tetano
Editor, Senior Moderator
Int J Infect Dis
. 2023 Dec:137:118-125.
doi: 10.1016/j.ijid.2023.10.020. Epub 2023 Oct 28. Characterizing the evolving SARS-CoV-2 seroprevalence in urban and rural Malawi between February 2021 and April 2022: A population-based cohort study
Louis Banda[SUP] 1 [/SUP], Antonia Ho[SUP] 2 [/SUP], Stephen Kasenda[SUP] 1 [/SUP], Jonathan M Read[SUP] 3 [/SUP], Chris Jewell[SUP] 3 [/SUP], Alison Price[SUP] 4 [/SUP], Estelle McLean[SUP] 4 [/SUP], Albert Dube[SUP] 1 [/SUP], David Chaima[SUP] 5 [/SUP], Lyson Samikwa[SUP] 5 [/SUP], Tonney S Nyirenda[SUP] 5 [/SUP], Ellen C Hughes[SUP] 6 [/SUP], Brian J Willett[SUP] 6 [/SUP], Annie Chauma Mwale[SUP] 7 [/SUP], Abena S Amoah[SUP] 8 [/SUP], Amelia Crampin[SUP] 9 [/SUP]
Affiliations
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.
Keywords: Community; Longitudinal cohort; Malawi; SARS-CoV-2; Seroprevalence.
. 2023 Dec:137:118-125.
doi: 10.1016/j.ijid.2023.10.020. Epub 2023 Oct 28. Characterizing the evolving SARS-CoV-2 seroprevalence in urban and rural Malawi between February 2021 and April 2022: A population-based cohort study
Louis Banda[SUP] 1 [/SUP], Antonia Ho[SUP] 2 [/SUP], Stephen Kasenda[SUP] 1 [/SUP], Jonathan M Read[SUP] 3 [/SUP], Chris Jewell[SUP] 3 [/SUP], Alison Price[SUP] 4 [/SUP], Estelle McLean[SUP] 4 [/SUP], Albert Dube[SUP] 1 [/SUP], David Chaima[SUP] 5 [/SUP], Lyson Samikwa[SUP] 5 [/SUP], Tonney S Nyirenda[SUP] 5 [/SUP], Ellen C Hughes[SUP] 6 [/SUP], Brian J Willett[SUP] 6 [/SUP], Annie Chauma Mwale[SUP] 7 [/SUP], Abena S Amoah[SUP] 8 [/SUP], Amelia Crampin[SUP] 9 [/SUP]
Affiliations
- PMID: 38465577
- PMCID: PMC10695832
- DOI: 10.1016/j.ijid.2023.10.020
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.
Keywords: Community; Longitudinal cohort; Malawi; SARS-CoV-2; Seroprevalence.