RTS, S Malaria Vaccine Uptake and Geographical Disparities among Caregivers in Kisumu County, Kenya: A Cross-Sectional Analysis of Dose Completion (2021–2025)
Abstract
Malaria remains a leading cause of childhood morbidity and mortality in sub-Saharan Africa. The integration of the RTS, S malaria vaccine into routine immunization schedules represents a milestone in malaria control. However, reaching optimal coverage across heterogeneous geographic settings remains a challenge. This study evaluated the uptake levels and dose adherence of the four-dose malaria vaccine regimen among caregivers of children aged 24–36 months across urban and rural settings in Kisumu County, Kenya, between 2021 and 2025. A cross-sectional survey targeting a sample of 260 eligible caregivers was conducted, relying on immunization cards and caregiver recall. Primary metrics evaluated adherence to each dose (Doses 1–4) and overall completion levels (No, Partial, and Full Uptake). Pearson's Chi-Square ( ) test was conducted to examine the association between geographical location and completion status. The results indicate that while initial uptake was high with Dose 1 at 100.0% and Dose 2 at 95.8%. However, adherence dropped significantly for subsequent doses with Dose 3 at 80.7%, and Dose 4 declining to 49.8%. Overall, only 49.6% ( ) achieved full regimen completion, while 50.0% ( ) had partial uptake, and 0.4% ( ) had no uptake. Full uptake was significantly higher in urban areas (54.8%, ) than in rural areas (34.9%, ) ( , , ). Key drop-off drivers included a 15-month gap before the final dose, lack of schedule awareness, vaccine stockouts, and socio-religious barriers. The study concludes that high initial acceptance demonstrates strong community demand, but systemic and geographic barriers hinder complete immunization, particularly in rural settings. Bridging the rural-urban disparity requires targeted reminder systems, community health worker engagement, and optimized vaccine logistics. Keywords: Vaccination, immunization, uptake, dose, children under-five years, caregiver