Shabir A. Madhi , Ph.D., Vicky Baillie , Ph.D., Clare L. Cutland , Ph.D., Merryn Voysey , D.Phil., Anthonet L. Koen , M.B., B.Ch., Lee Fairlie , F.C.Paeds., Sherman D. Padayachee , M.B., Ch.B., Keertan Dheda , Ph.D., Shaun L. Barnabas , Ph.D., Qasim E. Bhorat , M.Sc., Carmen Briner , M.B., B.Ch., Gaurav Kwatra , Ph.D., Khatija Ahmed , F.C.Path. (Micro), Parvinder Aley , D.Phil., Sutika Bhikha , M.B., B.Ch., Jinal N. Bhiman , Ph.D., As’ad E. Bhorat , F.R.A.C.G.P., Jeanine du Plessis , B.Sc., Aliasgar Esmail , M.D., Marisa Groenewald , M.B., B.Ch., Elizea Horne , M.B., B.Ch., Shi-Hsia Hwa , M.Sc., Aylin Jose , M.B., B.Ch., Teresa Lambe , Ph.D., Matt Laubscher , M.Sc., Mookho Malahleha , M.B., Ch.B., Masebole Masenya , M.B., Ch.B., Mduduzi Masilela , M.B., Ch.B., Shakeel McKenzie , B.Sc., Kgaogelo Molapo , Nat.Dip.O.H.S., Andrew Moultrie , B.Sc., Suzette Oelofse , M.B., Ch.B., Faeezah Patel , M.B., B.Ch., Sureshnee Pillay , B.Sc., Sarah Rhead , M.B., Ch.B., Hylton Rodel , B.Sc., Lindie Rossouw , M.B., B.Ch., Carol Taoushanis , B.Pharm., Houriiyah Tegally , M.Sc., Asha Thombrayil , M.B., B.Ch., Samuel van Eck , R.N., Constantinos K. Wibmer , Ph.D., Nicholas M. Durham , Ph.D., Elizabeth J. Kelly , Ph.D., Tonya L. Villafana , Ph.D., Sarah Gilbert , Ph.D., Andrew J. Pollard , F.Med.Sci., Tulio de Oliveira , Ph.D., Penny L. Moore , Ph.D., Alex Sigal , Ph.D., Alane Izu , Ph.D. *
16 March 2021
Keyword part (code): 18Keyword part (keyword): Infectious DiseaseKeyword part (code): 18_2Keyword part (keyword): VaccinesKeyword part (code): 18_6Keyword part (keyword): Viral Infections , 18, Infectious Disease, Keyword part (code): 18_2Keyword part (keyword): VaccinesKeyword part (code): 18_6Keyword part (keyword): Viral Infections , 18_2, Vaccines, 18_6, Viral Infections
Assessment of the safety and efficacy of vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in different populations is essential, as is investigation of the efficacy of the vaccines against emerging SARS-CoV-2 variants of concern, including the B.1.351 (501Y.V2) variant first identified in South Africa.
We conducted a multicenter, double-blind, randomized, controlled trial to assess the safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) in people not infected with the human immunodeficiency virus (HIV) in South Africa. Participants 18 to less than 65 years of age were assigned in a 1:1 ratio to receive two doses of vaccine containing 5×10 10 viral particles or placebo (0.9% sodium chloride solution) 21 to 35 days apart. Serum samples obtained from 25 participants after the second dose were tested by pseudovirus and live-virus neutralization assays against the original D614G virus and the B.1.351 variant. The primary end points were safety and efficacy of the vaccine against laboratory-confirmed symptomatic coronavirus 2019 illness (Covid-19) more than 14 days after the second dose.
Between June 24 and November 9, 2020, we enrolled 2026 HIV-negative adults (median age, 30 years); 1010 and 1011 participants received at least one dose of placebo or vaccine, respectively. Both the pseudovirus and the live-virus neutralization assays showed greater resistance to the B.1.351 variant in serum samples obtained from vaccine recipients than in samples from placebo recipients. In the primary end-point analysis, mild-to-moderate Covid-19 developed in 23 of 717 placebo recipients (3.2%) and in 19 of 750 vaccine recipients (2.5%), for an efficacy of 21.9% (95% confidence interval [CI], −49.9 to 59.8). Among the 42 participants with Covid-19, 39 cases (92.9%) were caused by the B.1.351 variant; vaccine efficacy against this variant, analyzed as a secondary end point, was 10.4% (95% CI, −76.8 to 54.8). The incidence of serious adverse events was balanced between the vaccine and placebo groups.
A two-dose regimen of the ChAdOx1 nCoV-19 vaccine did not show protection against mild-to-moderate Covid-19 due to the B.1.351 variant. (Funded by the Bill and Melinda Gates Foundation and others; ClinicalTrials.gov number, NCT04444674; Pan African Clinical Trials Registry number, PACTR202006922165132).