Two new federal studies with Minnesota co-authors backed continued COVID-19 vaccinations — with one finding a spike in hospitalizations among unvaccinated people ages 18-49 and the other finding no elevated rate of mortality in the vaccinated population that could be traced to side effects from the shots.

The hospital study co-authored by Minnesota's epidemiologist, Dr. Ruth Lynfield, showed that 71.8% of COVID-associated hospitalizations in 14 states were among the unvaccinated during the period this summer when a fast-spreading delta variant emerged as the dominant strain of the coronavirus. More than 43% of those unvaccinated hospitalizations were among people 18-49.

"We have been worried about that age group because we have seen lower vaccine uptake and we know that a lot of Minnesotans do have conditions that put them at increased risk for severe disease, including obesity and many other chronic conditions," Lynfield said.

The report from the Centers for Disease Control and Prevention (CDC) came amid hopeful signs in Minnesota that the delta-fueled pandemic wave this summer and fall is easing. The state's reported positivity rate of recent COVID-19 diagnostic testing dropped from a recent peak of 8.4% to 7.9%, and the number of COVID-19 hospitalizations has dropped from 1,008 on Oct. 15 to 915 on Thursday.

The state nonetheless on Friday reported 2,150 more coronavirus infections and 22 COVID-19 deaths, including two people in their 40s and a St. Louis County resident in the 35-39 age range. While 86% of Minnesota's 8,537 COVID-19 deaths have been among seniors, the median age has declined slightly as more deaths of younger people are reported.

Minnesota responded to the latest wave with a $200 vaccine incentive for new recipients ages 12-17 who complete the two-shot series by Nov. 30.

The state also mobilized the Minnesota National Guard to open free COVID-19 testing sites in Stillwater and six other communities, using the rapid antigen testing that can provide results in a couple hours and work best in symptomatic people. PCR molecular tests are recommended as more accurate options for people with viral exposure risks who don't have symptoms.

More than 300 Guard members are trained and ready to provide temporary staffing support in skilled nursing facilities. That could ease the burden on hospitals that are struggling amid the COVID-19 demand to transfer patients out and free up beds.

The latest steps follow what appears to be a peak of the latest COVID-19 wave in Minnesota — mimicking Gov. Tim Walz's four-week pause on social and indoor activities last fall that was designed to protect the state until a vaccine became available but also took effect after infection numbers were already declining.

State Health Commissioner Jan Malcolm said the latest measures might be coming after infections already have peaked but play an important role in driving down COVID-19 cases ahead of the typical flu season.

"It's really up to us whether this trend that we hope we're starting to see of a plateau continues or not and how fast the decline is. ... So in no way do I think it is too late by any means," she said.

The second CDC study published Friday examined seven U.S. health systems, including Bloomington-based HealthPartners, and found that rates of non-COVID deaths were higher among the unvaccinated population when adjusted for age, sex, race and other demographics.

The lack of an elevated death rate in the immunized population reinforced to the researchers the safety of COVID-19 vaccines, which have been provided to more than 3.6 million people 12 and older in Minnesota — or 76% of the state's eligible population, the CDC reports.

Jeremy Olson • 612-673-7744