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. 2021 Nov;6(11):e007271.
doi: 10.1136/bmjgh-2021-007271.

SARS-CoV-2 antibody prevalence in Sierra Leone, March 2021: a cross-sectional, nationally representative, age-stratified serosurvey

Mohamed Bailor Barrie  1   2 , Sulaiman Lakoh  3   4 , J Daniel Kelly  1   5 , Joseph Sam Kanu  4 , James Sylvester Squire  4 , Zikan Koroma  4 , Silleh Bah  6 , Osman Sankoh  6   7   8   9 , Abdulai Brima  6 , Rashid Ansumana  7 , Sarah A Goldberg  5 , Smit Chitre  10 , Chidinma Osuagwu  11 , Raphael Frankfurter  12 , Justin Maeda  13 , Bernard Barekye  13 , Tamuno-Wari Numbere  13 , Mohammed Abdulaziz  13 , Anthony Mounts  14 , Curtis Blanton  14 , Tushar Singh  14 , Mohamed Samai  15 , Mohamed Vandi  4 , Eugene T Richardson  16   13   17
Affiliations

SARS-CoV-2 antibody prevalence in Sierra Leone, March 2021: a cross-sectional, nationally representative, age-stratified serosurvey

Mohamed Bailor Barrie et al. BMJ Glob Health. 2021 Nov.

Abstract

Introduction: As of 26 March 2021, the Africa Centres for Disease Control and Prevention had reported 4 159 055 cases of COVID-19 and 111 357 deaths among the 55 African Union member states; however, no country has published a nationally representative serosurvey as of October 2021. Such data are vital for understanding the pandemic's progression on the continent, evaluating containment measures, and policy planning.

Methods: We conducted a cross-sectional, nationally representative, age-stratified serosurvey in Sierra Leone in March 2021 by randomly selecting 120 Enumeration Areas throughout the country and 10 randomly selected households in each of these. One to two persons per selected household were interviewed to collect information on sociodemographics, symptoms suggestive of COVID-19, exposure history to laboratory-confirmed COVID-19 cases, and history of COVID-19 illness. Capillary blood was collected by fingerstick, and blood samples were tested using the Hangzhou Biotest Biotech RightSign COVID-19 IgG/IgM Rapid Test Cassette. Total seroprevalence was estimated after applying sampling weights.

Results: The overall weighted seroprevalence was 2.6% (95% CI 1.9% to 3.4%). This was 43 times higher than the reported number of cases. Rural seropositivity was 1.8% (95% CI 1.0% to 2.5%), and urban seropositivity was 4.2% (95% CI 2.6% to 5.7%).

Discussion: Overall seroprevalence was low compared with countries in Europe and the Americas (suggesting relatively successful containment in Sierra Leone). This has ramifications for the country's third wave (which started in June 2021), during which the average number of daily reported cases was 87 by the end of the month:this could potentially be on the order of 3700 actual infections per day, calling for stronger containment measures in a country with only 0.2% of people fully vaccinated. It may also reflect significant under-reporting of incidence and mortality across the continent.

Keywords: COVID-19; Serology.

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Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Daily COVID cases in Sierra Leone until from Feb 1, 2020 to June 30, 2021. The country’s first case was reported on March 31, 2020. (Source: COVID-19 Dashboard by the by the Center for Systems Science and Engineering at Johns Hopkins University. Accessed July 2, 2021).
See this image and copyright information in PMC

Update of

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