Washington, Jun 29 (IANS): US Secretary of Health and Human Services Alex Azar said the "window is closing" for the country to curb the surge of coronavirus cases.

"Things are very different from two months ago... So it is a very different situation, but this is a very, very serious situation and the window is closing for us to take action and get this under control," Xinhua news agency quoted Azar as saying in a CNN interview on Sunday.

He encouraged all Americans to follow the government's guidelines about social distancing and wearing of masks.

Azar said that in many southern states where the virus is spiking, including Florida and Texas, the majority of the cases were people under 35, and a large number of those will be asymptomatic.

"We've got our fatality rates and our hospitalization rates are the lowest they've been in two months, but this is a very serious situation," he said.

Azar said the administration is working with local authorities and states to understand why the virus is surging in certain areas.

He noted that treatments like steroids and remdesivir were now available for COVID-19, and encouraged people who have had the virus to donate plasma to increase the supply.

On Friday, the US reported the highest number of new cases in a single day, with at least 40,173 new infections. The previous daily high was reported on Thursday.

Thirty-six states were reporting a rise in COVID-19 cases.

As of Monday morning, the US accounted for the world's highest number of infections and fatalities with 2,548,143 and 125,799, respectively.