Abstract / Summary
Abstract Background Cameroon was the first African country to introduce the RTS,S/AS01 malaria vaccine into its Expanded Programme on Immunisation on 22 January 2024, using a four-dose schedule (6, 7, 9 and 24 months). Surveillance of adverse events following immunization (AEFI) is essential to assess vaccine safety under real-world conditions. This study describes AEFI notified in three pilot districts of the Littoral Region. Methods We conducted a descriptive cross-sectional analysis of routine DHIS2 data from Monthly Activity Reports of health facilities, from January 2024 to August 2026, in the districts of Edea, Japoma and Mbanga. The variables analysed were serious and non-serious AEFI, as well as doses administered used as denominator. Notification rates per 1,000 doses were calculated with 95% confidence intervals using the exact Poisson method. Results A total of 295 AEFI were notified, of which 288 were non-serious (97.6%) and 7 were serious (2.4%). The Japoma district accounted for 210 AEFI (71.2%), including 124 non-serious cases in 2025. The overall AEFI rate ranged from 1.13 to 12.06 per 1,000 doses administered depending on district and year. Serious AEFI were rare and dispersed (Edea: 1; Mbanga: 3; Japoma: 3), with no temporal or spatial clustering. Conclusions The safety profile of RTS,S/AS01 in the three pilot districts appears favourable. The increase in non-serious AEFI in Japoma in 2025 suggests improved sensitivity of the surveillance system rather than a safety signal. Strengthening causality assessment and standardizing notifications remain necessary.