Malaria , respiratory infections and diarrhoea are the leading causes of hospitalisation and death during the first two years of life in Sierra Leone, according to a prospective study led by ISGlobal, a centre supported by the ”la Caixa” Foundation. The findings, obtained as part of the ICARIA project and published in The Lancet Global Health , show that, despite the implementation of the main preventive strategies currently available , Sierra Leone continues to have one of the highest child mortality rates in the world.
Globally, child mortality has declined substantially over recent decades, but the progress achieved up to 2015 has stalled. In many countries across sub-Saharan Africa, infectious diseases remain one of the greatest threats to survival during the first years of life.
Although Sierra Leone has introduced major public health initiatives—including free healthcare for children under five, malaria chemoprevention , pneumococcal vaccination and, more recently, the malaria vaccine — it remains difficult to assess their impact on survival during the first two years of life . Routine surveillance systems generally group all children under five into a single category, making it difficult to identify accurately the main causes of hospitalisation and death in this age group.
“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,” explains Kwabena Owusu-Kyei , 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 study recorded 2,688 hospital admissions and 859 deaths . Malaria was by far the leading cause of severe illness, accounting for 54.3% of all hospital admissions , followed by lower respiratory infections (16.7%), diarrhoea (9.6%), undernutrition (7.4%) and sepsis (4.8%).
Among deaths occurring in hospitals with available medical records, one in every two was caused by malaria (50.6%) . For deaths occurring outside the hospital, the research team reconstructed the cause of death through standardised interviews with family members or caregivers, a method known as verbal autopsy . Malaria was also the most frequent cause, followed by respiratory infections and diarrhoea , although the researchers note that this method is likely to underestimate malaria mortality because its symptoms overlap with those of other infectious diseases.
The study also identified several factors associated with survival. Children who had received all the routine EPI vaccines due for their age had a 35% lower risk of overall mortality , a 29% lower likelihood of dying during hospital admission, and a 44% lower risk of death after discharge.
In addition, receiving all scheduled doses of sulfadoxine–pyrimethamine, the preventive treatment against malaria delivered through the immunisation programme, was associated with a 40% reduction in mortality risk . Conversely, undernutrition significantly increased the risk of dying during hospitalisation, reinforcing the need to integrate nutritional support into paediatric care.
“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,” concludes Clara Menéndez , Director of ISGlobal’s Maternal, Child and Reproductive Health Programme and principal investigator of the study.
Reference
Owusu-Kyei, K., Cussó, M., Fombah, A. E., Quintó, L., Bofill, A., Morató, A., Fumadó, V., Samai, M., Menéndez, C., & ICARIA Safety Team. (2026). Causes of mortality and severe morbidity in young children in Sierra Leone: a prospective cohort study. The Lancet. Global Health , (104025), 104025. https://doi.org/10.1016/j.langlo.2026.104025
The Lancet Global Health
Observational study
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We declare no competing interests.