COVID-19 death counts are surging once again, with Minnesota on Saturday reporting 75 more fatalities for a weekly record of 399 — far surpassing the previous high of 327 deaths set during the third week of November.

The number of new cases each day remains very high as well, health officials say, although the growth rate has been relatively stable the last two weeks.

Amid optimism over vaccine development and emerging treatments, the University of Minnesota this month is launching a study exploring the potential for a widely used diabetes medicine to help prevent severe COVID-19. But worries persist about hospital capacity with reports of heavy travel during the Thanksgiving holiday weekend.

"You look at those and your heart sinks, because you know what's coming," said Dr. Heidi Erickson, a critical care physician at Hennepin Healthcare. "When you see that kind of widespread travel, that is almost certainly going to translate into more cases and more hospital admissions."

Doctors and nurses are feeling the strain.

"There's just such a high burden of moral distress with not only the sheer volume of work, but also just the amount of suffering that health care workers are bearing witness to — watching their patients and families suffer and grieve," Erickson said. "And in some instances, those health care workers are having their own personal experiences with that, in addition to bearing witness to it."

The Minnesota Department of Health reported 6,337 new coronavirus cases Saturday, a one-day tally that pushed the seven-day rolling average to 5,894 — down from Friday, but up slightly from a week ago, according to the Star Tribune's coronavirus tracker. The seven-day average for cases in Minnesota peaked on Nov. 20 at just over 7,000 cases per day.

Over the past week, seven-day averages for new cases in the state have fluctuated from 5,400 to 6,300 per day, a pattern playing out across the country, said Dr. Thomas Tsai of the Harvard T.H. Chan School of Public Health.

"I don't think we've turned the corner of this third wave, rather this is a sawtooth on the way up to some undetermined peak," Tsai said. The rate of increase going forward might not be as fast, but "going constantly high in cases is still a bad thing."

The full risk of transmission during the Thanksgiving holiday won't show up for weeks, said Kris Ehresmann, the state's director of infectious diseases.

"While we have stabilized, we are again stable at the edge of the cliff," Ehresmann wrote in an e-mail. "Viral activity in all our communities is high and it won't take much to put us back where we were just over a week ago."

Minnesota is seeing a rolling seven-day average of about 220 new hospital admissions and 39 new ICU admissions per day, Ehresmann said. The share of COVID-19 patients in ICU beds and general hospital units has held steady over the past week, said Dr. Rahul Koranne, chief executive of the Minnesota Hospital Association.

"We remain on high alert," Koranne said. "We are still watching and waiting to see what the aftermath of the travel and Thanksgiving holiday will bring."

Drug holds promise

University of Minnesota Medical School researchers on Thursday published results showing that use of metformin, a generic drug commonly used for managing blood sugar in diabetes patients, was associated with significantly reduced risk of COVID-19 death in women. The findings, which were based on a review of de-identified patient data from Minnetonka-based UnitedHealth Group, bolster a study being launched this week.

Metformin has been used for decades, so doctors know how to use it safely in patients, including pregnant women and children, said Dr. Carolyn Bramante, an assistant professor in the department of medicine at the U Medical School. Not only is the drug's safety profile "compelling," Bramante said, the medicine is widely available and inexpensive.

The retrospective study published in the Lancet Healthy Longevity looked at about 6,000 patients with Type 2 diabetes or obesity who were hospitalized with COVID-19. It found that women who had filled a 90-day prescription before hospitalization had a 21% to 24% reduced likelihood of mortality compared with women in the study who weren't taking the medicine. There wasn't a significant reduction in mortality among men, according to results that originally were released in June.

"What we want to understand is: If we give metformin to someone who is not currently taking it, and doesn't necessarily have a reason for it, will it prevent severe COVID-19 disease?" Bramante said.

The U will be the lead site for the study, which will include clinics operated by UnitedHealth Group in Colorado and Indiana.

It's "entirely too early" for doctors to start prescribing metformin just for COVID-19, said Dr. Ken Cohen, an executive director in research and development at UnitedHealth Group. But the results thus far have been promising, and the pilot study could lead to a bigger research effort.

"You now have a public health emergency that is causing us to look for any effective therapies, and some of those effective therapies could be … generics that have been available forever," Cohen said.

UnitedHealth Group, which is parent company of the large health insurer UnitedHealthcare, is backing several research projects related to the pandemic. The company is working with the drug company Johnson & Johnson on enrollment for a coronavirus vaccine study.

The promise of the vaccines is encouraging, but people should guard against becoming complacent with social distancing and other behaviors that can reduce the virus spread, Erickson said.

"I had more patients die last week alone … than in the preceding several months," she said Friday.

Residents of long-term care and assisted-living facilities accounted for 40 of the deaths announced Saturday, and 2,599 deaths since the start of the pandemic. Since March, the state has reported 345,281 positive cases, 18,059 hospitalizations and 3,920 deaths.

Minnesota is in the midst of a sustained COVID-19 surge, and doctors don't expect it to ease soon — even though the state's hospitalization numbers declined a bit last week, said Marilyn Peitso, president of the Minnesota Medical Association.

"None of us has a crystal ball … " Peitso said. "But I don't think any of us should be fooled into thinking that the worst is over."

Christopher Snowbeck • 612-673-4744