimination status. For operational specification, the letter proposes a rolling three-month window; counting arriving passengers rather than scheduled flights, since seat capacity and passenger load differ substantially between routes; using incidence per million rather than absolute case counts, so that origin countries of different sizes are comparable; estimating susceptibility from two-dose rather than first-dose coverage; and stratifying by age band where subnational coverage data permit, since susceptibility is not uniformly distributed across age groups. A verified country could then state not only that endemic transmission has been absent, but how much introduction pressure it is presently absorbing.

The second proposed indicator is surveillance traceability, operationalized as the proportion of confirmed cases for which no epidemiological link to a known source can be established. This figure is already generated by routine case investigation in every elimination setting, but it is typically reported as a descriptive detail rather than monitored as an indicator in its own right. A case without an identifiable source may indicate unrecognised transmission occurring upstream, although it may equally reflect incomplete interview data, unrecognised exposure to a known case, population mobility, or insufficiently discriminatory viral sequencing. The letter is careful to frame the measure narrowly: it is an indicator of investigation and linkage capacity rather than a direct measurement of surveillance sensitivity. Its practical merit is availability. It can be computed continuously from data already collected, whereas the conventional criterion, the absence of endemic transmission over twelve months, resolves only in retrospect.

Considered jointly, the two quantities describe four distinct epidemiological situations. Low importation pressure combined with high traceability corresponds to a stable elimination setting, the condition most verified countries aspired to for years. High pressure with high traceability describes a heavily exposed system that is nonetheless tracking introductions successfully, the condition under which imported cases are contained without secondary spread. Low pressure with low traceability corresponds to a system whose investigative weakness is masked by the absence of challenge, a hidden fragility that would only become apparent once the virus arrived. High pressure with low traceability corresponds to a state of increased vulnerability to sustained transmission. The São Paulo metropolitan region in mid-2026, the letter argues, illustrates precisely this last category, and its defining features were in principle recognizable prospectively, from connectivity and linkage data, rather than only in hindsight from the case count.

The value of this framing, the author contends, is that it renders elimination continuous and prospective rather than binary and retrospective. Under current practice, supplementary campaigns, supplementary infant doses and reinforcement of laboratory capacity are triggered by confirmed cases. Indicators of exposure and traceability would allow such interventions to be triggered by exposure itself, potentially earlier, before sustained transmission becomes established. In an era when a single untraced importation in a susceptible pocket can reignite endemic transmission across an entire region, that shift in timing could prove decisive.

The letter is explicit that this is a proposal rather than a validated instrument, and the limitations are substantial. Neither quantity has been calibrated against real-world outcomes. The unlinked-case proportion is sensitive to investigation capacity and unstable at small case numbers, which is precisely the situation in most elimination settings where cases are rare. Importation pressure estimated from aggregate air connectivity ignores heterogeneity in traveller susceptibility and omits land and maritime movement, a limitation acknowledged within the air travel literature itself and one that is material in several countries of the region, including Brazil, which shares extensive overland borders. The case figures cited derive from official state communications rather than from a published epidemiological bulletin, and the outbreak was still ongoing at the data cut-off of 9 August 2026. The claim, therefore, is deliberately narrower than a method: that the status a country holds and the exposure it faces have become distinguishable quantities; that the distinction is measurable from data already being collected; and that measuring it is a more useful response to regional resurgence than enumerating cases once they appear. As the Americas work toward regaining regional verification, the letter suggests that sustaining elimination will require not just counting what has happened, but continuously measuring what is coming.

Subject of Research: Proposed indicators of measles importation pressure and surveillance traceability for sustaining elimination in the Americas

Article Title: Importation pressure and surveillance traceability: complementary indicators for sustaining measles elimination in the Americas

Article References: Faico-Filho, K. S. (2026). Importation pressure and surveillance traceability: complementary indicators for sustaining measles elimination in the Americas. New Microbes and New Infections, 73, Article 101842. https://doi.org/10.1016/j.nmni.2026.101842

Image Credits: AI Generated

DOI: 10.1016/j.nmni.2026.101842

Keywords: measles, elimination, Americas, importation pressure, surveillance, São Paulo, Brazil, air travel, PAHO, vaccination coverage, public health, epidemiology

The scientific case for immunisation has never been stronger. Modelling of fifty years of the Expanded Programme on Immunization shows that vaccines have made a major contribution to improved survival and health worldwide. Recent evaluations of meningococcal B vaccines demonstrate how careful development, rigorous surveillance and real-world data can produce highly effective and safe products that substantially reduce severe childhood disease. Human papillomavirus vaccination has been associated with a substantial reduction in invasive cervical cancer risk, and rotavirus vaccination is recognised as a highly effective tool against severe gastroenteritis and hospitalisation in young children. The economic returns are equally striking: a recent American Academy of Pediatrics policy statement estimates that from 1994 to 2003 vaccination averted 500 million cases of vaccine-preventable disease, 32 million hospitalisations and 1.1 million deaths in the United States, saving 540 billion dollars in direct costs and 2.7 trillion dollars in indirect costs. European studies confirm similar reductions in disease and economic burden, and the World Health Organization has recognised that vaccines also curb antimicrobial resistance by preventing infections that would otherwise require antibiotics.

Yet the academy argues that this evidence base is being undermined by two interacting sets of barriers: access and acceptance. Access barriers include missed opportunities for vaccination during routine health visits, long travel distances and transportation costs in rural or underserved settings, weak follow-up and reminder systems, and limited timeliness in completing vaccine series. Socioeconomic position, maternal education and health literacy shape both the ability to navigate services and the capacity to interpret vaccination information. Marginalised and mobile groups, including migrants, refugees and displaced persons, face additional structural and administrative obstacles, fragmented care and legal and language barriers. Systematic reviews show that migrant and refugee populations in Europe often experience lower vaccination coverage than host populations, and recent register-based evidence among Ukrainian refugee children in Norway illustrates how mobility and incomplete records leave significant gaps in documented immunisation.

Acceptance barriers compound the problem. Parental confidence in vaccines varies between countries and communities and can be weakened by institutional mistrust, pandemic fatigue, inconsistent policy messaging and misinformation. In Europe, false claims are commonly amplified through social media, messaging applications and politicised narratives, gaining traction when families encounter access barriers, receive contradictory advice or perceive vaccine-preventable diseases as remote threats. The academy stresses that effective responses require far more than fact sheets: they demand social listening, pre-bunking and rapid correction of false claims, multilingual community engagement, trusted clinicians and community messengers, and transparent policy decisions visibly aligned with scientific evidence. Vaccine confidence, the paper argues, must be treated as a dynamic challenge that shifts with events rather than a static attitude to be measured once.

The consequences of these immunity gaps are no longer hypothetical. A comprehensive review in The New England Journal of Medicine documented a dramatic resurgence of measles, with more than 395,000 confirmed cases worldwide in 2024 and a further sharp increase in early 2025. Measles is emphatically not a benign childhood illness: it can cause encephalitis, post-infectious immune amnesia and subacute sclerosing panencephalitis, a devastating late complication. In the WHO European Region, more than 127,000 measles cases were recorded in 2024, double the number in 2023 and the highest figure since 1997, with children under five accounting for more than 40 percent of cases and 38 deaths reported. Pertussis has surged in parallel, with nearly 300,000 cases reported in the European Region in 2024, more than a three-fold increase on the previous year. Earlier joint statements by the European Commission, WHO Europe and UNICEF had already linked missed measles vaccination during and after the COVID-19 period to an up to sixty-fold increase in reported cases in 2023 compared with 2022.

The position paper sets out the cost of inaction in stark terms. Epidemiologically, clusters of susceptible children drive recurrent outbreaks, cross-border transmission and avoidable deaths. Individually, children who contract vaccine-preventable diseases may suffer acute illness, hospitalisation, long-term disability or death, along with interrupted education and psychological and financial burdens for families. Economically, outbreaks divert resources from routine care into emergency response, contact tracing, post-exposure prophylaxis and catch-up campaigns. At the system level, failure to invest in surveillance, digital records, workforce training and tailored communication perpetuates a reactive cycle in which gaps are detected late, responses are mounted under pressure, and the same vulnerabilities recur. Beyond the return of disease itself, the academy warns that inaction erodes trust and resilience in preventive child-health systems.

A central technical recommendation concerns documentation. Across Europe, increasing cross-border mobility makes reliable vaccination records essential, yet documentation remains fragmented, often non-digital and non-interoperable, making immunity gaps difficult to detect when children move between health systems. The academy calls for a pan-European digital vaccination-record standard: not a single central database, but an agreed minimum interoperable dataset, mapped to national schedules, protected by data-governance safeguards, and usable in routine care and catch-up vaccination, especially for mobile children and displaced families. It likewise urges expansion of national Immunisation Information Systems capable of real-time or at least quarterly coverage monitoring, detection of missed doses, automated reminders and recalls, and rapid outbreak response. Higher-resource systems may expand such infrastructure directly, while more decentralised or resource-constrained systems may need a staged approach beginning with a core dataset, regional pilots and paper-to-digital transition plans.

Measurement of behavioural barriers is another priority. The academy recommends embedding the WHO Behavioural and Social Drivers of Vaccination tools, the European Centre for Disease Prevention and Control’s 2025 social and behavioural science toolkit, and the Vaccine Barriers Assessment Tool into routine programme assessments, so that interventions are tailored to measured confidence, social norms, practical obstacles and trust rather than generic campaigns. It proposes a minimum monitoring framework tracking coverage for MMR, DTP, polio, HPV and other recommended vaccines by age, geography and equity strata, alongside timeliness, zero-dose and under-immunised children, stock-outs, outbreak incidence, reasons for under-vaccination and the proportion of vaccinators trained in evidence-based communication. Similar proposals have suggested that countries be assessed on their capacity to use social and behavioural data as a fourth indicator in the Joint External Evaluation tool.

Because vaccination is delivered by different professionals across Europe, the recommendations extend beyond paediatricians to general practitioners, nurses, school-health services, public-health teams and community health workers. Preventive paediatric care remains highly heterogeneous across the continent, and not all professionals involved in vaccine delivery have received formal immunisation training. The academy calls for structured education in vaccinology, contraindications, safety communication, motivational interviewing, culturally competent care and outbreak communication, drawing on the WHO Regional Office communication training module and the WHO Pocket book of primary health care for children and adolescents. On the contested question of mandates, the paper holds that compulsory vaccination can be ethically defensible only under strict conditions: when voluntary approaches have failed, disease risk is substantial, access barriers have been addressed, the measure is proportionate, time-limited and legally authorised, and medical exemptions and transparent monitoring protect public trust. Empathetic, patient-centred communication remains the first-line response, supported by narratives of preventable complications that illustrate, but never replace, scientific evidence.

The position paper concludes with a call to shift from high-level advocacy to measurable implementation. It urges harmonised Europe-wide surveillance, interoperable digital records, routine measurement of behavioural and access barriers, equity-focused catch-up schedules that screen for missed doses at primary-care, emergency, school-entry and adolescent contacts, and outreach to migrants, refugees, underserved urban districts and remote rural areas. It also warns that recent legal, regulatory and political shifts, combined with the spread of misinformation, have weakened long-standing protections for immunisation programmes, and that policy choices diverging from scientific evidence can rapidly undermine public health gains. Grounding its appeal in the WHO/UNICEF strategy for child and adolescent health adopted by all 53 Member States of the European Region, the academy frames the issue as a matter of children’s fundamental rights: every child deserves scientifically proven, safe interventions that protect them from avoidable harm. Protecting children today, the paper argues, safeguards the health, trust and resilience of future generations.

Subject of Research: Barriers to paediatric immunisation coverage and strategies to restore childhood vaccination rates in Europe

Article Title: Improving paediatric immunisation coverage rates: a position paper of the European Academy of Paediatrics

Article References: Dornbusch, H. J., Pana, Z. D., Torso, S. D., Hadjipanayis, A., Brierley, J., Karara, N., De Guchtenaere, A., Buttigieg, M., Grossman, Z., Kantor, I., Titomanlio, L., Wyder, C., Jullien, S., Craig, B. J., Pastore, R., Benes, O., Heininger, U., & Koletzko, B. (2026). Improving paediatric immunisation coverage rates: a position paper of the European Academy of Paediatrics. The Lancet Regional Health – Europe, 70, Article 101851. https://doi.org/10.1016/j.lanepe.2026.101851

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DOI: 10.1016/j.lanepe.2026.101851

Keywords: childhood vaccination, vaccine hesitancy, measles, pertussis, European Academy of Paediatrics, immunisation coverage, digital vaccination records, misinformation, vaccine equity, public health, migrant health, Immunisation Information Systems