Although two ongoing clinical trials of 30,000 volunteers are expected to conclude by the end of the year, [Anthony] Fauci said an independent board has the authority to end the trials weeks early if interim results are overwhelmingly positive or negative.
The Data and Safety Monitoring Board could say, “‘The data is so good right now that you can say it’s safe and effective,'” Fauci said. In that case, researchers would have “a moral obligation” to end the trial early and make the active vaccine available to everyone in the study, including those who had been given placebos — and accelerate the process to give the vaccine to millions.
In trials of this size, researchers will know if a vaccine is effective after as few as 150 to 175 infections, said Dr. Robert Redfield, director of the Centers for Disease Control and Prevention, in a call with reporters Friday.
“It may be surprising, but the number of events that need to occur is relatively small,” Redfield said.
Researchers will continue to follow vaccinated volunteers for a full year to look for long-term side effects, Redfield said.
And Fauci acknowledged that cutting a trial short could undermine public confidence in COVID vaccines. One American in three is unwilling to get a COVID vaccine, according to a recent Gallup Poll.