@article{Kassanjee2024,
abstract = {Background There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced high levels of SARS-CoV-2 infection in a mostly vaccine-na{\"{i}}ve population, and has limited vaccine coverage and competing health service priorities. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa. Methods We performed an observational cohort study of {\textgreater}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 hospitalisation and death, adjusting for demographic characteristics, underlying health conditions, socioeconomic status proxies and healthcare utilisation. Results By end 2022, only 41{\%} of surviving adults had completed vaccination and 8{\%} a booster dose, despite several waves of severe COVID-19. Recent vaccination was associated with notable reductions in severe COVID-19 during distinct analysis periods dominated by Delta, Omicron BA.1/2 and BA.4/5 (sub)lineages: within 6 months of completing vaccination or boosting, vaccine effectiveness was 46-92{\%} for death (range across periods), 45-92{\%} for admission with severe disease or death, and 25-90{\%} for any admission or death. During the 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, there were distinct reductions of VE at larger times post completing or boosting vaccination. Conclusions Continued emphasis on regular COVID-19 vaccination including boosting is important for those at high risk of severe COVID-19 even in settings with widespread infection-induced immunity. {\#}{\#}{\#} Competing Interest Statement MD reports grants from Viiv Healthcare, outside the submitted work. CC reports grants from Sanofi Pasteur, US Centers for Disease Control and Prevention (CDC), Wellcome Trust, South African Medical Research Council (SAMRC) and the Bill {\&} Melinda Gates Foundation. NW reports grants from the Bill and Melinda Gates Foundation and Sanofi. SW reports grants from US CDC and Bill and Melinda Gates Foundation. AvG reports grants from the World Health Organisation Regional Office for Africa (WHO-AFRO), US CDC, SAMRC, Fleming Fund, Africa Centres for Disease Control / African Society for Laboratory Medicine. AB reports grants from the US National Institutes for Health, Bill and Melinda Gates Foundation and the Wellcome Trust. {\#}{\#}{\#} Funding Statement This work was supported by funding from the Western Cape Government Department of Health and Wellness for the Western Cape Provincial Health Data Centre, the US National Institutes for Health [R01 HD080465, U01 AI069924], the Bill and Melinda Gates Foundation [1164272, 1191327], the United States Agency for International Development [72067418CA00023], the European Union [101045989], the Grand Challenges ICODA pilot initiative delivered by Health Data Research UK and funded by the Bill {\&} Melinda Gates and Minderoo Foundations [INV-017293], and the Wellcome Trust [203135/Z/16/Z, 222574]. The funders had no role in the study design, data collection, data analysis, data interpretation, or writing of this report. The opinions, findings and conclusions expressed in this manuscript reflect those of the authors alone. {\#}{\#}{\#} Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Health Research Ethics Committee of the University of Cape Town gave ethical approval for this work (HREC REF 460/2020). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data are not publicly available due to privacy or ethical restrictions. The data that support the findings of this study can be requested from the Western Cape Provincial Health Data Centre (WCPHDC) [{\textless}https://www.westerncape.gov.za/general-publication/provincial-health-data-centre{\textgreater}]; restrictions apply to the availability of these data.},
author = {Kassanjee, Reshma and Davies, Mary-Ann and Heekes, Alexa and Mahomed, Hassan and Hawkridge, Anthony J and Wolmarans, Milani and Morden, Erna and Jacobs, Theuns and Cohen, Cheryl and Moultrie, Harry and Lessells, Richard J and Walt, Nicolette Van Der and Arendse, Juanita O and Goeiman, Hilary and Mudaly, Vanessa and Wolter, Nicole and Walaza, Sibongile and Jassat, Waasila and von Gottberg, Anne and Hannan, Patrick L and Rousseau, Petro and Feikin, Daniel and Cloete, Keith and Boulle, Andrew},
doi = {10.1101/2024.01.24.24301721},
file = {:C$\backslash$:/Users/01462563/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Kassanjee et al. - 2024 - COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa.pdf:pdf},
journal = {medRxiv},
keywords = {OA,fund{\_}ack,genomics{\_}fund{\_}ack,original},
mendeley-tags = {OA,fund{\_}ack,genomics{\_}fund{\_}ack,original},
month = {jan},
pages = {2024.01.24.24301721},
publisher = {Cold Spring Harbor Laboratory Press},
title = {{COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa: an observational cohort study during 2020-2022}},
url = {https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1 https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1.abstract},
volume = {15},
year = {2024}
}

{"_id":"WDhqgNgwfMFCabLnx","bibbaseid":"kassanjee-davies-heekes-mahomed-hawkridge-wolmarans-morden-jacobs-etal-covid19vaccineuptakeandeffectivenessbytimesincevaccinationinthewesterncapeprovincesouthafricaanobservationalcohortstudyduring20202022-2024","author_short":["Kassanjee, R.","Davies, M.","Heekes, A.","Mahomed, H.","Hawkridge, A. J","Wolmarans, M.","Morden, E.","Jacobs, T.","Cohen, C.","Moultrie, H.","Lessells, R. J","Walt, N. V. D.","Arendse, J. O","Goeiman, H.","Mudaly, V.","Wolter, N.","Walaza, S.","Jassat, W.","von Gottberg, A.","Hannan, P. L","Rousseau, P.","Feikin, D.","Cloete, K.","Boulle, A."],"bibdata":{"bibtype":"article","type":"article","abstract":"Background There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced high levels of SARS-CoV-2 infection in a mostly vaccine-naïve population, and has limited vaccine coverage and competing health service priorities. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa. Methods We performed an observational cohort study of \\textgreater2 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 hospitalisation and death, adjusting for demographic characteristics, underlying health conditions, socioeconomic status proxies and healthcare utilisation. Results By end 2022, only 41% of surviving adults had completed vaccination and 8% a booster dose, despite several waves of severe COVID-19. Recent vaccination was associated with notable reductions in severe COVID-19 during distinct analysis periods dominated by Delta, Omicron BA.1/2 and BA.4/5 (sub)lineages: within 6 months of completing vaccination or boosting, vaccine effectiveness was 46-92% for death (range across periods), 45-92% for admission with severe disease or death, and 25-90% for any admission or death. During the 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, there were distinct reductions of VE at larger times post completing or boosting vaccination. Conclusions Continued emphasis on regular COVID-19 vaccination including boosting is important for those at high risk of severe COVID-19 even in settings with widespread infection-induced immunity. ### Competing Interest Statement MD reports grants from Viiv Healthcare, outside the submitted work. CC reports grants from Sanofi Pasteur, US Centers for Disease Control and Prevention (CDC), Wellcome Trust, South African Medical Research Council (SAMRC) and the Bill & Melinda Gates Foundation. NW reports grants from the Bill and Melinda Gates Foundation and Sanofi. SW reports grants from US CDC and Bill and Melinda Gates Foundation. AvG reports grants from the World Health Organisation Regional Office for Africa (WHO-AFRO), US CDC, SAMRC, Fleming Fund, Africa Centres for Disease Control / African Society for Laboratory Medicine. AB reports grants from the US National Institutes for Health, Bill and Melinda Gates Foundation and the Wellcome Trust. ### Funding Statement This work was supported by funding from the Western Cape Government Department of Health and Wellness for the Western Cape Provincial Health Data Centre, the US National Institutes for Health [R01 HD080465, U01 AI069924], the Bill and Melinda Gates Foundation [1164272, 1191327], the United States Agency for International Development [72067418CA00023], the European Union [101045989], the Grand Challenges ICODA pilot initiative delivered by Health Data Research UK and funded by the Bill & Melinda Gates and Minderoo Foundations [INV-017293], and the Wellcome Trust [203135/Z/16/Z, 222574]. The funders had no role in the study design, data collection, data analysis, data interpretation, or writing of this report. The opinions, findings and conclusions expressed in this manuscript reflect those of the authors alone. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Health Research Ethics Committee of the University of Cape Town gave ethical approval for this work (HREC REF 460/2020). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data are not publicly available due to privacy or ethical restrictions. The data that support the findings of this study can be requested from the Western Cape Provincial Health Data Centre (WCPHDC) [\\textlesshttps://www.westerncape.gov.za/general-publication/provincial-health-data-centre\\textgreater]; restrictions apply to the availability of these data.","author":[{"propositions":[],"lastnames":["Kassanjee"],"firstnames":["Reshma"],"suffixes":[]},{"propositions":[],"lastnames":["Davies"],"firstnames":["Mary-Ann"],"suffixes":[]},{"propositions":[],"lastnames":["Heekes"],"firstnames":["Alexa"],"suffixes":[]},{"propositions":[],"lastnames":["Mahomed"],"firstnames":["Hassan"],"suffixes":[]},{"propositions":[],"lastnames":["Hawkridge"],"firstnames":["Anthony","J"],"suffixes":[]},{"propositions":[],"lastnames":["Wolmarans"],"firstnames":["Milani"],"suffixes":[]},{"propositions":[],"lastnames":["Morden"],"firstnames":["Erna"],"suffixes":[]},{"propositions":[],"lastnames":["Jacobs"],"firstnames":["Theuns"],"suffixes":[]},{"propositions":[],"lastnames":["Cohen"],"firstnames":["Cheryl"],"suffixes":[]},{"propositions":[],"lastnames":["Moultrie"],"firstnames":["Harry"],"suffixes":[]},{"propositions":[],"lastnames":["Lessells"],"firstnames":["Richard","J"],"suffixes":[]},{"propositions":[],"lastnames":["Walt"],"firstnames":["Nicolette","Van","Der"],"suffixes":[]},{"propositions":[],"lastnames":["Arendse"],"firstnames":["Juanita","O"],"suffixes":[]},{"propositions":[],"lastnames":["Goeiman"],"firstnames":["Hilary"],"suffixes":[]},{"propositions":[],"lastnames":["Mudaly"],"firstnames":["Vanessa"],"suffixes":[]},{"propositions":[],"lastnames":["Wolter"],"firstnames":["Nicole"],"suffixes":[]},{"propositions":[],"lastnames":["Walaza"],"firstnames":["Sibongile"],"suffixes":[]},{"propositions":[],"lastnames":["Jassat"],"firstnames":["Waasila"],"suffixes":[]},{"propositions":["von"],"lastnames":["Gottberg"],"firstnames":["Anne"],"suffixes":[]},{"propositions":[],"lastnames":["Hannan"],"firstnames":["Patrick","L"],"suffixes":[]},{"propositions":[],"lastnames":["Rousseau"],"firstnames":["Petro"],"suffixes":[]},{"propositions":[],"lastnames":["Feikin"],"firstnames":["Daniel"],"suffixes":[]},{"propositions":[],"lastnames":["Cloete"],"firstnames":["Keith"],"suffixes":[]},{"propositions":[],"lastnames":["Boulle"],"firstnames":["Andrew"],"suffixes":[]}],"doi":"10.1101/2024.01.24.24301721","file":":C$\\$:/Users/01462563/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Kassanjee et al. - 2024 - COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa.pdf:pdf","journal":"medRxiv","keywords":"OA,fund_ack,genomics_fund_ack,original","mendeley-tags":"OA,fund_ack,genomics_fund_ack,original","month":"jan","pages":"2024.01.24.24301721","publisher":"Cold Spring Harbor Laboratory Press","title":"COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa: an observational cohort study during 2020-2022","url":"https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1 https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1.abstract","volume":"15","year":"2024","bibtex":"@article{Kassanjee2024,\r\nabstract = {Background There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced high levels of SARS-CoV-2 infection in a mostly vaccine-na{\\\"{i}}ve population, and has limited vaccine coverage and competing health service priorities. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa. Methods We performed an observational cohort study of {\\textgreater}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 hospitalisation and death, adjusting for demographic characteristics, underlying health conditions, socioeconomic status proxies and healthcare utilisation. Results By end 2022, only 41{\\%} of surviving adults had completed vaccination and 8{\\%} a booster dose, despite several waves of severe COVID-19. Recent vaccination was associated with notable reductions in severe COVID-19 during distinct analysis periods dominated by Delta, Omicron BA.1/2 and BA.4/5 (sub)lineages: within 6 months of completing vaccination or boosting, vaccine effectiveness was 46-92{\\%} for death (range across periods), 45-92{\\%} for admission with severe disease or death, and 25-90{\\%} for any admission or death. During the 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, there were distinct reductions of VE at larger times post completing or boosting vaccination. Conclusions Continued emphasis on regular COVID-19 vaccination including boosting is important for those at high risk of severe COVID-19 even in settings with widespread infection-induced immunity. {\\#}{\\#}{\\#} Competing Interest Statement MD reports grants from Viiv Healthcare, outside the submitted work. CC reports grants from Sanofi Pasteur, US Centers for Disease Control and Prevention (CDC), Wellcome Trust, South African Medical Research Council (SAMRC) and the Bill {\\&} Melinda Gates Foundation. NW reports grants from the Bill and Melinda Gates Foundation and Sanofi. SW reports grants from US CDC and Bill and Melinda Gates Foundation. AvG reports grants from the World Health Organisation Regional Office for Africa (WHO-AFRO), US CDC, SAMRC, Fleming Fund, Africa Centres for Disease Control / African Society for Laboratory Medicine. AB reports grants from the US National Institutes for Health, Bill and Melinda Gates Foundation and the Wellcome Trust. {\\#}{\\#}{\\#} Funding Statement This work was supported by funding from the Western Cape Government Department of Health and Wellness for the Western Cape Provincial Health Data Centre, the US National Institutes for Health [R01 HD080465, U01 AI069924], the Bill and Melinda Gates Foundation [1164272, 1191327], the United States Agency for International Development [72067418CA00023], the European Union [101045989], the Grand Challenges ICODA pilot initiative delivered by Health Data Research UK and funded by the Bill {\\&} Melinda Gates and Minderoo Foundations [INV-017293], and the Wellcome Trust [203135/Z/16/Z, 222574]. The funders had no role in the study design, data collection, data analysis, data interpretation, or writing of this report. The opinions, findings and conclusions expressed in this manuscript reflect those of the authors alone. {\\#}{\\#}{\\#} Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Health Research Ethics Committee of the University of Cape Town gave ethical approval for this work (HREC REF 460/2020). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data are not publicly available due to privacy or ethical restrictions. The data that support the findings of this study can be requested from the Western Cape Provincial Health Data Centre (WCPHDC) [{\\textless}https://www.westerncape.gov.za/general-publication/provincial-health-data-centre{\\textgreater}]; restrictions apply to the availability of these data.},\r\nauthor = {Kassanjee, Reshma and Davies, Mary-Ann and Heekes, Alexa and Mahomed, Hassan and Hawkridge, Anthony J and Wolmarans, Milani and Morden, Erna and Jacobs, Theuns and Cohen, Cheryl and Moultrie, Harry and Lessells, Richard J and Walt, Nicolette Van Der and Arendse, Juanita O and Goeiman, Hilary and Mudaly, Vanessa and Wolter, Nicole and Walaza, Sibongile and Jassat, Waasila and von Gottberg, Anne and Hannan, Patrick L and Rousseau, Petro and Feikin, Daniel and Cloete, Keith and Boulle, Andrew},\r\ndoi = {10.1101/2024.01.24.24301721},\r\nfile = {:C$\\backslash$:/Users/01462563/AppData/Local/Mendeley Ltd./Mendeley Desktop/Downloaded/Kassanjee et al. - 2024 - COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa.pdf:pdf},\r\njournal = {medRxiv},\r\nkeywords = {OA,fund{\\_}ack,genomics{\\_}fund{\\_}ack,original},\r\nmendeley-tags = {OA,fund{\\_}ack,genomics{\\_}fund{\\_}ack,original},\r\nmonth = {jan},\r\npages = {2024.01.24.24301721},\r\npublisher = {Cold Spring Harbor Laboratory Press},\r\ntitle = {{COVID-19 vaccine uptake and effectiveness by time since vaccination in the Western Cape province, South Africa: an observational cohort study during 2020-2022}},\r\nurl = {https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1 https://www.medrxiv.org/content/10.1101/2024.01.24.24301721v1.abstract},\r\nvolume = {15},\r\nyear = {2024}\r\n}\r\n","author_short":["Kassanjee, R.","Davies, M.","Heekes, A.","Mahomed, H.","Hawkridge, A. 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