‘‘I would still put my money on November/December,” he said, during a Congressional Hispanic Caucus Institute panel on global pandemics.
Fauci, 79, one of the most trusted faces of the coronavirus task force, said his informed projection was calculated based on where the clinical trial sites are in their studies, according to CNN.
He added that researchers need to see about 150 infections occur in a vaccine trial for it to be deemed safe and effective.
“Right now, the trials are over two-thirds enrolled – really close to full enrollment on one, and over full enrollment on the other,” Fauci said.
A vaccine could potentially come sooner than the expected timeframe based on those metrics, but it's likely that an answer about efficacy won't be ready until November or December, he added.
“It really depends on where the sites are and how many infections there are in a site,” Fauci told the news organization. “So you could get your answer sooner, or you can get your answer a bit later.”
Earlier this month, Fauci said he was not comfortable with rushing a vaccine through under Emergency Use Authorization unless it was shown in clinical trials to be "safe and effective."
He said that until a vaccine is ready, people should continue to wearing masks, maintain physical distance, and avoiding crowds to prevent future surges.
As of early Friday, the U.S. has seen more than 6,674,458 total coronavirus cases, and at least 197,633 deaths from the virus, according to data from Johns Hopkins University.
Fox News' Morgan Phillips contributed to this report