Safety monitoring of the RTS,S/AS01E malaria vaccine: experiences and lessons from routine pharmacovigilance in Ghana, Kenya, and Malawi

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Abstract Background The pilot implementation of the RTSS/AS01 E (RTS,S) malaria vaccine in Ghana, Kenya, and Malawi marked a significant step in the fight against malaria. Given the scale of the rollout, which far exceeded the controlled environment of clinical trials, establishing a robust pharmacovigilance (PV) system to monitor rare but potentially serious adverse events following immunization (AEFIs) was a critical component of the program’s design. Methods and results In collaboration with technical partners, national health authorities monitored the safety of the RTS,S/AS01 E vaccine through strengthened existing routine pharmacovigilance systems and strategies in the three participating countries. Causality assessment of serious AEFIs by national expert advisory committees did not reveal any new safety concerns associated with the RTS,S/AS01 E vaccine or confirm the safety signals observed in the Phase 3 clinical trials. The PV efforts successfully supported the safe rollout of the vaccine, contributing to substantial public health benefits in these endemic regions. Challenges encountered included underreporting of AEFIs, delays in data submission and in investigating serious AEFIs, and poor report quality despite targeted investments to strengthen the systems. Conclusions and recommendations The pilot program highlighted PV challenges in resource-limited settings and provided useful insights for future vaccine rollouts. The lessons learned from these challenges emphasize the importance of sustained investment, particularly for AEFI investigations, and the need for innovations to improve health worker reporting. Research is needed to identify effective strategies for increasing reporting. Key recommendations include training and capacity building, resource allocation, surveillance and reporting, raising and maintaining public awareness, and collaboration and information sharing to ensure sustained PV efforts and robust safety surveillance in similar contexts.