Bill Gates, co-founder of Microsoft, said people might need multiple doses of a potential coronavirus vaccine to immunize themselves from the virus.
"None of the vaccines at this point appear like they'll work with a single dose," Gates said. "That was the hope at the very beginning."
A 30,000-person study of the Moderna vaccine, which requires two doses a month apart, will begin July 27.
"If what you're trying to do is block all the transmission, then you need to get 70-80% coverage on a global basis. So it's unbelievably big numbers," Gates said.
Gates said the FDA is the "gold standard of regulators, and their current guidance on [preventing an unsafe vaccine] ... is very, very appropriate."
? Gates announced in April he would fund factories working on the top seven vaccine candidates.