COVID-19 Vaccine Uptake and Effectiveness by Time since Vaccination in the Western Cape Province, South Africa: An Observational Cohort Study during 2020–2022
Reshma Kassanjee,
Mary-Ann Davies,
Alexa Heekes,
Hassan Mahomed,
Anthony J. Hawkridge,
Erna Morden,
Theuns Jacobs,
Cheryl Cohen,
Harry Moultrie,
Richard J. Lessells,
Nicolette Van Der Walt,
Juanita O. Arendse,
Nicole Wolter,
Sibongile Walaza,
Waasila Jassat,
Anne von Gottberg,
Patrick L. Hannan,
Daniel R. Feikin,
Keith Cloete,
Andrew Boulle
Affiliations
Reshma Kassanjee
Centre for Infectious Disease Epidemiology and Research, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
Mary-Ann Davies
Centre for Infectious Disease Epidemiology and Research, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
Alexa Heekes
Centre for Infectious Disease Epidemiology and Research, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
Hassan Mahomed
Division of Health Systems and Public Health, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa
Anthony J. Hawkridge
Rural Health Services, Western Cape Department of Health and Wellness, Cape Town 8000, South Africa
Erna Morden
Health Intelligence, Western Cape Department of Health and Wellness, Cape Town 8000, South Africa
Theuns Jacobs
Health Intelligence, Western Cape Department of Health and Wellness, Cape Town 8000, South Africa
Cheryl Cohen
Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
Harry Moultrie
Centre for Tuberculosis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
Richard J. Lessells
KwaZulu-Natal Research Innovation & Sequencing Platform, University of KwaZulu-Natal, Durban 4001, South Africa
Nicolette Van Der Walt
Emergency & Clinical Services Support, Western Cape Department of Health and Wellness, Cape Town 8000, South Africa
Juanita O. Arendse
Division of Health Systems and Public Health, Department of Global Health, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa
Nicole Wolter
Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
Sibongile Walaza
Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
Waasila Jassat
Health Practice, Genesis Analytics, Johannesburg 2196, South Africa
Anne von Gottberg
Centre for Respiratory Diseases and Meningitis, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
Patrick L. Hannan
Division of Epidemiology and Biostatistics, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
Daniel R. Feikin
Department of Immunizations, Vaccines, and Biologicals, World Health Organization, CH-1211 Geneva, Switzerland
Keith Cloete
Western Cape Department of Health and Wellness, Cape Town 8000, South Africa
Andrew Boulle
Centre for Infectious Disease Epidemiology and Research, School of Public Health, Faculty of Health Sciences, University of Cape Town, Cape Town 7925, South Africa
There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced widespread SARS-CoV-2 infection before vaccine availability. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa, in an observational cohort study of >2 million adults during 2020–2022. We described SARS-CoV-2 testing, COVID-19 outcomes, and vaccine uptake over time. We used multivariable cox models to estimate the association of BNT162b2 and Ad26.COV2.S vaccination with COVID-19-related hospitalization and death, adjusting for demographic characteristics, underlying health conditions, socioeconomic status proxies, and healthcare utilization. We found that by the end of 2022, 41% of surviving adults had completed vaccination and 8% had received a booster dose. Recent vaccination was associated with notable reductions in severe COVID-19 during periods dominated by Delta, and Omicron BA.1/2 and BA.4/5 (sub)lineages. During the latest Omicron BA.4/5 wave, within 3 months of vaccination or boosting, BNT162b2 and Ad26.COV2.S were each 84% effective against death (95% CIs: 57–94 and 49–95, respectively). However, distinct reductions of effectiveness occurred at longer times post completing or boosting vaccination. Results highlight the importance of continued emphasis on COVID-19 vaccination and boosting for those at high risk of severe COVID-19, even in settings with widespread infection-induced immunity.
