CNN  — 

The US could see an explosion of Covid-19 cases as fall and winter set in, one expert says, joining a chorus of health officials who have warned about the challenges of the coming months.

Two things will likely help drive that expected winter surge, according to Dr. Chris Murray, director of the University of Washington’s Institute for Health Metrics and Evaluation (IHME).

“First, as case counts have come down in some states, we tend to see that people become less careful, they tend to have more contact,” he said. “But then the most important effect is the seasonality of the virus, that people go indoors, transmission happens more.”

The IHME model indicates that the country is currently seeing about 765 daily deaths from Covid-19, but that number could jump to 3,000 daily deaths by late December.

More than 204,000 Americans have already died from the virus since the start of the pandemic and more than 7 million have been infected, according to Johns Hopkins University. At least 24 states are now reporting a rise in new cases compared to the previous week, mostly across the US heartland and Midwest, according to data from Johns Hopkins.

Murray’s warning is one that’s been repeated from several other health officials in recent months. Over the summer, the US Centers for Disease Control and Prevention director warned the fall and winter could be “one of the most difficult times that we experienced in American public health.” And this week, leading infectious disease expert Dr. Anthony Fauci urged American cities and counties to prepare for “the challenge” of fall and winter.

It’ll be especially challenging moving into the new season, Fauci said, with a daily average of more than 40,000 cases nationwide.

“You don’t want to enter into the fall and winter with a community spread at that level, because if you do, you got a difficult situation that’s going to be really challenging,” Fauci told JAMA Editor in Chief Dr. Howard Bauchner.

Murray says the IHME model shows a “huge surge” expected to take off in October “and accelerate in November and December.”

“There’s a real risk that winter surge has already started in Europe,” Murray said. “Cases are exploding there. So we know it’s coming and we expect it to hit the US pretty soon.”

Florida clears bars and restaurants to fully reopen

Bars and restaurants in Florida are now allowed to operate at full capacity, just as the number of coronavirus cases nears 700,000.

A day after Gov. Ron DeSantis announced the state was moving into the third phase of reopening, health officials reported at least 2,795 new cases of Covid-19 and at least 107 deaths.

The state has reported at least 698,682 Covid-19 cases and 14,022 deaths since the pandemic started, according to the Florida Department of Health.

Miami Mayor Francis Suarez said removing state restrictions on bars and restaurants is “an acceleration” and “it’s a lot faster that we had planned.”

“We’ll see in the next couple of weeks whether he’s right about his perspective. But if he’s wrong about his perspective … it’s going to be very, very, very difficult for him and it’s going to be a very difficult time, because it’s in the middle of flu season,” Suarez told CNN on Saturday.

Restaurants can’t be limited by local governments to operate at less than 50% of their indoor capacity, according to the governor’s order. If local governments opt to restrict restaurants to less than 100% of their capacity, they have to provide “the justification and they’ve got to identify what the costs are involved with doing that are,” the governor said.

DeSantis said he wants the state to be able to offer a “full Super Bowl” in February.

Dr. Saju Mathew, a primary care physician and public health specialist, said on CNN Saturday that he was shocked by the governor’s decision.

“I just see no way that that would be possible” to host the Super Bowl. “People will be coming from so many different states … If you group in a lot of different people in a tight space, how are you going to be able to socially distance? I think it’s a very dangerous move.”

Nationwide, the average number of new cases in the past week has climbed over the last two weeks, most recently Friday to 44,111, figures from Johns Hopkins University show. It’s up more than 28% since September 12, when it was 34,307.

Fauci: Covid-19 vaccinations could start in November

Fauci says Covid-19 vaccinations could “very likely” start in November or December. But it could still be a while until the US is back to normal.

“By the time you get enough people vaccinated….so that you can start thinking about maybe getting a little bit more towards normality, that very likely, as I and others have said, will be maybe the third quarter or so of 2021,” he told Bauchner. “Maybe even into the fourth quarter.”

In the meantime, Fauci and other leading experts have urged residents to continue heeding safety guidelines and wearing masks, keeping a distance, avoid crowded places and washing their hands.

The measures could be life-saving.

CDC Director Dr. Robert Redfield said this week preliminary results of the first round of a study show more than 90% of the US population remains susceptible to Covid-19. And a study published Friday in The Lancet found as of July, fewer than 10% of people in the US had antibodies to the virus.

“This research clearly confirms that despite high rates of COVID-19 in the United States, the number of people with antibodies is still low and we haven’t come close to achieving herd immunity,” one of the study authors, Dr. Julie Parsonnet, a professor of medicine at Stanford University, said in a statement.

“Until an effective vaccine is approved, we need to make sure our more vulnerable populations are reached with prevention measures.”

CNN’s Jay Croft, Lauren Mascarenhas, Melissa Alonso, Shelby Lin Erdman, Andrea Kane and Konstantin Toropin contributed to this report.