Rapidly Increasing Severe Acute Respiratory Syndrome Coronavirus 2 Seroprevalence and Limited Clinical Disease in 3 Malian Communities: A Prospective Cohort Study

  1. Issaka Sagara
  2. John Woodford
  3. Mamady Kone
  4. Mahamadoun Hamady Assadou
  5. Abdoulaye Katile
  6. Oumar Attaher
  7. Amatigue Zeguime
  8. M’Bouye Doucoure
  9. Emily Higbee
  10. Jacquelyn Lane
  11. Rathy Mohan
  12. Justin Doritchamou
  13. Irfan Zaidi
  14. Dominic Esposito
  15. Jennifer Kwan
  16. Kaitlyn Sadtler
  17. Alassane Dicko
  18. Patrick E Duffy

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Abstract

Background

The extent of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exposure and transmission in Mali and the surrounding region is not well understood. We aimed to estimate the cumulative incidence of SARS-CoV-2 in 3 communities and understand factors associated with infection.

Methods

Between July 2020 and January 2021, we collected blood samples and demographic, social, medical, and self-reported symptoms information from residents aged 6 months and older over 2 study visits. SARS-CoV-2 antibodies were measured using a highly specific 2-antigen enzyme-linked immunosorbent assay optimized for use in Mali. We calculated cumulative adjusted seroprevalence for each community and evaluated factors associated with serostatus at each visit by univariate and multivariate analysis.

Results

Overall, 94.8% (2533/2672) of participants completed both study visits. A total of 31.3% (837/2672) were aged <10 years, 27.6% (737/2672) were aged 10–17 years, and 41.1% (1098/2572) were aged ≥18 years. The cumulative SARS-CoV-2 exposure rate was 58.5% (95% confidence interval, 47.5–69.4). This varied between sites and was 73.4% in the urban community of Sotuba, 53.2% in the rural town of Bancoumana, and 37.1% in the rural village of Donéguébougou. Study site and increased age were associated with serostatus at both study visits. There was minimal difference in reported symptoms based on serostatus.

Conclusions

The true extent of SARS-CoV-2 exposure in Mali is greater than previously reported and may now approach hypothetical “herd immunity” in urban areas. The epidemiology of the pandemic in the region may be primarily subclinical and within background illness rates.

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  1. Version published to 10.1093/cid/ciab589
  2. ScreenIT

    SciScore for 10.1101/2021.04.26.21256016: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: Ethics Statement: The study was conducted as a Public Health surveillance activity in collaboration with the Malian Ministry of Health and was approved by the ethics committee of Facultes de Medicine/d’Odonto-Stomatologie et de Pharmacie (2020/114/CE/FMOS/FAPH) and the Malian COVID-19 Scientific Review Committee.
    Consent: Written informed consent or assent was obtained from all participants before enrollment in the study.
    Sex as a biological variableIn female participants, pregnancy status was recorded.
    Randomizationnot detected.
    Blindingnot detected.
    Power AnalysisStatistical analysis: The study sample size was based on pragmatic factors.

    Table 2: Resources

    Antibodies
    SentencesResources
    We assessed individuals aged 6 months or older from three communities in Mali for anti-SARS-CoV-2 antibodies.
    anti-SARS-CoV-2
    suggested: None
    Sera separated from blood samples collected at each visit were tested for the presence of IgG antibodies to SARS-CoV-2 spike protein and receptor binding domain (RBD) at the MRTC/DEAP Immunology Laboratory using a reference ELISA adapted for optimized performance in the local population [6, 14].
    SARS-CoV-2 spike protein and receptor binding domain (RBD
    suggested: None
    Software and Algorithms
    SentencesResources
    Data were collected and stored using REDCap.
    REDCap
    suggested: (REDCap, RRID:SCR_003445)
    Statistical analysis was performed with Microsoft Excel and Graphpad Prism 9 software.
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)
    Graphpad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    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: We detected the following sentences addressing limitations in the study:
    Our study has several limitations, including a sample size that is not sufficient to determine the rate of uncommon severe outcomes in the community, and the risk of recall bias in reported symptoms history. In our study, reported symptoms history was similar in the overall study population to adverse events recorded for a subpopulation co-enrolled in parallel clinical trials. Furthermore we would expect recall bias to be similar between seropositive and seronegative participants. The study population was not selected randomly, and therefore there is also a risk of selection bias. Notably, no participant reported a personal history of prior COVID-19 diagnosis or household member with a diagnosis at enrollment, and there was a high proportion of community participation, particularly at the Donéguébougou site. The evidence here of high community seroprevalence can inform prioritization and implementation of vaccination programs in populations with a young age structure and limited evidence of substantial clinical disease. Information on circulating virus variants will also be valuable to decision-making, as efficacy of any available vaccines may vary against locally circulating variants. This study provides further evidence that Africa has not been spared by SARS-CoV-2, and that the epidemiology of disease in Malian communities may be primarily subclinical and within background illness rates. In this setting, community mitigation strategies may differ to other regions, and ongo...

    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.

    About SciScore

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  3. Version published to 10.1101/2021.04.26.21256016v1 on medRxiv