Unknown infection sources key to COVID-19 future in Minnesota

After five days in Bethesda Hospital, Ronald Buhrt returned to his apartment and wife in Cottage Grove — fully recovered from his COVID-19 respiratory illness, but with a nagging question.

How the heck did he get infected?

"I have no idea, " said Buhrt, 79. "I had shopped some for food and I had been at the drugstore a few times, but basically I wasn't out all that much."

Solving such mystery infections could be a key to Minnesota's battle with the COVID-19 pandemic, especially as Gov. Tim Walz and state leaders dial back social distancing mandates and rely more on contact tracing investigations to identify outbreaks in families, communities and businesses before they spread.

A new state "dial back" dashboard showed Friday that 36% of COVID-19 cases involved people with unknown infection sources in their communities. That is higher than the state goal of 30%, and health officials said a continued rate above that could be grounds for new restrictions to reduce the spread of the coronavirus that causes COVID-19.

Whether 30% is the appropriate threshold, the state must do a better job at identifying the sources of COVID-19 infections so that it can spot developing outbreaks and protect others at risk, said Dr. Ruth Lynfield, state epidemiologist.

"When we come across cases that don't have a contact, it tells us that the virus is circulating and that it means perhaps there is a higher level" of cases than is known, she said.

"We are just trying to figure out what is going on here now that people are observing this," Lynfield said.

Some of these pediatric cases have occurred weeks after children suffered infections with the COVID-19 virus. Most children recover, but some of the cases mimic toxic shock syndrome and can cause rashes, digestion issues and problems with multiple organs, Lynfield said.

Whether there is a link to COVID-19 is unclear. So far, the pandemic has been harsher on the elderly and people with underlying health problems — who make up around 98% of the 683 deaths related to COVID-19 in Minnesota so far.

The state on Friday also reported a single-day record of 808 lab-confirmed COVID-19 cases, bringing the known case total to 14,240. Only 939 lab-confirmed cases involved Minnesotans 19 or younger. The youngest death so far has been someone who was 30.

In cases in which an exposure has been determined, living in long-term care remains the most likely cause of infection. That was the exposure source for 2,659 cases.

"When we hear about someone who says, 'I don't know, I just went to the grocery store and I don't know of any other exposure,' that's significant," said Kris Ehresmann, state infectious disease director.

Modeling by state health and University of Minnesota researchers assumed as many as 41% of COVID-19 cases are asymptomatic and people might be spreading the virus without knowing it.

As a result, the latest modeling this week predicted 1,441 deaths by the end of May under a scenario by which the statewide stay-at-home order ended on Monday. The modeling also predicted a surge of cases by June 29 because of the decline in restrictions and the increase in face-to-face disease transmission that could use up the state's supply of hospital intensive care beds and ventilators.

Walz said Minnesotans must remain cautious now that he is ending the stay-at-home order and replacing it with a new "Stay Safe MN" strategy that allows most retailers to reopen Monday with social distancing plans in place.

Group gatherings of no more than 10 people will be permitted as well. Bars, restaurants and hair salons and other service businesses will remain closed until at least June 1.

Buhrt said he was scared when his congestion and breathing got so bad that he needed hospital care. His wife tested positive as well, but she didn't have such severe symptoms. Neither had been out in the community much and had only visited their nearby daughter and grandkids through a car window.

Buhrt had taken to pacing up and down the halls of his apartment complex for exercise. Now back at home from the hospital and under isolation restrictions, he has taken to pacing from the living room to his front door.

A pitcher for the University of Minnesota in the 1960s, Buhrt said his fitness probably helped him weather his illness. He's resigned to never knowing how he got infected.

"It's a mystery," he said.

State health officials are hoping to solve more such mysteries with an infusion of additional contact investigators to rapidly reach out to people who test positive for COVID-19.

"We do want to bring that measure down" below 30% of cases with unknown transmission, Lynfield said. "We want to be able to control transmission within the community."

Additional funding for even more interviewers — who may be needed if case numbers surge — is unclear. House lawmakers have advanced a $300 million hiring plan, but a comparable state Senate bill includes only $5 million.

Walz on Friday said he was "a little nervous" that legislative support for this funding and the need for contact tracing was weakening, though he added that he ultimately has authority to earmark funds for that purpose while he still has peacetime emergency powers.

Investigators continue to use a federal threshold that people are at medium risk for infection if they spend 15 minutes within 6 feet of someone carrying the virus, Ehresmann said. However, state interviewers are asked to use judgment.

"If someone with COVID coughs in your face, then the 15 minutes doesn't matter," she said.