Johns Hopkins University says the total number of confirmed coronavirus cases in the United States since the start of the pandemic surpassed 30 million on Wednesday.
There are fears of a fourth wave of infections in the country as many states move to ease restrictions.
The number of daily new cases in the US has declined since the peak in early January, when about 300,000 infections were reported.
But Dr Rochelle Walensky, the Director of the Centers for Disease Control and Prevention, said on Wednesday that she continues to be worried about the latest data.
She said the most recent seven-day average is nearly 55,000 cases per day and the figure for new hospitalizations is about 4,600 per day.
Walensky also said, "If we choose to invest in prevention right now, we will ultimately come out of this pandemic faster and with fewer lives lost."
Michigan and New Jersey are among the states seeing an uptick in new infections after easing restrictions.
Health experts warn that the rapid easing of restrictive measures could lead to a resurgence of new cases.
They have also expressed concern that the spring holiday season, which begins later this month, could increase the risk of a rebound of infections in the US.