DULUTH – More than 400 new COVID-19 cases have been confirmed in St. Louis County over the past two weeks, an increase the county's public health director attributes mostly to the return of Duluth's college students.

The state Health Department reported 10 virus-related deaths in the northeastern Minnesota county over the past week. Fewer residents reportedly died from COVID-19 during the months of July and August combined.

"Typically when you see cases increase in communities, even if it's within a young and healthy population, it generally then pervades into the more vulnerable population," said Amy Westbrook, St. Louis County's public health director.

A total of 1,480 cases have been reported in the county, 17% of them in the past week. St. Louis County, like others across Minnesota, has continued to see COVID-19 infections rise fastest among those aged 15-24.

Dr. Andrew Thompson, an infectious disease specialist at St. Luke's Regional Health Care System in Duluth, said he believes the opening of the University of Minnesota Duluth and St. Scholastica campuses likely played a role in that increase. But he also noted that a higher proportion of young adults may live with roommates or hold jobs they can't do from home.

"I think initially there was a lot of willingness to go to pretty significant measures to stop the spread of this virus," he said. "My sense is people have just got tired of it and are not distancing as they should be."

As of Sept. 17, 44 students had been tested through UMD's health services, and 12 tests were positive. Those tested off campus are not included in the university's weekly update.

The 10 county residents who most recently died from the virus were in their 70s or older. All but one woman lived in care facilities.

For the first time since August, Minnesota's hospitalization numbers rose above 300 Wednesday. Thompson noted the local positivity rate of diagnostic testing has also steadily risen, though St. Louis County's remains below the state average.

"We're hoping these are not trends we continue to see," Westbrook said.

Though a majority of St. Louis County's cases are reported in Duluth, recently communities farther north have seen a wider spread of the virus. Congregate care facilities in Chisholm, Ely, Eveleth and Virginia have been exposed to the virus, according to state data.

Cases in other parts of Minnesota's geographically largest county, like the area surrounding Orr, are more puzzling to public health officials, who chalk up new cases to community transmission.

Though many of the county's school districts outside the Duluth metro area started class in person, some — like Ely and Hibbing — have switched to more cautious learning models as the cases in the region began to grow.

"I think what we initially thought was a much more urban problem is not so," Thompson said.

Smaller communities around Minnesota have had outbreaks traced to weddings, funerals or other gatherings. Health officials have repeatedly urged Minnesotans to wear masks and social distance, even when it's not required by law.

As the temperatures drop and more people spend time indoors, Thompson said there will be a bigger risk of transmission and other respiratory infections like the flu.

He added that though doctors have found better ways to diagnose and manage sick patients, "there have been no breakthroughs."

"I am actually very concerned our numbers are going to keep increasing and put a big strain on our health care system," Thompson said. "People are going to die as a result of it."