Safety and efficacy of the ChAdOx1 nCoV-19 (AZD1222) Covid-19 vaccine against the B.1.351 variant in South Africa
Open accessPreprint — published as 10.1056/nejmoa2102214 · Paper page
Abstract
Background: Assessing safety and efficacy of Covid-19 vaccines in different populations is essential, as is investigation of efficacy against emerging SARS-CoV-2 variants of concern including the B.1.351 (501Y.V2) variant first identified in South Africa. Methods: We conducted a randomized multicentre, double blinded controlled trial on safety and efficacy of ChAdOx1-nCoV19 in HIV-uninfected people in South Africa. Participants age 18 to <65 years randomized (1:1) to two doses of vaccine containing 5×10 10 viral particles or placebo (0.9%NaCl) 21-35 days apart. Post 2 nd -dose serum samples (n=25) were tested by pseudotyped (PSVNA) and live virus (LVNA) neutralization assays against the D614G and B.1.351 variants. Primary endpoints were safety and vaccine efficacy (VE) >14 days following second dose against laboratory confirmed symptomatic Covid-19. Results: 2026 HIV-uninfected adults were enrolled between June 24 th and Nov 9 th , 2020; 1010 and 1011 received at least one dose of placebo or vaccine, respectively. Median age was 31 years. The B.1.351 variant showed increased resistance to vaccinee sera using the PSVNA and LVNA. In the primary endpoint analysis, 23/717 (3.2%) placebo and 19/750 (2.5%) vaccine recipients developed mild-moderate Covid-19; VE 21.9% (95%Confidence Interval: −49.9; 59.8). Of the primary endpoint cases, 39/42 (92.9%) were the B.1.351 variant; against which VE was 10.4% (95%CI: −76.8; 54.8) analyzed as a secondary objective. The incidence of serious adverse events was balanced between the vaccine and placebo groups. Conclusions: A two-dose regimen of ChAdOx1-nCoV19 did not show protection against mild-moderate Covid-19 due to B.1.351 variant, however, VE against severe Covid-19 is undetermined. (Funded by The Bill & Melinda Gates Foundation and South African Medical Research Council; ClinicalTrails.gov number, NCT04444674 ).
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Preliminary data suggest that, in common with other ancestral spike-based vaccines, ChAdOx1 nCov-19 might have a lower clinical efficacy against upper respiratory infection caused by viral lineages bearing the E484K mutation.
“Preliminary data suggest that, in common with other ancestral spike-based vaccines, ChAdOx1 nCov-19 might have a lower clinical efficacy against upper respiratory infection caused by viral lineages bearing this mutation.49”
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- Authors
- Madhi, S. A., Baillie, V., Cutland, C. L., Voysey, M., Koen, A. L., Fairlie, L., Padayachee, S. D., Dheda, K., Barnabas, S. L., Bhorat, Q. E., Briner, C., Kwatra, G., NGS-SA, Wits-VIDA COVID team, Ahmed, K., Aley, P., Bhikha, S., Bhiman, J. N., Bhorat, A. E., Plessis, J. D., Esmail, A., Groenewald, M., Horne, E., Hwa, S.-H., Jose, A., Lambe, T., Laubscher, M., Malahleha, M., Masenya, M., Masilela, M., McKenzie, S., Molapo, K., Moultrie, A., Oelofse, S., Patel, F., Pillay, S., Rhead, S., Rodel, H., Rossouw, L., Taoushanis, C., Tegally, H., Thombrayil, A., Eck, S. V., Wibmer, C. K., Durham, N. M., Kelly, E. J., Villafana, T. L., Gilbert, S., Pollard, A. J., de Oliveira, T., Moore, P. L., Sigal, A., & Izu, A.
- Affiliations
- South African Medical Research Council (ZA)
- University of the Witwatersrand (ZA)
- University of Oxford (GB)
- Setshaba Research Centre (ZA)
- University of Cape Town (ZA)
- Stellenbosch University (ZA)
- Soweto CTC (ZA)
- National Health Laboratory Service (ZA)
- Africa Health Research Institute (ZA)
- Max Planck Institute for Infection Biology (DE)
- AstraZeneca (United Kingdom) (GB)
- Corresponding author
- Madhi, Shabir A.
- ORCID
- Madhi, Shabir A.
- Baillie, Vicky
- Cutland, Clare L.
- Voysey, Merryn
- Koen, Anthonet L.
- Fairlie, Lee
- Dheda, Keertan
- Barnabas, Shaun L.
- Bhorat, Qasim Ebrahim
- Briner, Carmen
- Kwatra, Gaurav
- Ahmed, Khatija
- Aley, Parvinder
- Bhiman, Jinal N.
- Bhorat, As’ad Ebrahim
- Esmail, Aliasgar
- Horne, Elizea
- Hwa, Shi-Hsia
- Lambe, Teresa
- Laubscher, Matt
- Malahleha, Mookho
- Masenya, Masebole
- Moultrie, Andrew
- Oelofse, Suzette
- Patel, Faeezah
- Pillay, Sureshnee
- Rhead, Sarah
- Rodel, Hylton
- Taoushanis, Carol
- Tegally, Houriiyah
- Wibmer, Constantinos Kurt
- Durham, Nicholas M.
- Kelly, Elizabeth J
- Villafana, Tonya L
- Gilbert, Sarah
- Pollard, Andrew J
- de Oliveira, Tulio
- Moore, Penny L.
- Sigal, Alex
- Izu, Alane
- Venue
- New England Journal of Medicine
- Publisher
- openRxiv
- Published
- 2021-02-12
- Volume
- 384
- Issue
- 20
- Pages
- 1885-1898
- ISSN
- 0028-4793 (ISSN-L)
- PMC
- PMC7993410
- OpenAlex
- W3139533040
- Cited by
- 1,257
- References
- 6
- Citations by year
- 2026: 9 · 2025: 33 · 2024: 64 · 2023: 135 · 2022: 413 · 2021: 600 · 2020: 2
- FWCI
- 96.76
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- cc-by
- Locations
- New England Journal of Medicine (publishedVersion, cc-by)
- medRxiv (acceptedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- LSHTM Research Online (London School of Hygiene and Tropical Medicine) (acceptedVersion)
- Funders
- Bill and Melinda Gates Foundation (INV-017710, INV-018944)
- AstraZeneca
- Massachusetts Medical Society
- UK Research and Innovation (MC_PC_19055)
- National Institute for Health and Care Research (COV19OxfordVaccine01, MC_PC_19055)
- Department of Health and Social Care
- University of Oxford
- National Research Foundation (98341)
- South African Medical Research Council (RFA-EMU-02-2017, TMA-2015SF-1043, 96167, 98341, TMA-1051-TESAII)
- University of Cape Town
- National Institutes of Health (98341, RFA-EMU-02-2017)
- Medical Research Council
- Fogarty International Center (R21TW011454)
- European and Developing Countries Clinical Trials Partnership (TMA 2015 SF - 1043, TMA‐1051‐TESAII, TMA 2015 CDF - 1052)
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Social Sciences › Health › Vaccine Coverage and Hesitancy
- Keywords
- ChAdOx1 nCoV-19 vaccine, COVID-19 vaccine efficacy, B.1.351 variant, SARS-CoV-2 variants of concern, neutralizing antibodies, pseudovirus neutralization, symptomatic COVID-19, vaccine safety, adenovirus vector vaccine
- MeSH terms
- Immunogenicity, Vaccine, COVID-19, SARS-CoV-2, COVID-19 Vaccines, COVID-19 Serological Testing, ChAdOx1 nCoV-19, Adenoviridae, Adolescent, Adult, Double-Blind Method, Humans, Middle Aged, South Africa, T-Lymphocytes, Treatment Failure, Young Adult, Antibodies, Neutralizing, Vaccine Potency
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