Efficacy of primary series AZD1222 (ChAdOx1 nCoV-19) vaccination against SARS-CoV-2 variants of concern: Final analysis of a randomized, placebo-controlled, phase 1b/2 study in South African adults (COV005)

Journal article

COVID-19 vaccine efficacy (VE) has been observed to vary against antigenically distinct SARS-CoV-2 variants of concern (VoC). Here we report the final analysis of VE and safety from COV005: a phase 1b/2, multicenter, double-blind, randomized, placebo-controlled study of primary series AZD1222 (ChAdOx1 nCoV-19) vaccination in South African adults aged 18-65 years. South Africa's first, second, and third waves of SARS-CoV-2 infections were respectively driven by the ancestral SARS-CoV-2 virus (wild type, WT), and SARS-CoV-2 Beta and Delta VoCs. VE against asymptomatic and symptomatic infection was 90.6% for WT, 6.7% for Beta and 77.1% for Delta. No cases of severe COVID-19 were documented ahead of unblinding. Safety was consistent with the interim analysis, with no new safety concerns identified. Notably, South Africa's Delta wave occurred ≥ 9 months after primary series vaccination, suggesting that primary series AZD1222 vaccination offers a good durability of protection, potentially due to an anamnestic response.

Clinical trial identifier: CT.gov NCT04444674.

Authors: Koen, AL; Izu, A; Baillie, V; Kwatra, G; Cutland, CL

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Elsevier
• Journal: Vaccine
• Volume: 41
• Issue: 23
• Pages: 3486-3492
• Place of publication: Netherlands
• Publication date: 2023-04-27
• Acceptance date: 2023-04-21
• DOI: 10.1016/j.vaccine.2023.04.058
• EISSN: 1873-2518
• ISSN: 0264-410X
• Pmid: 37149443
• Language: English
• Keywords: South Africa; COVID-19 vaccines; ChAdOx1 nCoV-19; vaccination; COVID-19; SARS-CoV-2