SARS-CoV-2 Case Detection Using Community Event-Based Surveillance System – February to September 2020: Lessons Learned from Senegal

Background: Within 10 months of the first global case, the SARS-CoV-2 outbreak resulted in over 15,000 positive cases and more than 500 deaths in Senegal. We describe the design and implementation of a community EBS (CEBS) system in Senegal and how it contributed to strengthening the country's surveillance system during the COVID-19 pandemic. Methodology: We examined data collected from COVID-19 specific phone calls within a CEBS system serving 14 regions of Senegal over the period from February to September 2020. We abstracted data on call origin, residence information, call status (validated or non-validated) and linked it to laboratory-confirmed cases from the national system. The number of calls received were mapped to positive cases of SARS-CoV-2by week. We used Excel for data analysis. Results: A total of 10,751 out of 10,760 calls received were COVID-19 calls from all 14 regions in Senegal. The majority of the COVID-19 calls were from the Dakar (84.8%: 9,117/10,751) and Thies (7.4%: 801/10,751) regions. Of the COVID-19 calls, 50.2% (5402/10751) were validated and sent to the health district for investigation. Only 25% (1354/5402) of the validated calls were positive cases of SARS-CoV-2. The highest number of positive SARS-Cov-2 cases were reported from the Dakar (85%, 1152/1354) and Thies (8%, 104/1354) regions. The volume of COVID-19 calls increased after the first lab-confirmed case during week 10 (March 2020) through week 20 to 24 (June 2020) and eventually tapered off during week 28 (July 2020). Conclusion: COVID-19 accelerated EBS system implementation in Senegal. Implementation of the CEBS contributed to the identification of positive cases of SARS-CoV-2; however, operational challenges such as missing data, incomplete information, and lack of system linkage persist. Consideration of these challenges can guide improvements and facilitate the successful implementation of EBS systems during a pandemic in Senegal and elsewhere.