Efficacy of the AstraZeneca coronavirus vaccine against the B.1.351 South African Variant

Africa, Astrazeneca, B.1.351, Coronavirus, England, Europe, Health, Infection, K417N, Science, South Africa, Testing, Treatment, UK, Vaccine, Variants

Study conclusions:  A two-dose regimen of the ChAdOx1 nCoV-19 [AstraZeneca] vaccine did not show protection against mild-to-moderate Covid-19 due to the B.1.351 [South Africa ] variant.

“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.”

Full paper on NEJM


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** This post was originally published on March 19, 2021 **