Vaccine safety surveillance in South Africa through COVID-19 : a journey to systems strengthening

Abstract

BACKGROUND : Surveillance systems for monitoring and reporting adverse events following immunisation (AEFI) and adverse events of special interest (AESI) are vital in understanding safety profiles of post-marketed vaccines. Evaluation of surveillance systems is necessary for systems strengthening. We conducted the first evaluation of the South African AEFI surveillance system in its current form, established in 2018. METHODS : Using CDC guidelines for evaluation of surveillance systems, we conducted a cross-sectional evaluation of system attributes, including quantitative analyses of AEFI/AESI data from 17 May 2021 to 31 December 2022 and qualitative analyses through semi-structured interviews with AEFI surveillance personnel. Findings were used to generate recommendations for system strengthening. RESULTS : The system collects and manages AEFI data, employs investigative tools and has an established AEFI review committee conducting causality assessment, thus meeting WHO minimal capacity for vaccine safety. System adaptation through inclusion of digital applications facilitated public reporting, whilst increasing complexity of database management. Respondents demonstrated engagement with the system through accounts of their roles in AEFI surveillance. Between 17 May 2021 and 31 December 2022, 37,537,009 COVID-19 vaccine doses (BNT162b2 and Ad26.COV2·S) were administered, and 3846 AEFI reported in relation to these vaccines (reporting rate: 10.2/100,000 doses). AEFI reporting rates varied considerably across provinces, ranging from 1.6 to 59.5 AEFI/100,000 doses. In this time period 283 AEFI were reported in relation to non-COVID-19 vaccines. By 31 December 2022, 73.5 % of severe cases that were investigated were causality assessed. CONCLUSION : We observed a functional, useful, flexible system with high reported stakeholder and public acceptability levels. System challenges included low reporting rates from particular provinces, weak co-ordination between paper and digital reporting and human resource constraints. Recommendations include integration of paper-based and digital surveillance reporting systems to enhance signal detection and eliminate data duplication, provision of dedicated human and financial resources at provincial level and inclusion of active AEFI surveillance through cohort event monitoring.