How Well Does the Oxford/AstraZeneca Vaccine Stand Up Against the South African SARS-CoV-2 Variant?

The emergence of SARS-CoV-2 variants has raised concerns about vaccine efficacy. The B.1.351 (South African) variant, which contains mutations in the receptor-binding and N-terminal domains, appears less likely to be neutralized by naturally occurring and monoclonal antibodies. In this phase 1b–2 placebo-controlled trial in South Africa, investigators assessed the efficacy of the Oxford/AstraZeneca adenovirus-vectored vaccine, AZD1222, in preventing PCR-confirmed symptomatic COVID-19 at least 14 days after the second dose of vaccine. A total of 2026 HIV-negative participants (median age, 30; 70% Black African; 19% with body-mass index of 30.0–39.9) were randomized 1:1 to receive vaccine (two doses 21–35 days apart) or placebo.

Among 1467 pre…