Neema Mturi

Background Anaemia and malaria are leading causes of paediatric hospitalisation and inpatient mortality in sub-Saharan Africa. However, there is limited empirical data on survival following hospital discharge. We aimed to estimate independent effects of anaemia and malaria parasitaemia on inpatient and 1 year postdischarge mortality among Kenyan children. Methods A retrospective cohort study among children admitted to Kilifi County Hospital (KCH) from 2010 to 2019 and followed-up for 1 year postdischarge in Kilifi Health and Demographic Surveillance System (KHDSS). The main exposures were anaemia and malaria parasitaemia at the time of hospital admission while inpatient and 1 year postdischarge mortality were the outcomes. Results We included 9431 admissions among 7578 children (43% girls), median (IQR) age 19 (9.9‒23) months. 2069 (22%), 3893 (41%) and 1140 (12%) admissions had mild, moderate and severe anaemia, whereas 366 (3.9%), 779 (8.3%) and 224 (2.4%) had low, medium and high malaria parasitaemia, respectively. Overall, there were 381 (4.0%) inpatient deaths: 317/381 (83%) and 47/381 (12%) among children with any level of anaemia and malaria parasitaemia, respectively. Moderate and severe, but not mild anaemia, were positively associated with inpatient death. Low and high level parasitaemia were positively associated with inpatient mortality, while medium level parasitaemia was negatively associated. There were 228 (3.1%) postdischarge deaths: 32.8 (95% CI 28.8‒37.3) deaths/1000 child-years. 180/228 (79%) deaths occurred within 6 months after index discharge and 99/228 (43%) occurred in the community. Overall, 180/228 (79%) and 10/228 (4.4%) postdischarge deaths occurred among children with any level of anaemia and malaria parasitaemia, respectively. Severe anaemia was positively associated with postdischarge mortality (adjusted HR 1.94 (95% CI 1.11‒3.40)), while medium level parasitaemia was negatively associated. Conclusion Interventions to create awareness of postdischarge risks, improve uptake of existing interventions and improved discharge processes targeting high-risk groups such as children admitted with severe anaemia, need to be prioritised.

Background: 10-valent pneumococcal conjugate vaccine (PCV10), delivered at 6, 10 and 14 weeks of age, was introduced in Kenya in January 2011, accompanied by a catch-up campaign in Kilifi County for children <5 years. Coverage with ≥2 PCV10 doses in children 2-11 months was 80% in 2011 and 84% in 2016; coverage with ≥1 dose in children 12-59 months was 66% and 87%, respectively. Methods: Clinical and microbiological surveillance for invasive pneumococcal disease (IPD) among admissions of all ages at Kilifi County Hospital was linked to the Kilifi Health and Demographic Surveillance System from 1999-2016. We calculated the incidence rate ratio (IRR) comparing the pre-vaccine and post-vaccine eras, adjusted for confounding, and reported percent reduction in IPD as 1-IRR. Annual cross-sectional surveys of nasopharyngeal carriage were conducted from 2009-2016. Findings: Surveillance identified 667 IPD cases in 3,211,403 person-years of observation. IPD incidence in children <5 years fell sharply in 2011 following PCV10 introduction, and remained low (PCV10-type IPD: 60·8 vs 3·2/100,000 [92% reduction; 95%CI: 78, 97]; overall IPD: 81·6 vs 15·3/100,000 [68% reduction; 95%CI: 40, 83]; 1999-2010 vs 2012-2016). PCV10-type IPD also declined significantly in unvaccinated age groups (<2 months, 5-14 years, ≥15 years), with estimated reductions of 100%, 74%, and 81%, respectively. There was no significant change in the incidence of non-PCV10 type IPD. In children aged <5 years, PCV10-type carriage declined by 74% and non-PCV10-type carriage increased by 71%. Interpretation: Introduction of PCV10 in Kenya resulted in a substantial reduction in PCV10-type IPD in children and adults without significant replacement disease. These findings suggest that routine infant PCV10 immunization programmes with catch-up campaigns will provide substantial direct and indirect protection in low-income settings in tropical Africa.

Malaria has been a major driving force in the evolution of the human genome. In sub-Saharan African populations, two neighbouring polymorphisms in the Complement Receptor One (CR1) gene, named Sl2 and McC^b, occur at high frequencies, consistent with selection by malaria. Previous studies have been inconclusive. Using a large case-control study of severe malaria in Kenyan children and statistical models adjusted for confounders, we estimate the relationship between Sl2 and McC^b and malaria phenotypes, and find they have opposing associations. The Sl2 polymorphism is associated with markedly reduced odds of cerebral malaria and death, while the McC^b polymorphism is associated with increased odds of cerebral malaria. We also identify an apparent interaction between Sl2 and α⁺thalassaemia, with the protective association of Sl2 greatest in children with normal α-globin. The complex relationship between these three mutations may explain previous conflicting findings, highlighting the importance of considering genetic interactions in disease-association studies.