Minnesota has gone all-in on contact tracing — mobilizing more than 400 interviewers and investigators to find people at risk for COVID-19 and prevent them from spreading the infectious disease.

But a new report questions that strategy against the coronavirus causing this pandemic. And those concerns were raised irrespective of the mass protests over the death of George Floyd, which could produce a new wave of COVID-19 cases that would be tough to trace.

“We’ve almost seen a mind-set that if a little contact tracing is good, a lot more must be better. … We’re saying, ‘No that’s not true,’ ” Michael Osterholm, executive director of the University of Minnesota’s Center for Infectious Disease Research and Policy (CIDRAP), said on Tuesday.

CIDRAP’s report stated that contact tracing is valuable against viruses that infect a small percentage of a community, and cause clear symptoms, but that COVID-19 is widespread and involves a coronavirus that many people carry without symptoms.

The report recommends continued study to see if contact tracing works in the U.S. rather than assuming that it will work as well as it did in Asian countries with strict government testing mandates and quarantines.

Testing boosts tracing

The Minnesota Department of Health on Tuesday reported 25,508 lab-confirmed cases of COVID-19 and 1,072 deaths, but health officials suspect that as much as 5% of the state’s population has been infected. That would be 280,000 people.

Contact tracing usually occurs after people have been diagnosed through testing, and identifies anyone they have been close to who might have been infected. Those at-risk contacts are then asked to quarantine themselves until their infection status is clear.

The CIDRAP report raises valid concerns, though state infectious disease director Kris Ehresmann said that contact tracing isn’t expected to identify all cases and stop the virus’ spread completely.

“We can’t say that case investigations or contact tracing can eliminate transmission,” she said. “We’re really trying to mitigate as best we can.”

Contact tracing helped contain a measles outbreak in 2017 that was centered around Somali-Americans and child-care facilities. At the start of the COVID-19 pandemic this winter, Minnesota officials viewed it as part of a containment strategy to keep the virus from spreading out of control, and discussed how it could reach a point at which it would no longer be effective.

As the search for treatments and a vaccine continues, though, Ehresmann said contact tracing remains useful.

“It’s the tool that is available,” she said.

It could be working, too.

An increase in diagnostic testing over the past month has allowed for more contact tracing, and in the past week the growth in COVID-19 cases in Minnesota has ebbed. The 310 lab-confirmed cases on Tuesday was the lowest daily case count in the COVID-19 pandemic since April 27.

Hospitalization numbers have plateaued for now as well — at 537 COVID-19 patients admitted and 248 needing intensive care statewide. Those numbers had been rising so fast two weeks ago that hospitals in the Twin Cities were nearing capacity and diverting patients.

Ehresmann said her staff is keeping up with the goals of reaching out to people within 24 hours of positive tests, and having tracers conduct at least eight interviews per day. There is no way to know if that is reducing the number of COVID-19 cases, though.

As of May 24, 36% of people infected with COVID-19 in their communities had no known sources of exposure — preventing health officials from identifying others at risk.

Getting people to pick up their phones is one limitation, though Ehresmann said most comply with quarantine requests once they are determined to be at risk.

Adequate information is another limiting factor. About 10,000 free tests at National Guard armories over the Memorial Day weekend found 405 COVID-19 cases.

To keep up with higher-than-expected demand, the testers accepted forms from people without complete contact information. That has hindered contact tracing.

Reaching vulnerable groups

Ehresmann said it is premature to assume Minnesota has peaked in its COVID-19 cases — given the potential of the protests to spread the virus.

At a rally Monday night at the spot where Floyd died last week, about a third of the 1,000 attendees weren’t wearing masks.

The state on Tuesday advised doctors to test protesters, first responders and volunteers who cleaned up after the riots — regardless of whether they had symptoms of infection.

Ehresmann said the state is looking to improve contact tracing in vulnerable populations, including in minority and immigrant communities that have been hesitant to participate. The state has offered a $1.5 million contract to firms that can increase minority participation in COVID-19 testing and contact tracing this year.

Minorities have suffered higher rates of severe COVID-19, in part because they have more chronic health problems that complicate their infections. Black people make up less than 7% of the state’s population but more than 20% of its COVID-19 hospitalizations.

One concern with the focus on contact tracing is the distraction from other public health problems that haven’t gone away amid the pandemic.

Minnesota’s contact tracing team includes workers from other state health divisions who were reassigned, as well as volunteers and workers provided by health insurers — Blue Cross and Blue Shield of Minnesota and Medica.

Retasking foodborne disease investigators was easier with restaurants shut down, but they are starting to reopen, Ehresmann said.

Osterholm said that is a key problem if states commit too many people to contact tracing for COVID-19, without proof that it helps, and then neglect proven services.

The rate of childhood immunizations has dipped, for example, Osterholm said.

“I know that’s a very bad thing,” he said.

The state is seeking to outsource the case investigation and contact tracing work, in part to allow health workers to return to such tasks. It is seeking bids from firms that can manage up to 1,400 workers.

The state also hired Rose International, a St. Louis-based staffing firm, to hire about 40 contact investigators with specialized skills, including medical backgrounds and proficiency in foreign languages. The contract, which can pay out up to $3 million, runs until July 1.

Staff writer John Reinan contributed to this story.