The two viruses share a mutation known as N501Y that scientists worry could allow the virus to evade the immune protection generated by a vaccine.
The researchers made a version of the virus in the lab that carries the mutation. They tested it against blood taken from 20 people who had received two doses of the Pfizer vaccine as part of a clinical trial. In research posted online Thursday, they said they found “no reduction in neutralization activity” against the mutated virus.
The N501Y mutation appears to help the virus attach to human cells, which may partly explain why these new strains appear to be more transmissible. But it is just one of many mutations in both strains that scientists have worried could make the virus less susceptible to vaccines or treatments.
The study — conducted by researchers at Pfizer and the University of Texas Medical Branch — does not test the full array of these mutations. It also has not been peer-reviewed.
In a statement last month, Pfizer said it had performed similar tests on “multiple mutant strains. To date, we have found consistent coverage of all the strains tested.”It will be important to continue “monitoring of the significance of changes for vaccine coverage,” the researchers wrote.That’s because of “the possibility that a future mutation … might necessitate a vaccine strain change.” Both Pfizer’s and Moderna’s vaccines use genetic technology that would allow the vaccines to be quickly adapted to account for mutations, they noted.
At least 274,703 Covid-19 cases and a record 4,085 deaths tied to the virus were reported in the United States on Thursday, according to Johns Hopkins University’s tally of cases.
Thursday marked the first time that Covid-19 deaths in the US topped 4,000 in a single day.
There have been at least 21,579,567 cases of coronavirus confirmed in the US, according to the university. At least 365,317 people have died.
The totals include cases from all 50 states, the District of Columbia and other US territories, as well as repatriated cases.