COVID-19 is beating a retreat in Minnesota, with doctors voicing more optimism than ever about the state's pandemic outlook.

New infections are falling to levels not seen since last summer. Hospitalizations are dropping. And the number of reported deaths this month likely won't reach half the total from last May, when the state passed the grim pandemic milestone of 1,000 fatalities.

Vaccines are the clear driver, with two-thirds of adults across the state having received at least one dose.

"I do believe, in the United States at least, the potential for a very dramatic national surge is off the table because of the vaccination levels," said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

The pandemic isn't over. With too many still unvaccinated, the virus that causes COVID-19 illness will continue to see outbreaks in parts of the state and country, resulting in more serious illnesses and deaths.

Variants of the virus could emerge that significantly reduce vaccine protection. And if vaccine-based immunity wanes, booster shots could be required.

Yet doctors say there's reason to think the recent case declines will continue — particularly if more people get vaccinated. Some also point to help from immunity based on previous infections as well as warming weather that promotes outdoor gatherings, where transmission is less likely.

"I think we are getting to the point where there are very few targets for new infections to occur," said Dr. Mark Sannes, an infectious disease specialist at HealthPartners.

"The potential hosts for a virus to land and cause new infection — the odds of that happening are shrinking every day. … Our vulnerability has gone down so much because of the number of people now protected by the vaccine."

The Minnesota Department of Health on Saturday reported 343 new infections and another 10 deaths linked to COVID-19. With the latest numbers, the seven-day rolling average for net new cases fell to 397, the lowest reading since late June, according to the Star Tribune's coronavirus tracker.

In March, Minnesota started to see a surge in cases with the spread of a more contagious form of the pandemic virus called B.1.1.7. The variant caused a large case surge in Michigan, prompting some to fear a U.S. spike in serious illnesses and deaths similar to what hit the United Kingdom last winter.

But most states didn't report problems. Even in Minnesota, which saw a surge in COVID-19 hospitalizations this spring, case counts and new admissions have steadily declined since April.

"We were very concerned," said Kris Ehresmann, the state's director for infectious diseases. "We have gone from being in the, kind of, red zone all the time to seeing our statewide rate of new cases decreasing by leaps and bounds every week."

Note of caution

In February, Osterholm likened the threat from B.1.1.7 to a category 5 hurricane. Michigan was rocked by just such a storm, he said last week, while Minnesota absorbed a significant, but less intense hit.

There's no clear explanation, Osterholm said last week, for why the variant's impact was muted elsewhere. He said on his podcast: "My level of humility for predicting the future has taken on even a new measure of caution."

Variants remain somewhat unpredictable, so they continue to provide a note of caution for the pandemic outlook, said Richard Danila, an epidemiologist with the Minnesota Department of Health. Ehresmann stressed that the state still needs higher rates of vaccination.

But the level of vaccine-based protection, plus immunity from previous infections, means that Minnesota is "approaching a threshold where widespread community transmission is not going to happen anymore," said Dr. David Boulware, an infectious disease specialist at the University of Minnesota Medical School.

While outbreaks will pop up, Boulware expects daily counts for new infections in Minnesota likely will remain in the hundreds, not the thousands. And depending on how many more people get vaccinated, he said, "I think we're just going to continue to go down with the total case numbers."

Warming weather is helping, since coronaviruses tend to spread more readily during colder months, said Dr. Jonathan Temte, an associate dean at the University of Wisconsin School of Medicine and Public Health. Summer means "we can be reasonably confident the worst is behind us," Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, said via e-mail. "The seasonal stuff we are now benefiting from will turn against us come the fall ... so get your shot."

More than 2.9 million state residents have now received at least one dose of vaccine. That's 64% of those age 16 and older.

'It's a new day'

If a significant number of Minnesotans remain unvaccinated, doctors fear that communities will face very different risk levels, with statewide case trends overstating the risk in high-vaccination areas and understating it where few have been immunized.

That dynamic is already evident, Sannes said, across the eight hospitals operated by HealthPartners. Unvaccinated people accounted for all but 10 of the roughly 1,200 patients hospitalized with COVID-19 between January and April.

Near the end of May 2020, HealthPartners was treating 104 patients hospitalized with COVID-19, including 40 who required intensive care. On Friday — exactly one year later — HealthPartners reported 27 hospital patients with the virus, including just six in the ICU.

"We have no hospitals with 10 or more patients with COVID," said Sannes, who added that it was unusual — if not unprecedented — for all eight hospitals to report pandemic patients in single digits.

Just as health officials cautioned people about letting down their guard during earlier periods of optimism, they're now stressing that people shouldn't take the current case drop as reason to pass up their shots.

"Unvaccinated people will continue to get infected, they will continue to get seriously ill and they will continue to die," Osterholm said.

The state seems to be at an inflection point, where COVID-19 becomes more of a community illness than a threat to the health care system, said Dr. John Hick, an emergency physician with Hennepin Healthcare. After staying away due to virus fears, more patients are returning for care, said Dr. Kim DeRoche, the physician chief for primary care at M Health Fairview.

For pediatricians, one clear sign of the shift is that kids are showing up again with colds, strep throat and other common illnesses that largely subsided when schools were using distance learning, said Dr. Marilyn Peitso, president of the Minnesota Medical Association.

Social distancing and other measures still have a place, Peitso said, since vaccines aren't yet approved for young children and people with certain health problems. She hopes new state incentives will persuade holdouts to get their shots.

"We have reason to celebrate," Peitso said. "It's a new day."

Christopher Snowbeck • 612-673-4744