Seroprevalence survey of anti-SARS-CoV-2 antibody and associated factors in South Africa: Findings of the 2020-2021 population-based household survey

Sizulu Moyo; Leickness C Simbayi; Khangelani Zuma; Nompumelelo Zungu; Edmore Marinda; Sean Jooste; Shandir Ramlagan; Mirriam Fortuin; Beverley Singh; Musawenkosi Mabaso; Tarylee Reddy; Whadi-Ah Parker; Inbarani Naidoo; Samuel Manda; Ameena Goga; Nobubelo Ngandu; Cherie Cawood; Penny L Moore; Adrian Puren

doi:10.1371/journal.pgph.0002358

Seroprevalence survey of anti-SARS-CoV-2 antibody and associated factors in South Africa: Findings of the 2020-2021 population-based household survey

PLOS Glob Public Health. 2023 Sep 25;3(9):e0002358. doi: 10.1371/journal.pgph.0002358. eCollection 2023.

Authors

Sizulu Moyo^{1

2}, Leickness C Simbayi^{1

3}, Khangelani Zuma^{1

4}, Nompumelelo Zungu^{1

5}, Edmore Marinda^{1

4}, Sean Jooste¹, Shandir Ramlagan¹, Mirriam Fortuin⁶, Beverley Singh⁶, Musawenkosi Mabaso¹, Tarylee Reddy⁷, Whadi-Ah Parker¹, Inbarani Naidoo¹, Samuel Manda⁷, Ameena Goga^{7

8}, Nobubelo Ngandu⁷, Cherie Cawood⁹, Penny L Moore^{6

10}, Adrian Puren^{6

11}

Affiliations

¹ Human Sciences Research Council, Pretoria, South Africa.
² School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.
³ Department of Psychiatry & Mental Health, University of Cape Town, Cape Town, South Africa.
⁴ School of Public Health, University of the Witwatersrand, Johannesburg, South Africa.
⁵ Department of Psychology, University of Pretoria, Pretoria, South Africa.
⁶ National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa.
⁷ Biostatistics Research Unit (TR and SMa)/ HIV and other Infectious Diseases Research Unit (AG and NN), South African Medical Research Council, Cape Town, South Africa.
⁸ Department of Paediatrics and Child Health, University of Pretoria, Pretoria, South Africa.
⁹ Epicentre, Randburg, South Africa.
¹⁰ SAMRC Antibody Immunity Research Unit, Division of Virology and Immunology, University of the Witwatersrand, Johannesburg, South Africa.
¹¹ Division of Virology, School of Pathology, University of the Witwatersrand Medical School, Johannesburg, South Africa.

Abstract

Population-based serological testing is important to understand the epidemiology and estimate the true cumulative incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to inform public health interventions. This study reports findings of a national household population SARS-CoV-2 serosurvey in people 12 years and older in South Africa. This cross-sectional multi-stage random stratified cluster survey undertaken from November 2020 to June 2021 collected sociodemographic data, medical history, behavioural data, and blood samples from consenting participants. The samples were tested for SARS-CoV-2 antibodies using the Roche ElecsysAnti-SARS-CoV-2 chemiluminescence immunoassay (CLIA) Total Antibody Test. The survey data were weighted by age, race, sex, and province with final individual weights benchmarked against the 2020 mid-year population estimates and accounted for clustering. Descriptive statistics summarize the characteristics of participants and seroprevalence. Logistic regression analyses were used to identify factors associated with seropositivity. From 13290 survey participants (median age 33 years, interquartile range (IQR) 23-46 years), SARS-CoV-2 seroprevalence was 37.8% [95% Confidence Interval (CI) 35.4-40.4] and varied substantially across the country's nine provinces, and by sex, age and locality type. In the final adjusted model, the odds of seropositivity were higher in women than in men [aOR = 1.3 (95% CI: 1.0-1.6), p = 0.027], and those living with HIV (self-report) [aOR = 1.6 (95% CI: 1.0-2.4), p = 0.031]. The odds were lower among those 50 years and older compared to adolescents 12-19 years old [aOR = 0.6 (95% CI: 0.5-0.8), p<0.001] and in those who did not attend events or gatherings [aOR = 0.7 (95% CI: 0.6-1.0), p = 0.020]. The findings help us understand the epidemiology of SARS-CoV-2 within different regions in a low-middle-income country. The survey highlights the higher risk of infection in women in South Africa likely driven by their home and workplace roles and also highlighted a need to actively target and include younger people in the COVID-19 response.

Copyright: © 2023 Moyo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Grants and funding

The study was funded, by the Solidarity Fund, South Africa (SM, LCS, KZ, NZ, EM, SJ, WP, SR, IN, MM, CC, TR, Sma, CC, PLM, AP, AM, NG, BS, LM, MF, NCAS Study Team), the Human Sciences Research Council, South Africa (SM, LCS, KZ, NZ, EM, SJ, WP, SR, IN, MM,) and the National Institute for Communicable Diseases, South Africa (AP, BS, MF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.