Pfizer says tests show its COVID-19 vaccine is effective against new, more contagious variant

Pfizer vaccine doses
(Image credit: Patrick Hertzog/AFP/Getty Images)

A new, more transmissible variant of the coronavirus, first discovered in England, is spreading around the U.S. — Texas' first confirmed case was reported in Harris County on Thursday. But new research from Pfizer and the University of Texas Medical Branch in Galveston suggests the Pfizer-BioNTech COVID-19 vaccine can protect against the new B117 strain. The researchers reported Thursday night that lab tests on blood samples from 20 vaccinated people showed their antibodies successfully fended off the new strain of the virus.

The new findings are preliminary and haven't yet been reviewed by outside experts, but "it was a very reassuring finding that at least this mutation, which was one of the ones people are most concerned about, does not seem to be a problem" for the vaccine, Pfizer chief scientific officer Dr. Philip Dormitzer told The Associated Press. Pfizer's coronavirus vaccine, like most of the others in use worldwide, trains the body to recognize and fight off the spike proteins that the coronavirus uses to infect cells.

The NF01Y mutation found in the U.K. and a different strain in South Africa was already expected to be susceptible to the new vaccines. Infectious disease experts are more worried about how the vaccines will work on another mutation, E484K, found in the South African variant. Pfizer said its study found the vaccine effective against 15 more possible mutations, but not yet E584K, which is next on the list to study.

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Lab studies show that the E584K mutation, also found in Brazil, "could make people's antibodies less effective at neutralizing the virus," Stat News reports. "The mutation seems to help the virus disguise part of its signature appearance, so the pathogen might have an easier time slipping past immune protection." But even if the vaccines are less effective, they won't be useless, molecular virologist Ramón Lorenzo-Redondo at Northwestern University's Feinberg School of Medicine told Stat News. "With one mutation or even three mutations, it's expected the antibodies will still recognize this variant, though they might not recognize it as well as other variants."

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Peter Weber

Peter Weber is a senior editor at, and has handled the editorial night shift since the website launched in 2008. A graduate of Northwestern University, Peter has worked at Facts on File and The New York Times Magazine. He speaks Spanish and Italian and plays bass and rhythm cello in an Austin rock band. Follow him on Twitter.