Silent Spread of SARS-CoV-2 in Ethiopia: Longitudinal Cohort Study Among Frontline Healthcare Workers and Community

Background: Over a year since the first reported case, COVID-19 burden in Ethiopia remains unknown due to limited surveillance. We aimed to investigate seroepidemiology of SARS-CoV-2 among frontline healthcare workers (HCW) and communities in Ethiopia. Methods: We conducted a population-based, prospective, longitudinal cohort study involving HCW, urban residents, and rural communities in Jimma and Addis Ababa. Serology was performed with Elecsys® Anti-SARS-CoV-2 anti-nucleocapsid assay (Roche Diagnostics, Switzerland) in three consecutive rounds with a mean interval of six weeks between tests to obtain seroprevalence and incidence estimates within the cohorts. Findings: SARS-CoV-2 seroprevalence among HCW increased dramatically during the study period: in Addis Ababa from 10·9% (95% Credible Interval: 8·3%; 13·8%) in August 2020 to 53·7% (44·8; 62·5) in February 2021, incidence rate 2,223 (1,785; 2,696) per 100,000 person-weeks; in Jimma from 30·8% (26·9; 34·8) in November 2020 to 56·1% (51·1; 61·1) in February 2021, incidence rate 3,810 (3,149; 4,540) per 100,000 person-weeks. Among urban communities, an almost 40% increase in seroprevalence was observed in early 2021, with incidence rates of 1,622 (1,004; 2,429) in Jimma and 4,646 (2,797; 7,255) per 100,000 person-weeks in Addis Ababa.  Seroprevalence in rural communities increased from 18·0% (13·5, 23·2) in November 2020 to 31·0% (22·3, 40·3) in March 2021. Interpretation: SARS-CoV-2 spread in Ethiopia has been highly dynamic among HCW and urban communities. It can be speculated that the greatest wave of SARS-CoV-2 infections is currently evolving in rural Ethiopia and thus requires focused attention in respect to healthcare burden and disease prevention. Funding Information: Bavarian State Ministry of Sciences, Research and the Arts (Bayerisches Staatsministerium, F.4-V0122.4/3/20), Germany Ministry of Education and Research (MoKoCo19; 01KI20271), EU Horizon2020 program (ORCHESTRA; 101016167), Deutsche Forschungsgemeinschaft (SEPAN; HA 7376/3-1), Volkswagenstiftung (E2; 99450). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: This research was approved by the institutional review boards of (i) the Jimma University Institute of Health, (ii) St. Paul’s Hospital Millennium Medical College, and (iii) Ludwig Maximilian University of Munich. Additional approvals were obtained from Addis Ababa and Oromia Regional Health Bureaus. Written informed consent was obtained from all participants.