Phase 3 Safety and Efficacy of AZD1222 (ChAdOx1 nCoV-19) Covid-19 Vaccine.
New England Journal of Medicine
BACKGROUND: The safety and efficacy of the AZD1222 (ChAdOx1 nCoV-19) vaccine in a large, diverse population at increased risk for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States, Chile, and Peru has not been known.
METHODS: In this ongoing, double-blind, randomized, placebo-controlled, phase 3 clinical trial, we investigated the safety, vaccine efficacy, and immunogenicity of two doses of AZD1222 as compared with placebo in preventing the onset of symptomatic and severe coronavirus disease 2019 (Covid-19) 15 days or more after the second dose in adults, including older adults, in the United States, Chile, and Peru.
RESULTS: A total of 32,451 participants underwent randomization, in a 2:1 ratio, to receive AZD1222 (21,635 participants) or placebo (10,816 participants). AZD1222 was safe, with low incidences of serious and medically attended adverse events and adverse events of special interest; the incidences were similar to those observed in the placebo group. Solicited local and systemic reactions were generally mild or moderate in both groups. Overall estimated vaccine efficacy was 74.0% (95% confidence interval [CI], 65.3 to 80.5; P
CONCLUSIONS: AZD1222 was safe and efficacious in preventing symptomatic and severe Covid-19 across diverse populations that included older adults. (Funded by AstraZeneca and others; ClinicalTrials.gov number, NCT04516746.).
Falsey AR, Sobieszczyk ME, Hirsch I, Sproule S, Robb ML, Corey L, Neuzil KM, Hahn W, Hunt J, Mulligan MJ, McEvoy C, DeJesus E, Hassman M, Little SJ, Pahud BA, Durbin A, Pickrell P, Daar ES, Bush L, Solis J, Carr QO, Oyedele T, Buchbinder S, Cowden J, Vargas SL, Guerreros Benavides A, Call R, Keefer MC, Kirkpatrick BD, Pullman J, Tong T, Brewinski Isaacs M, Benkeser D, Janes HE, Nason MC, Green JA, Kelly EJ, Maaske J, Mueller N, Shoemaker K, Takas T, Marshall RP, Pangalos MN, Villafana T, Gonzalez-Lopez A; AstraZeneca AZD1222 Clinical Study Group. Phase 3 Safety and Efficacy of AZD1222 (ChAdOx1 nCoV-19) Covid-19 Vaccine. N Engl J Med. 2021 Dec 16;385(25):2348-2360. doi: 10.1056/NEJMoa2105290. Epub 2021 Sep 29. PMID: 34587382; PMCID: PMC8522798.