Rising numbers of COVID-19 cases and outbreaks in Minnesota schools are narrowing the list of counties where the virus is spreading at low enough rates to allow for full, in-person instruction.

Statewide, more than 500 schools had at least one positive case in the last two weeks, and 24 public and private schools reported outbreaks with at least five positive cases, according to Minnesota Department of Health data released Thursday. But health officials, facing increasing challenges from parents, students and community members trying to conceal the spread of the virus to keep schools open and sports programs running, say those numbers are almost certainly an undercount.

Susan Klammer, an epidemiologist with the department, said in some communities, resistance to testing or quarantining after COVID-19 exposure has become more pronounced — and, in some cases, hostile — in the period since the Minnesota State High School League restarted school sports programs. Klammer said police have been called in cases where health workers were threatened for recommending that students quarantine, and students were threatened and harassed by their peers after seeking COVID-19 testing. Health officials have been notified of schools where groups of students have made pacts not to get tested, and to keep quiet if they think they are sick or have been exposed to the virus.

"It is incredible how the tenor has changed in the last couple of weeks," Klammer said.

The shift comes as the state is experiencing an uptick in COVID-19 cases and deaths. On Thursday, the Department of Health reported an additional 19 deaths and 1,169 positive cases. The death tally was the second-highest since mid-June, and brought the state's total count to 2,199 deaths.

Since Oct. 8, Minnesota has reported more than 1,000 new cases each day, bringing the total number of known infections to 117,106. Although some of that is the result of more testing, new case growth on Thursday slightly surpassed the growth in tests. Young adults represent the largest share of new cases, and public health officials are concerned that group will pass on the virus to people who are the most vulnerable to complications.

The spread of the virus across communities of all sizes has contributed to the growing number of school-related cases.

Since Aug. 1, the state has tracked 1,803 cases in which the person who tested positive spent time in a school building when they could have infected others. Students make up slightly more than half of that group, with teachers and school staff accounting for the remainder.

Just two counties — Cook and Kittson — now have low enough spread of the virus to meet the state's metrics for in-person learning for all students. And on the other end of the spectrum, nine counties had widespread enough virus activity for the state to recommend distance learning for all students: Chippewa, Kandiyohi, Lac qui Parle, Lyon, Martin, Murray, Pipestone, Waseca and Yellow Medicine.

The county virus data forms the basis of schools' decisions for how to operate, but it isn't set in stone; counties where high case numbers are tied to a specific facility or known outbreak might be able to stay open, for example. That's why a number of schools are operating in models different from those recommended for their county.

Klammer and Kris Ehresmann, the health department's infections disease director, said schools have seen cases spike along with community infections after big events like weddings and funerals. But they've also tied school cases to smaller social gatherings among students and school staff. In some cases, those infections have pushed school case counts up to levels that have prompted a move to hybrid or distance learning.

"If you've got a football team that has chosen to socialize together and you have transmission, that can easily get you to the number of cases that means that school has [to shift]," Ehresmann said.

Since school sports resumed earlier this fall, positive cases and quarantines among student athletes or rising cases in schools have forced the cancellation of football games for teams from Kasson-Mantorville, Montevideo and Fairmont, among others. Volleyball matches have been canceled for teams from Chisago Lakes and Rosemount.

Schools that have to shift to distance learning because of COVID-19 spread in the community are not allowed to hold practices or games.

Erich Martens, executive director of the Minnesota State High School League, said health officials have notified his organization about people attempting to avoid testing or quarantine to keep sports running, but he has not received other reports of that kind of activity. He said people should take health protocols seriously.

"We need everybody doing the very best they can to keep everybody safe," he said.

Dawn Gillman, a parent of two football players in the Dassel-Cokato school district, and the organizer of Let Them Play MN, a 20,000-member Facebook group that advocates for allowing students to play sports during the pandemic, said canceled games and sports seasons are devastating to students and families already under high levels of stress.

Gillman said she doesn't personally know of anyone who has avoided testing or quarantine to keep playing sports. But she also isn't surprised that there may be people trying to get around the system to preserve what's left of the fall sports season. She said the relatively low number of serious COVID-19 cases among children and teens, when compared to other age groups, makes some parents feel confident that students should be in school and playing sports.

"I'm guessing there might be people in Minnesota who would bypass [testing or quarantining], and I'm telling you it's likely because they don't want their school to get shut down," she said. "It's not even about sports as much as it is about togetherness and community."

Ehresmann said she understands why people want everything — school, sports, social lives — to go back to normal. But she said disruptions will continue for schools and sports so long as the virus continues to spread across communities.

"People think they would like to hide this or not have cases come to detection," she said, "but ultimately the nature and spread of transmission is such that if you have a match and you're trying to hide it in a pile of kindling, you won't do a very good job. Ultimately, you get a conflagration."

Staff writer Glenn Howatt contributed to this report.

Erin Golden • 612-673-4790