SMC involves the intermittent administration of a combination of sulfadoxine-pyrimethamine and amodiaquine, known as SPAQ, to children aged three to 59 months during the months when malaria transmission surges. The World Health Organization recommends the approach in areas of the Sahel and surrounding regions where most malaria cases cluster within a few rainy months each year. In South Sudan, where the program was first introduced in 2022, community health workers deliver the medicines door to door in five monthly cycles spaced 28 days apart. Each cycle requires a first dose given under direct observation by the health worker, followed by two further doses that the caregiver must administer at home over the next two days. The full protective effect depends on children receiving all three doses in every one of the five cycles, a benchmark the researchers call cohort retention.

The stakes in South Sudan could hardly be higher. The country recorded an estimated 5.5 million malaria cases in 2025, up from 3.8 million in 2024, and malaria remains the leading cause of illness and death nationwide. Ongoing conflict, widespread poverty, and malnutrition complicate control efforts, while climate change is intensifying flooding and shifting rainfall patterns in ways that are expected to worsen transmission. Northern Bahr el Ghazal, a state of roughly 30,500 square kilometers bordering Sudan, is among the areas where transmission is highly seasonal, peaking between September and November at the end of the rains. It was there, in Aweil West and Aweil South counties, that a research team led by Francis Okot of Malaria Consortium set out to measure how many children stayed the course and why some did not.

The study was conducted in November 2024, one month after the fifth and final cycle of that year’s SMC round. Using multistage random sampling, the team selected 1,500 child-caregiver pairs across 75 clusters, with 40 clusters in Aweil West and 35 in Aweil South, chosen with probability proportional to population size. Trained research assistants, recruited from the local communities and fluent in both English and Dinka, administered a structured questionnaire on smartphones and tablets using the SurveyCTO platform. Caregivers were asked whether their children had received SPAQ in the most recent cycle and in each of the four preceding cycles, whether the first dose had been directly observed, and whether the full three-day course had been completed each time. The survey also captured detailed information on caregiver knowledge, beliefs, education, occupation, and household characteristics.

The statistical approach was carefully chosen to suit the data. Because cohort retention was a highly prevalent outcome, the researchers used modified Poisson regression with robust standard errors rather than conventional logistic regression, which can inflate measures of association when outcomes are common. To account for the clustered sampling design, they fitted mixed-effects models with random intercepts at both the cluster and county levels. The intracluster correlation coefficient was estimated at 0.58, indicating that more than half of the variability in retention was attributable to differences between clusters, and a likelihood ratio test confirmed that the clustered model fit the data significantly better. Model selection proceeded through a stepwise approach, with performance compared using the Akaike and Bayesian information criteria.

The headline result, that 66.9 percent of children were retained across all five cycles, corresponds to a dropout rate of 33.1 percent between the first and final doses of the year. That figure represents an improvement over the 2023 campaign, when only about 20 percent of enrolled children completed all planned cycles, but it still leaves a substantial fraction of children underprotected during the most dangerous months of the year. Evidence from other SMC settings shows that missed doses or dropout during any monthly cycle can substantially reduce the effectiveness of the intervention and raise the prospect of malaria outbreaks. A study in Ghana, for example, documented dropout of 7.43 percent between the first and second cycles, 6.24 percent between the second and third, and 12.34 percent between the third and fourth, illustrating how attrition compounds with each successive round.

What distinguished the children who stayed in the program was not their age or sex, nor their caregivers’ age, gender, or education level, but rather what their caregivers knew and believed. Children whose caregivers were knowledgeable about the purpose of SMC medicines were more than twice as likely to be retained, with an adjusted prevalence ratio of 2.04. Far more striking was the effect of confidence in the medicines themselves: children whose caregivers perceived SMC medicines as effective had nearly five times the prevalence of retention compared with those who did not, an adjusted prevalence ratio of 4.85. Caregivers with paid employment were also significantly more likely to keep their children in the program, with a 28 percent higher prevalence of retention than unemployed caregivers. In the unadjusted analysis, several other factors appeared important, including agricultural work, residence in the area since the campaign began in June 2024, and non-nomadic lifestyle, but these did not retain statistical significance once other variables were accounted for.

The researchers interpret these findings through the lens of the Health Belief Model, which holds that perceived benefits strongly shape whether people follow health advice. Trust in the medicines, they argue, is largely built on understanding why SMC is given and why completing every dose matters. That trust helps ensure children finish the multi-day course even when minor side effects occur, a common reason caregivers abandon regimens elsewhere. The employment effect has a practical logic as well. Caregivers with regular paid work tend to have structured daily routines, more relatives in the household who can stay home on distribution days, and greater financial means to maintain communication tools that track campaign schedules. They are also less likely to migrate seasonally in search of farm work, a pattern of nomadism that frequently causes children to miss scheduled cycles. By contrast, caregivers engaged in agriculture, who made up 65.5 percent of respondents, showed no significant difference in retention from those who were unemployed once other factors were controlled.

Notably, the sociodemographic factors that have predicted retention in studies from Nigeria, Burkina Faso, Chad, and Togo, such as caregiver age and gender roles in household decision-making, showed no significant association in Aweil. The authors suggest that the relatively uniform cultural and social norms of the study population, combined with the door-to-door delivery model that overcomes distance and physical barriers, may have neutralized these effects, allowing knowledge and trust to dominate as drivers of retention. The study had clear strengths, including a large probabilistic sample, multistage sampling to improve representativeness, and rigorous statistical handling of clustering. Its limitations are those inherent to cross-sectional, self-reported surveys: recall bias, social desirability bias, and the potential for translation imprecisions when an English questionnaire was rendered orally into Dinka, a risk the team mitigated by recruiting bilingual assistants from the communities themselves.

The implications reach well beyond South Sudan. SMC is among the most cost-effective malaria interventions available when coverage and adherence are maximized, and experience from Burkina Faso, Mali, and Nigeria shows that strategies such as community health worker follow-up, mobile phone reminders, and caregiver education can meaningfully improve retention. In a setting with constrained health infrastructure and logistical challenges like Northern Bahr el Ghazal, the authors argue for tailored approaches: community sensitization campaigns that explain what SMC does and why every dose counts, engagement of trusted local leaders, flexible distribution schedules that accommodate caregivers’ working hours, and targeted support for families who are unemployed, informally employed, or nomadic. Integrating SMC delivery with immunization or nutrition programs and encouraging local ownership of health initiatives may further strengthen retention. As malaria cases climb in South Sudan and climate pressures intensify, the study’s central message is clear: the medicines exist and the delivery system works, but the intervention’s ultimate success rests on the trust and understanding of the caregivers who administer it, dose by dose, through the rainy season.

Subject of Research: Cohort retention and associated factors in seasonal malaria chemoprevention among children in Northern Bahr el Ghazal, South Sudan

Article Title: Cohort retention in seasonal malaria chemoprevention: an analysis of magnitude and associated factors in Northern Bahr el Ghazal, South Sudan

Article References: Okot, F., Aweno, N., Ikechukwu, E. C., Rom, A., Kabuye, G., Khan, J., Kirabira, A., Dau, A. D., Jacob, A., WApary, E., Katongole, S. P., Mubiru, D., & Nnaji, C. A. (2026). Cohort retention in seasonal malaria chemoprevention: an analysis of magnitude and associated factors in Northern Bahr el Ghazal, South Sudan. Frontiers in Malaria, 4, Article 1913848. https://doi.org/10.3389/fmala.2026.1913848

Image Credits: AI Generated

DOI: 10.3389/fmala.2026.1913848

Keywords: malaria, seasonal malaria chemoprevention, South Sudan, cohort retention, SPAQ, caregivers, medication adherence, child health, public health, community health workers, malaria prevention, Frontiers in Malaria