Pfizer-BioNTechs coronavirus vaccine appears to be highly effective against a more contagious variant of the virus first discovered in Brazil, according to a new lab study published Monday in the New England Journal of Medicine.
The study, conducted by Pfizer scientists and researchers at the University of Texas Medical Branch, used blood samples from vaccinated individuals against an engineered version of the variant. The samples were taken from participants in Pfizers late-stage clinical trials for the vaccine and were obtained between two to four weeks after they received the second dose.
In the lab, the ability of the vaccine to neutralize the variant, known as P.1., was roughly equivalent to its impact on the original strain of the virus, the researchers said. According to Pfizer, its vaccine had a 95 percent efficacy rate against the less contagious coronavirus strain in trials last year.
The P.1 variant was first detected in January and has since spread from its origins in the Amazonian city of Manaus to multiple countries, including the United States.
An earlier study by researchers in Britain and Sao Paulo, which had not yet been peer-reviewed, suggested that P.1 was more contagious and better equipped to evade immune protection than previous versions of the virus.
A separate study also by researchers in Sao Paulo and Washington Universitys School of Medicine said that the vaccine developed by Chinese drugmaker Sinovac appeared to be ineffective against P.1.
The study, a preprint posted online last week, tested the convalescent plasma of eight individuals immunized with Sinovacs CoronaVac injection, which uses inactivated virus to stir an antibody response. The plasma samples failed to efficiently neutralize the variant, study said.
More than a half-million Americans have died of the coronavirus while nearly 29 million cases have been reported.
