Rising COVID-19 hospitalizations have put nine greater Minnesota counties in the federal high-risk pandemic category, though doctors continue to report mostly mild or even incidental infections among their inpatient cases.

The relative lack of severe cases among the 391 COVID-19 hospitalizations in Minnesota on Thursday remained the silver lining among otherwise worsening pandemic trends. The updated risk assessment by the Centers for Disease Control and Prevention on Thursday night put the seven-county Twin Cities metro area at moderate COVID-19 risk along with 21 other Minnesota counties.

Mask-wearing is recommended in public indoor spaces in Minnesota's nine high-risk counties — Dodge, Fillmore, Houston, Lake of the Woods, Olmsted, Rice, Roseau, Wabasha and Winona — to slow the spread of the coronavirus.

Mask-wearing and avoiding large groups in poorly ventilated indoor spaces are logical protective steps right now, said Dr. Andrew Badley, an infectious disease specialist at Mayo Clinic in Rochester, which is in the middle of the high-risk cluster.

"The number of people who are contacting me or my colleagues for advice is going up through the roof and that is always a harbinger of things to come," he said.

The viral load increased 17% over the past week in sewage samples from the Metropolitan Wastewater Treatment Plant in St. Paul, and Friday's report showed a shift in the type of coronavirus at work. The fast-spreading BA.2.12.1 variant, responsible for heightened pandemic activity in the northeastern U.S. this spring, accounted for 36% of the viral load in wastewater over the past week. That's an increase from 18% over the previous week.

Infection numbers have been rising as well. The Minnesota Department of Health reported another 2,919 cases Friday, which doesn't include the commonly used at-home rapid antigen tests.

The state on Friday also reported 12 COVID-19 deaths after reporting 11 on Thursday — the first back-to-back double-digit counts in weeks. Eleven of the 12 newly reported deaths were among seniors, reflecting a shift in trend.

Seniors account for 82% of Minnesota's 12,559 COVID-19 deaths but 72% of the deaths since June, when the severe delta coronavirus variant emerged and presented an increased risk to younger, unvaccinated adults. Seniors have made up 77% of the deaths since April.

Health officials encouraged Minnesotans to stay up to date with vaccinations and seek testing as soon as they are symptomatic to qualify for antiviral pills or monoclonal antibody infusions that can reduce the severity of their illnesses. Minnesota this week reported an on-hand supply of 20,000 courses of Paxlovid, which can reduce the risk of hospitalization for COVID-19 by 90%, as well as 10,000 courses that had been used.

The state this week consolidated testing activity, shutting down sites at the Roy Wilkins Auditorium in St. Paul and Stillwater Armory, and opening one at a St. Paul Midway location in the former Herberger's store. The site will offer more consistent hours than the other two, which had to close occasionally for events, a state health official said.

Badley said vaccinations and treatments likely explain some of the milder COVID-19 cases being seen at Mayo. Hospitalizations include patients who were admitted for other purposes and only discovered they had COVID-19 upon routine testing — though some of them end up needing treatment.

HealthPartners similarly reported this week that three-fourths of the patients with COVID-19 in its hospitals in Minnesota and western Wisconsin were admitted for other reasons and had no symptoms of infection.

On Thursday, only 35 of Minnesota's COVID-19 hospitalizations — 9% of the total COVID-19 patients — needed intensive care. That rate had been above 30% during severe waves earlier in the pandemic. The ICU number nonetheless reflects an increase from a low of 21 such patients in mid-April.

The CDC risk designation alerts counties when their COVID-19 levels could exhaust local hospital capacity. For now, overall hospital usage in Minnesota remains low. The state reported 1,038 ICU beds were occupied by COVID and non-COVID patients Thursday, compared with a peak of 1,235 last November.