An evaluation of the surveillance system for monitoring and reporting adverse events following immunization in Kebbi State, Northern Nigeria: a mixed method approach.

Introduction: Despite the benefits of periodic evaluation of the vaccine safety surveillance system, no formal assessment, to our knowledge, has been conducted in Nigeria. Hence, this study evaluated the surveillance system for adverse events following immunization (AEFI) to ascertain the system's functionality to inform vaccine safety considerations and guide communication strategies for demand generation.

Materials And Methods: The study employed a mixed-method approach. Survey questionnaires were administered to 274 routine immunization service providers in Kebbi State, Northern Nigeria, and data were analyzed descriptively using SPSS. In this study, 10 Key Informant Interviews and two Focus Group Discussions were conducted with senior officers and managers at sub-national and national levels within the immunization and surveillance landscape in Nigeria. The interview recordings were cleaned minimally, transcribed, and manually analyzed thematically. Finally, methodological triangulation was done to improve research rigor and provide a better understanding of the phenomena under investigation.

Results: Of the respondents, 201(73.4%) reported that the surveillance system can inform vaccine safety considerations while 170(62%) reported that the AEFI surveillance system can determine the magnitude of AEFI within the population. Further, 173(63%) reported that the surveillance system can provide timely feedback about causality assessment. However, 158(58%) of the respondents stated that the surveillance system is competent in informing communication strategies to improve immunization demand. Triangulation was done which showed dissonance in AEFI surveillance and vaccine safety considerations but partial agreement in immunization demand generation. Further, AEFI surveillance system attributes' triangulation revealed agreements (convergence) on simplicity and timeliness; partial agreements on acceptability, data quality, sensitivity, flexibility, and completeness; dissonance on representativeness and silence on stability, indicating a sub-optimal performance of the AEFI surveillance system in the study setting. Finally, the study unearthed some underlying health system factors impeding the AEFI surveillance system from fully fulfilling its objectives.

Conclusion: The AEFI surveillance system in Northern Nigeria is well established but functioning sub-optimally. Based on the study findings, the capacity to provide information on vaccine safety exists but it is not robust enough to generate sufficient and convincing vaccine safety data and guide communication strategies for vaccine demand generation, especially for new vaccines and those under emergency authorization use.