Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX) said on Thursday their COVID-19 vaccine is around 91% effective at preventing the disease, citing updated trial data that included participants inoculated for up to six months.
The shot was also 100% effective in preventing illness among trial participants in South Africa, where a new variant called B1351 is dominant, although the number of those participants was relatively small at 800.
While the new overall efficacy rate of 91.3% is lower than the 95% originally reported in November for its 44,000-person trial, a number of variants have become more prevalent around the world since then.
Pfizer’s CEO Albert Bourla said the updated results, which include data on more than 12,000 people fully inoculated for at least six months, positions the drug makers to submit for full U.S. regulatory approval.
The vaccine is currently authorized on an emergency basis by the U.S. Food and Drug Administration.
The trial data "provide the first clinical results that a vaccine can effectively protect against currently circulating variants, a critical factor to reach herd immunity and end this pandemic for the global population," Ugur Sahin, chief executive officer at BioNTech, said in a statement.
Experts fear new variants of COVID-19 from South Africa and Brazil may be resistant to existing vaccines and treatment. More than 300 cases of the South African variant have been detected in more than 25 U.S. states and jurisdictions, according to federal data.
PFE shares began Maundy Thursday down four cents to $36.19, while BNTX gained $2.58, or 2.4%, to $111.77
