Evaluation report
The Malaria Vaccine Programme Evaluation in Kenya: results of a baseline household survey prior to the introduction of the RTS,S/AS01 vaccine.
Nelli Westercamp, Isabella Nyangau, Titus K Kwambai, Brian Seda, Dorcas Akach et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This baseline survey in western Kenya measured malaria burden and health service coverage in children aged 5-48 months before introducing the RTS,S malaria vaccine in 2019. Malaria prevalence was 22% overall with significant geographic variation. While vaccination coverage for first-year vaccines exceeded 85%, coverage dropped substantially for second-year services like measles dose 2 (49%) and other interventions like vitamin A (46%) and deworming (50%). Nearly all caregivers were willing to accept the malaria vaccine despite only 36% having heard of it beforehand.
Key points
- P. falciparum malaria prevalence was 22% overall with substantial sub-county variation (1-71%), higher in rural areas and lower wealth households
- Insecticide-treated net ownership and use were high at 93% and 87% respectively
- First-year-of-life vaccination coverage exceeded 85%, but measles dose 2 coverage was only 49%
- Vitamin A supplementation and deworming coverage were suboptimal at 46% and 50%
- Only 36% of caregivers had heard of the malaria vaccine before introduction, yet 98% expressed willingness to vaccinate
Limitations
This is a baseline survey conducted before vaccine introduction, so it cannot measure the vaccine's actual impact on malaria outcomes or assess the feasibility of delivering the 4-dose schedule. The baseline imbalance between vaccine introduction and comparison areas may affect subsequent impact evaluations.
Abstract
BACKGROUND: In September 2019, Kenya began pilot introduction of the RTS,S/AS01E (RTS,S) malaria vaccine through the World Health Organization (WHO)-coordinated Malaria Vaccine Implementation Programme (MVIP). The pilot, conducted in 46 sub-counties in western Kenya with moderate-to-high perennial malaria transmission, aimed to assess feasibility of delivering the 4-dose schedule through routine immunization services, vaccine safety, and impact on mortality and severe malaria admissions. This paper presents findings from the baseline household survey conducted prior to vaccine introduction to characterize malaria burden, coverage of malaria control interventions, health-seeking behaviors, immunization coverage, and caregiver perceptions of RTS,S. METHODS: A cross-sectional, population-representative household survey was conducted from July to October 2019 in all 46 MVIP sub-counties. Using two-stage cluster sampling, 4065 households were enrolled, including 4948 children aged 5-48 months. Structured questionnaires captured data on insecticide-treated net (ITN) ownership and use, vaccination status, recent febrile illness and care-seeking, and vaccine acceptability. Malaria rapid diagnostic tests were performed to estimate malaria prevalence. Analyses accounted for cluster design and sampling weights. RESULTS: Overall P. falciparum malaria prevalence was 22% (95% CI 19-26), with substantial sub-county variation (1-71%). Prevalence was higher in rural areas, among older children, in lower wealth households, and in areas randomized to vaccine introduction vs. comparison areas, indicating baseline imbalance between the arms. ITN ownership and use were high (93% and 87%). Thirty-eight percent of children had fever in the prior two weeks; 70% sought care, 39% of whom received antimalarials, nearly all artemisinin-combined therapies. Availability of home-based vaccination records declined with age (93% among 5-11 months vs. 63% among 36-48 months). Coverage exceeded 85% for first-year-of-life vaccines, but was lower for measles dose 2 (49%). Vitamin A supplementation (46%) and deworming (50%) coverage were also suboptimal. Before introduction, only 36% of caregivers had heard of the malaria vaccine, yet willingness to vaccinate exceeded 98%. CONCLUSIONS: High malaria burden, strong coverage of core interventions, and strong caregiver support provided a favorable context for RTS,S introduction. However, gaps in second-year-of-life services and suboptimal vaccination records retention may challenge delivery and monitoring of the 4th RTS,S dose. These findings establish a benchmark for evaluating RTS,S rollout and integration into routine child health services. Trial registration number NCT03806465.