Supplementary file 1_Event-based surveillance in the WHO African region: baseline implementation before the COVID-19 pandemic.zip

Event-based surveillance (EBS) is a critical component of epidemic intelligence, supporting the timely detection of unusual public health events. However, prior to the COVID-19 pandemic, the status of EBS implementation across the WHO African region was not well documented. This study establishes a regional baseline of EBS modalities in place before the pandemic to inform future surveillance system evaluation and strengthening. We conducted a cross-sectional survey across all 47 WHO Member States in the African region between December 2019 and February 2020. A structured questionnaire was disseminated through WHO Country Offices to assess the presence, characteristics, and functionality of EBS modalities—including health facility-based EBS (HEBS), community-based surveillance (CBS), and media monitoring. Quantitative data were analyzed descriptively, while qualitative responses underwent thematic analysis. Thirty-seven countries (78.7%) responded, of which 84% (n = 31) had implemented at least one form of EBS. HEBS was the most commonly reported modality (67.6%), followed by CBS (54.1%) and media monitoring (29.7%). Cholera, acute flaccid paralysis, measles, and meningitis were the most frequently detected conditions. While mobile phones were the primary channel for reporting, challenges included resource constraints and infrastructure gaps. Radio was the most widely used media source due to limited access to internet-based tools. Countries widely recognized EBS as a national priority but cited the need for sustainable financing, tools, and trained personnel. By early 2020, most countries in the region had adopted EBS, though implementation varied in scope and maturity. The COVID-19 pandemic catalyzed expansion of many modalities, offering an opportunity to institutionalize gains. Strengthening EBS systems will require sustained investment, intersectoral coordination, and context-appropriate tools aligned with national capacities.