“My expectation is, and I am a bit of an optimist, that we don’t find out that there’s only one of these vaccines that works, but rather two or three of them come through the trials looking as though they’re safe and effective,” Collins said. “They’ll have somewhat different characteristics of where they work best, so we might need to do some matching then of which vaccine goes to which particular population.”

Collins, who began leading the NIH in 2009 under then-President Barack Obama, said there’s enough money to rapidly manufacture 100 million vaccine doses by late fall and 300 million before January. The first people to get a vaccine will likely be frontline health workers and those with chronic conditions that put them at greater risk from the illness. Later, Collins said, the U.S. government will have to increase manufacturing to meet global demand, and distribute vaccines to countries particularly hard-hit by the virus.