Moderna said it will conduct the trial at 87 study locations, all in the United States.
The experimental vaccine will be tested in 30 states and Washington, DC Around half of the study locations are in hard-hit states like Texas, California, Florida, Georgia, Arizona and North and South Carolina.
The United States has reported record numbers of new coronavirus cases in recent days, with much of the surge coming from those states.
The federal government is supporting Moderna's vaccine project with nearly half a billion dollars and has chosen it as one of the first to enter large-scale human trials.
Tensions between the company and government scientists contributed to a delay of the trial launch, Reuters reported earlier this month.Shares of Moderna rose about 2.5% on Nasdaq at midday.