Characterising the evolving SARS-CoV-2 seroprevalence in urban and rural Malawi between February 2021 and April 2022: A population-based cohort study

Banda, L. et al. (2023) Characterising the evolving SARS-CoV-2 seroprevalence in urban and rural Malawi between February 2021 and April 2022: A population-based cohort study. International Journal of Infectious Diseases, 137, pp. 118-125. (doi: 10.1016/j.ijid.2023.10.020) (PMCID:PMC10695832)

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Objectives This study aimed to investigate the changing SARS-CoV-2 seroprevalence and associated health and sociodemographic factors in Malawi between February 2021 and April 2022. Methods In total, four 3-monthly serosurveys were conducted within a longitudinal population-based cohort in rural Karonga District and urban Lilongwe, testing for SARS-CoV-2 S1 immunoglobulin (Ig)G antibodies using an enzyme-linked immunosorbent assay. Population seroprevalence was estimated in all and unvaccinated participants. Bayesian mixed-effects logistic models estimated the odds of seropositivity in the first survey, and of seroconversion between surveys, adjusting for age, sex, occupation, location, and assay sensitivity/specificity. Results Of the 2005 participants (Karonga, n = 1005; Lilongwe, n = 1000), 55.8% were female and median age was 22.7 years. Between Surveys (SVY) 1 and 4, population-weighted SARS-CoV-2 seroprevalence increased from 26.3% to 89.2% and 46.4% to 93.9% in Karonga and Lilongwe, respectively. At SVY4, seroprevalence did not differ by COVID-19 vaccination status in adults, except for those aged 30+ years in Karonga (unvaccinated: 87.4%, 95% credible interval 79.3-93.0%; two doses: 98.1%, 94.8-99.5%). Location and age were associated with seroconversion risk. Individuals with hybrid immunity had higher SARS-CoV-2 seropositivity and antibody titers, than those infected. Conclusion High SARS-CoV-2 seroprevalence combined with low morbidity and mortality indicate that universal vaccination is unnecessary at this stage of the pandemic, supporting change in national policy to target at-risk groups.

Item Type:Articles
Additional Information:The study was supported by the Wellcome Trust (grant numbers 217073/Z/19/Z and 221989/Z/20/Z).
Keywords:SARS-CoV-2, seroprevalence, longitudinal cohort, community, Malawi.
Glasgow Author(s) Enlighten ID:Hughes, Ms Ellen and Willett, Professor Brian and Crampin, Professor Mia and Ho, Dr Antonia
Creator Roles:
Ho, A.Conceptualization, Formal analysis, Investigation, Writing – original draft, Writing – review and editing, Visualization, Supervision, Funding acquisition
Hughes, E.Resources
Willett, B.Resources
Crampin, M.Conceptualization, Supervision, Funding acquisition
Authors: Banda, L., Ho, A., Kasenda, S., Read, J. M., Jewell, C., Price, A., McLean, E., Dube, A., Chaima, D., Samikwa, L., Nyirenda, T. S., Hughes, E. C., Willett, B. J., Chauma Mwale, A., Amoah, A. S., and Crampin, A.
College/School:College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
College of Medical Veterinary and Life Sciences > School of Infection & Immunity > Centre for Virus Research
Journal Name:International Journal of Infectious Diseases
ISSN (Online):1878-3511
Published Online:28 October 2023
Copyright Holders:Copyright: © 2023 The Author(s)
First Published:First published in International Journal of Infectious Diseases 137: 118-125
Publisher Policy:Reproduced under a Creative Commons licence

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
306006Healthy Lives - Malawi, Intergenerational family cohort of chronic conditionsAmelia CrampinWellcome Trust (WELLCOTR)217073/Z/19/ZS&PS - Institute of Health & Wellbeing (Social Sciences)
312053SARS-CoV-2 seroepidemiology in Wellcome-funded urban and rural cohorts in Malawi: generating evidence to inform regional medium and long term decision makingAmelia CrampinWellcome Trust (WELLCOTR)221989/Z/20/ZSII - Virology