The study’s central conclusion is stark: the majority of hospitalisations and deaths among children in their first two years of life are caused by infectious diseases that are, in principle, preventable. Malaria alone accounted for 54.3 percent of all hospital admissions recorded during the follow-up period, dwarfing every other cause of severe illness. Lower respiratory infections ranked second at 16.7 percent of admissions, followed by diarrhoeal disease at 9.6 percent, undernutrition at 7.4 percent and sepsis at 4.8 percent. Among deaths that occurred in hospitals with available medical records, malaria was responsible for 50.6 percent, meaning that one in every two in-hospital deaths in this age group was attributable to a single parasitic disease transmitted by mosquitoes.

The burden extends beyond hospital walls. For children who died outside medical facilities, the research team reconstructed probable causes of death through standardised interviews with family members and caregivers, a well-established epidemiological technique known as verbal autopsy. This analysis likewise identified malaria as the most frequent cause of death, followed by respiratory infections and diarrhoea. The researchers caution, however, that verbal autopsy is likely to underestimate malaria mortality, because the fever and generalised symptoms characteristic of severe malaria overlap considerably with those of other common infectious diseases, making it difficult for bereaved caregivers to distinguish between them when recalling a child’s final illness.

The scale and precision of the study distinguish it from previous efforts to characterise early childhood disease burden in the region. Routine surveillance systems in Sierra Leone and many other countries typically group all children under five into a single reporting category, a practice that obscures the distinct epidemiology of infancy and early toddlerhood and makes it difficult to identify precisely which conditions drive hospitalisation and death at different ages. To close this gap, the ICARIA team combined continuous health facility surveillance with household visits, telephone follow-up and a network of community informants, creating an unusually complete record of both severe illness and mortality across the first two years of life.

“To address this important knowledge gap, we followed 20,560 infants up to 24 months of age across 14 health centres in three districts of Sierra Leone,” explained Kwabena Owusu-Kyei, an ISGlobal researcher based in Sierra Leone and first author of the study. “By combining health facility surveillance with household visits, telephone follow-up and community informants, we were able to build a much more complete picture of childhood hospitalisations and deaths.” During the follow-up period, the cohort recorded 2,688 hospital admissions and 859 deaths, figures that translate into an extraordinary concentration of severe disease in a population of children who had, by the study’s design, access to facilities offering free healthcare.

The context of Sierra Leone’s public health landscape makes the findings all the more consequential. Over the past decade and a half, the country has introduced a series of major initiatives aimed at reducing child deaths, including a policy of free healthcare for children under five, malaria chemoprevention programmes, pneumococcal vaccination and, more recently, the rollout of the malaria vaccine. Yet until now, it has been difficult to assess how these interventions are affecting survival during the first two years of life, the period when children are most vulnerable to the infectious diseases that dominate the region’s disease burden. The new study provides the granular evidence base that such assessments require.

Beyond quantifying the burden of disease, the study identified several factors strongly associated with a child’s chances of survival, offering concrete targets for intervention. Children who had received all the routine vaccines of the Expanded Programme on Immunization (EPI) due for their age had a 35 percent lower risk of overall mortality compared with incompletely vaccinated children. Complete vaccination was also associated with a 29 percent lower likelihood of dying during a hospital admission and, strikingly, a 44 percent lower risk of death in the period after discharge from hospital, a finding that underscores how vaccination status shapes resilience well beyond the immediate protection conferred against specific vaccine-preventable pathogens.

Malaria chemoprevention also emerged as a powerful protective factor. Children who received all scheduled doses of sulfadoxine–pyrimethamine, the preventive antimalarial treatment delivered through Sierra Leone’s immunisation programme, had a 40 percent reduction in mortality risk compared with those who missed doses. Conversely, undernutrition significantly increased the risk of dying during hospitalisation, a result that reinforces long-standing calls to integrate nutritional support into paediatric care rather than treating malnutrition and infectious disease as separate clinical problems. Taken together, these associations suggest that the tools needed to save young lives largely already exist within the health system, but that coverage, adherence and integration remain insufficient.

The study arrives at a moment of broader concern for global child health. Worldwide, child mortality has declined substantially over recent decades, one of the great public health achievements of the modern era, but the progress achieved up to 2015 has since stalled. In many countries across sub-Saharan Africa, infectious diseases remain among the greatest threats to survival during the first years of life, and the stagnation of mortality declines suggests that existing strategies are not reaching their full potential. Sierra Leone, still rebuilding its health system after decades of civil war and the 2014 Ebola epidemic, exemplifies the challenge facing the world’s most vulnerable settings.

“These findings show that there is still a substantial unfinished agenda in global health, and that strengthening vaccination, malaria prevention, community-based care and post-discharge follow-up are essential to reducing child mortality in the world’s most vulnerable settings and meeting the Sustainable Development Goals,” concluded Clara Menéndez, Director of ISGlobal’s Maternal, Child and Reproductive Health Programme and principal investigator of the study. With the Sustainable Development Goal target of ending preventable deaths of newborns and children under five by 2030 drawing closer, the Sierra Leone cohort offers both a warning and a roadmap: the diseases killing the youngest children are known, the preventive tools are available, and the decisive variable is whether they reach every child who needs them.

Subject of Research: Causes of hospitalisation and death from malaria and other infectious diseases in children under two in Sierra Leone

Article Title: Malaria remains the leading cause of hospital admission and in-hospital death in children under two in Sierra Leone

Article References: Malaria remains the leading cause of hospital admission and in-hospital death in children under two in Sierra Leone. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: malaria, child mortality, Sierra Leone, The Lancet Global Health, ISGlobal, ICARIA project, vaccination, chemoprevention, sulfadoxine-pyrimethamine, undernutrition, respiratory infections, verbal autopsy