Dr Anthony Fauci, speaking on Good Morning America, said a national lockdown to curb the spread is not necessary if people wear their masks and social distance.
He also said a vaccine could be available to the general public by early April or May.
He encouraged Americans to “hang in there” until a vaccine is ready.
Several state leaders are ramping up restrictions amid the surge in cases.
In Ohio, Governor Mike Dewine ordered businesses to post their mask guidance outside their doors. Bars and restaurants can remain open for now but that will be reviewed next week.
In Indiana, the governor announced crowd sizes will be limited starting this weekend in most counties. The state’s mask mandate is also being extended for another month.
And in New York, bars, restaurants, and gyms must close by 10 p.m. beginning Friday.