AstraZeneca vaccine doesn’t prevent B1351 COVID in early trial

Two doses of the AstraZeneca-Oxford University COVID-19 vaccine were ineffective against mild-to-moderate infections with the B1351 variant first identified in South Africa, according to a phase 1b-2 clinical trial published today in the New England Journal of Medicine.

The double-blind multicenter study, led by scientists at the South African Medical Research Council Vaccines and Infectious Diseases Analytics Research Unit, studied the safety and the efficacy of the AstraZeneca ChAdOx1 nCoV-19 vaccine in HIV-negative adults aged 18 to 64 who received either two standard doses of the vaccine or a placebo in a 1:1 ratio 21 to 35 days apart from Jun 24 to Nov 9, 2020. Median follow-up after the second dose was 121 days.

10.4% effectiveness against variant

Of the 750 participants vaccine recipients, 19 (2.5%) developed mild to moderate COVID-19 more than 14 days after the second dose, compared with 23 of 717 placebo recipients (3.2%).  The incidence of COVID-19 among the vaccine group was 731 per 1,000 person-years, compared with 93.6 per 1,000 person-years among the placebo group, for an efficacy of 21.9% (95% confidence interval [CI], -49.9 to 59.8).

Of the 42 total cases of COVID-19, 39 (92.9%) were caused by B1351, for a vaccine effectiveness against this variant of 10.4% (95% CI, -76.8 to 54.8). All 42 cases were mild to moderate, and no patients were hospitalized.


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