The Covid-19 vaccine being developed by Pfizer Inc. and BioNTech SE prevented more than 90 percent of infections in a study of tens of thousands of volunteers, the most encouraging scientific advance so far in the battle against the coronavirus.
Eight months into the worst pandemic in a century, the preliminary results pave the way for the companies to seek an emergency-use authorization from regulators if further research shows the shot is also safe.
Pfizer shares extended gains in premarket trading, rising about 7 percent, with BioNTech American depositary receipts up about 11 percent.
The findings are based on an interim analysis conducted after 94 participants contracted Covid-19. The trial will continue until 164 cases have occurred. If the data hold up and a key safety readout Pfizer expects in about a week also looks good, it could mean that the world has a vital new tool to control a pandemic that has killed more than 1.2 million people worldwide.
Pfizer expects to get two months of safety follow-up data, a key metric required by U.S. regulators before an emergency authorization is granted, in the third week in November. If those findings raise no problems, Pfizer could apply for an authorization in the U.S. this month. A rolling review began in Europe last month, and Sahin said regulators there are working with BioNTech to “further accelerate the process.”
So far, the trial’s data monitoring committee has identified no serious safety concerns, Pfizer and BioNTech said.
Pfizer had originally planned to conduct a first analysis of trial data after just 32 virus cases had occurred in the trial, which has enrolled 43,538 volunteers in multiple countries. Analyzing the data that early proved controversial among medical experts. Other companies working on vaccines planned to wait longer before scrutinizing trial information.
After discussion with U.S. regulators, Pfizer and BioNTech said they recently elected to drop the 32-case analysis and conduct the first analysis at a minimum of 62 cases, one of several changes made in the trial-analysis plan.
While Pfizer conducted those negotiations, it paused testing of participant samples for the virus, said Gruber. By the time Pfizer had made the changes in the trial plan and restarted virus testing a few days ago, some 94 cases had occurred, far more than the trial needed to meet the new threshold.