SARS-CoV-2 antibody prevalence in Sierra Leone, March 2021: a cross-sectional, nationally representative, age-stratified serosurvey
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Abstract
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.
Article activity feed
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Kirsten E Wiens
Review 1: "SARS-CoV-2 Antibody Prevalence in Sierra Leone, March 2021: A Cross-sectional, Nationally Representative, Age-Stratified Serosurvey"
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Strength of evidence
Reviewers: K E Wiens (Johns Hopkins University) | 📗📗📗📗◻️
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SciScore for 10.1101/2021.06.27.21259271: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IACUC: Ethics Approval: The study was approved by the Sierra Leone Ethics and Scientific Review Committee.
IRB: It received a Not Research Determination (IRB20-1394) from the Harvard Institutional Review Board as it was deemed Public Health Surveillance.Sex as a biological variable not detected. Randomization We conducted randomized, multistage sampling, with the first stage of sampling being proportionate to the most recent population size estimate. Blinding not detected. Power Analysis not detected. Cell Line Authentication Authentication: 8 We further validated the test with a control panel of 58 local specimens tested by nasopharyngeal swab, which was comprised of 10 RT-PCR negative, 8 RT-PCR … SciScore for 10.1101/2021.06.27.21259271: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IACUC: Ethics Approval: The study was approved by the Sierra Leone Ethics and Scientific Review Committee.
IRB: It received a Not Research Determination (IRB20-1394) from the Harvard Institutional Review Board as it was deemed Public Health Surveillance.Sex as a biological variable not detected. Randomization We conducted randomized, multistage sampling, with the first stage of sampling being proportionate to the most recent population size estimate. Blinding not detected. Power Analysis not detected. Cell Line Authentication Authentication: 8 We further validated the test with a control panel of 58 local specimens tested by nasopharyngeal swab, which was comprised of 10 RT-PCR negative, 8 RT-PCR positive, and 40 serial dilutions of positives specimens and also found combined IgM/IgG sensitivities and specificities of 100%. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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