By Maggie Fox and Deidre McPhillips, CNN

(CNN) — The coronavirus numbers don’t look so good this week. New Covid-19 diagnoses are up in about half of US states over the past week. Hospitalizations are up in 11 states, and deaths have risen in 17 states.

US coronavirus cases have plateaued in recent weeks, holding on to about half of the growth from this summer’s latest surge.

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While new cases have fallen in some states, they’re rising in others, particularly some region’s cold-weather states.

Southern states that were a large driving force behind this summer’s surge now have some of the lowest case rates. Two months ago, Florida and Texas together accounted for nearly a quarter (22%) of all new cases. Now, those two large states account for just 6% of all cases.

Florida sliced new cases to a 10th of what they were two months ago and Texas to a fifth.

That should sound like good news. But with less dramatic decreases in other, less populous states — and slight increases in some others, particularly in the Northeast and Mountain regions — overall US numbers are holding steady on the whole.

It’s confusing, and the numbers may be sending a mixed message to people. They are not, however, sending a mixed message to epidemiologists, who do not foresee a good winter for the US or for the world.

Too many people remain unvaccinated, and too many continue to defy and even fight advice to wear masks when indoors with other people. This dangerous combination might mean more surges, even if not as high as in the recent past, and in areas beyond those currently seeing rising cases.

“I don’t know what’s going to happen over the next few weeks. But I have a feeling it’s not going to be pretty,” Michael Osterholm, who heads the center for Infectious Disease Research and Policy at the University of Minnesota, told CNN.

“Today is a really sad day,” epidemiologist Ali Mokdad, who has been tracking the coronavirus pandemic since the beginning at the University of Washington, told CNN. “Cases are going up. It was coming down. This is at a time when the United States has all the tools we need to prevent a surge, all the tools we need to save lives. We have the best vaccines, and we have plenty of them,” he said.

“And people are not willing to get them.”

False sense of security

Mokdad said states such as Florida have a false sense of security.

“Florida has a large population of the elderly, who went and got vaccinated. And the young people simply got infected. So the virus ran out of people to infect,” he said.

But he said immunity on both groups is waning.

“There will be a lot of winter travel to Florida,” he said. “Infections will start all over again,” he predicted. “We are so interconnected.”

Diagnoses and hospitalizations are both headed upward in Michigan, with hospitalizations up 20% in the past week, according to state data.

“Metro Detroit once again is becoming a hotspot,” Dr. Nick Gilpin, director of infection prevention and epidemiology at Beaumont Health, a health system in southeast Michigan, told a news conference Thursday.

“I have a feeling we’ll be in this world for the next couple months because I don’t see much that can change this unless people start radically changing behavior. This could be a four or five month affair,” Gilpin added.

Like Mokdad, Gilpin blames the unvaccinated and a refusal to wear masks. It’s hitting hospitals and clinics hard, he said.

“I mean, it’s brutal. No one wants to see these Covid patients this late. But we’re masking up and trying to help people get better,” Gilpin said.

“That said, there’s probably no hospital in the state that isn’t dealing with staffing shortages. It’s difficult, especially as we look to a fourth surge that could last through the winter. This surge is shaping up more to be a marathon than a sprint.”

Millions still unvaccinated can fuel new surges

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In Colorado, where cases were up 30% in the past week, according to Johns Hopkins University data, Gov. Jared Polis declared the entire state to be at high risk of Covid-19 transmission or exposure and signed an executive order saying everybody over 18 was eligible for a booster dose of vaccine.

“We want to ensure that Coloradans have every tool they need to protect themselves from this deadly virus and to help reduce the stress on our hospitals and health care workers. Every Coloradan is now eligible to get the booster so they can protect themselves and their families,” Polis said in a statement.

Mokdad approves. “Science is telling us we need three doses to be immune,” he said. “We are losing our credibility as scientists unless you say it — we need three doses to be protected.”

The US Food and Drug Administration and the US Centers for Disease Control and Prevention have OK’d booster doses for most US adults, and the FDA is considering extending authorization for booster doses of Pfizer’s vaccine to all adults.

Osterholm thinks boosting people will help — but says it’s far more important to get more people vaccinated in the first place.

“If we see upticks in L.A. or New York City, we could just as easily find ourselves back to where we were. At this point, there’s no evidence of that happening,” he said in his podcast this week.

“But I must tell you that given the rates of vaccination … we surely could see major surges in both of those metropolitan areas where with the population density being what it is, could really, truly raise the number of national cases in short order,” he added.

An estimated 60 million Americans remain unvaccinated. That’s plenty of people who can help fuel new surges, Osterholm said.

“Overall, there’s still a lot of human wood left for this coronavirus forest fire to burn,” he said.

Even in states, cities and counties with high vaccination rates, enough people remain unvaccinated or undervaccinated to help keep the virus spreading. And if immunity is waning as quickly as some studies indicate it may be, Osterholm fears more breakthrough infections, even among the vaccinated.

What could be ahead this winter

Osterholm is pessimistic about the coming weeks. “That fact, combined with Delta, schools and upcoming holidays, has me skeptical that we won’t be seeing new hotspots emerge in this country over the next several weeks and months. So where do I see us going? I think we will continue to see surges. They may not be nearly as high as the ones we’ve just had, but they will occur.”

And they will not be restricted to the current hotspots, Mokdad predicted. The holidays will make sure of that. “People are moving out and about like there is no Covid-19,” he said.”We are going to see Americans traveling — Thanksgiving and then all the way through New Year. We are going to see a surge, and that surge is going to be very bad.”

AAA is predicting travel for Thanksgiving will rebound to near pre-pandemic levels, with 53.4 million Americans expected to travel for the holiday — a 13% increase from last year.

And plenty of states have such low vaccination levels that they’re bonfires waiting to be ignited, Mokdad said.

“I mean, West Virginia [is] 41.1% fully vaccinated. So 60% of the population, at least, don’t have immunity against infection,” he said.

“So, what do you expect? We’re going to have a surge. If you look at Montana, 51%. Wyoming, 44.6%. I mean, you could go on and on. There’s so many states right now below 50. Louisiana, 48.1%. Alabama, 45.2%.”

These same states, Mokdad and Osterholm both pointed out, have populations largely resistant to mask use, as well.

“Nobody is listening,” Mokdad said morosely. He said he and fellow epidemiologists were discussing how they could bring attention to the dire situation.

“Some of us we were talking about going on a hunger strike. We are really frustrated. It’s depressing that we know how protect our population and we are not doing it,” he said.

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