Dr. Scott Gottlieb told CNBC on Wednesday that millions of doses of a coronavirus vaccine could be available in the fall to be used in human trials.
It could be "enough to use in large-scale studies if you have an outbreak in American city where you might deploy the vaccine in an experimental protocol but deploy it nonetheless," Gottlieb said on "Squawk Box."
The hope would be to try to contain the outbreak and "validate whether or not the vaccine is truly safe and effective for mass inoculation of the population," the former Food and Drug Administration commissioner explained.
Gottlieb, who sits on the boards of Pfizer and biotech company Illumina, stressed that for the vaccine to be used in such a scenario, it must have cleared early stage clinical trials, demonstrating it was both safe and potentially effective.
The comments come one day after Pfizer reported first-quarter earnings, with the drugmaker saying Tuesday that it's taking steps to accelerate its work on a vaccine for Covid-19.
Pfizer, which is developing the vaccine alongside German firm BioNTech, hopes to begin human trials by the end of this month. Pfizer said it could potentially have millions of doses ready by year's end.
Gottlieb, who prefaced his answer about vaccines on CNBC by pointing to his Pfizer board role, said, "I'll be careful about saying too many specific things about Pfizer in particular."
"I think that there's going to be a number of companies that have substantial doses available in the fall," he said.
In addition to the pursuits of Pfizer and BioNTech, companies such as Moderna and Johnson & Johnson are working on developing a vaccine for Covid-19, which has infected more than 1 million people in the U.S., according to Johns Hopkins University data.
Manufacturing capability remains a key hurdle to widespread deployment of a potential Covid-19 vaccine across the world, said Gottlieb, who also is a CNBC contributor.
It will be "well into 2021 until anyone is going to have a vaccine available in the kinds of quantities that would be required to inoculate the entire United States or the entire European continent or other countries, low and middle-income countries," he said.
"We are a ways off in terms of having a vaccine available at .. that kind of scale," he said. "But in doses of millions, it could be available much sooner than that."
Gottlieb made his remarks on vaccine development Wednesday shortly before Gilead Sciences said it is aware of "positive data" from one of its studies looking at antiviral drug remdesivir as a potential treatment for the coronavirus.
— CNBC's Berkeley Lovelace Jr. contributed to this report.