“Small price to pay for protection against Covid,” said Dr. William Schaffner of Vanderbilt University Medical Center, a vaccine expert who wasn’t involved with the study.
He called the early results “a good first step,” and is optimistic that final testing could deliver answers about whether it's really safe and effective by the beginning of next year.
“It would be wonderful. But that assumes everything’s working right on schedule,” Schaffner cautioned.
Moderna’s share price jumped nearly 15 percent in trading after US markets closed. Shares of the company, based in Cambridge, Massachusetts, have nearly quadrupled this year.
Tuesday's results only included younger adults. The first-step testing later was expanded to include dozens of older adults, the age group most at risk from Covid-19.
Those results aren't public yet but regulators are evaluating them.
Fauci said final testing will include older adults, as well as people with chronic health conditions that make them more vulnerable to the virus — and Black and Latino populations likewise affected.
Nearly two dozen possible Covid-19 vaccines are in various stages of testing around the world.
Candidates from China and Britain’s Oxford University also are entering the final testing stages.
The 30,000-person study will mark the world’s largest study of a potential Covid-19 vaccine so far.