Renowned infectious disease expert Michael Osterholm on Monday spelled out exactly what Americans should expect to see from the coronavirus pandemic in the next few months, warning: “We are about to enter COVID hell.”

Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota and newly minted member of President-elect Joe Biden’s coronavirus advisory team, told CNBC’s “Squawk Alley” the number of daily new infections is “going to continue to increase substantially.”

“We have not even come close to the peak and, as such, our hospitals are now being overrun,” Osterholm said, cautioning the pressure on health services will soon become so high the quality of care they are able to provide will drop.

“The next three to four months are going to be, by far, the darkest of the pandemic,” Osterholm continued.

“I don’t think America quite gets this yet,” he said.

“This is going to get much worse. This is not to scare people out of their wits, this is to scare people into their wits to understand that because we still have control.

We can basically limit the contacts we have with people that will dramatically impact our ability of getting this disease.”

The U.S. on Sunday became the first country to surpass 10 million cases of COVID-19 — with an average of 108,000 people now being diagnosed with the disease every day.

The daily count will soon soar so high that Americans would soon look back at the 100,000 a day figure and “wish to be back there,” Osterholm added.

A glimmer of hope amid the pandemic came this week when Pfizer announced early data on its COVID-19 vaccine showed more than 90% effectiveness.

Osterholm described the progress as a “great, great finding” but cautioned against becoming too excited, noting how more data is needed to understand exactly what the statistic means — whether it’s to prevent serious illness or just milder symptoms.

“Until we have those pieces of information, we can’t really know how much of a game-changer this really is,” he said.