Early data from a University of Oxford study indicates the COVID-19 vaccine it jointly developed with AstraZeneca is effective against the P.1 variant, which originated in Brazil.
The study has not yet been published, but Reuters confirmed its results.
South Africa recently paused the vaccine rollout, where a similar variant is circulating after early study data indicated the vaccine offers little to no protection against mild-to-moderate disease.
That study found that the AstraZeneca ChAdOx1 nCoV-19 had an efficacy of 21.9% after 14 days of receiving the second dose of vaccine. The participants in that study were seronegative to the adenovirus used as a vector.
The P.1 variant appears to resist immunity from natural infection, and a Lancet preprint suggested that the COVID-19 vaccine from China-based CoronaVac is not effective against the variant.
Brazil has seen one of the longest-lived waves of COVID-19 infections, with more than 75,000 new cases announced there on March 4 — the highest yet for the country.
The AstraZeneca vaccine will likely be the fourth vaccine to be granted emergency use authorization in the U.S.