Posted on the walls of a nerve center inside the Minnesota Department of Health headquarters are dozens of sheets of paper identifying people who have tested positive for COVID-19.

For now, at least, there is still enough wall space to add more sheets with even more names of those who will fall ill as the pandemic spreads across the state.

But as case counts surge with more testing and the wall space fills up, there aren't enough investigators to keep up with the work, which involves a detailed interview with the infected individual and another round of calls to family members, friends and co-workers who may have been exposed.

Currently, 100 investigators are handling the cases. But it could eventually take at least 650 more to carry out the "trace and isolate" aspects of the state's containment strategy, according to Kris Ehresmann, infectious disease director at the Health Department.

Tracing and testing are seen as the two essential tools needed for any state to slow the virus and safely return to public life. Implementing one without the other could leave state residents facing an ongoing, unacceptable risk.

Although Minnesotans have been sending Ehresmann résumés and e-mails in hopes of being hired to do the work, the pandemic has restricted state spending.

"We currently have a hiring freeze at the state," Ehresmann said. "We are looking at reassigning staff from within the agency as well as staff within the state system."

The estimate of 750 case workers was based on a Massachusetts study, Ehresmann said, and it remains to be seen how quickly and how much Minnesota will need to ramp up staffing. Massachusetts is in the process of adding 1,000 contact tracers.

Under a plan announced last week, health care systems and the state's testing laboratory hope to run a combined 20,000 patient samples a day to look for COVID-19.

Since then, testing volume has steadily increased, with about 2,800 tests run on Friday, finding 261 more cases.

Currently, patients representing a new case are being contacted within 24 hours of a positive test result, Ehresmann said.

For many, the call from the state contact investigator is the first time they learn that they have fallen ill from a new coronavirus that was first detected five months ago.

"Nobody likes to hear that they have COVID," said Ehresmann. "You have to have empathy. This is a scary time for them."

How tracing works

As the liaison between patients and the health department, it's important that case workers have some public health experience because they need to answer questions about the disease, give advice and get information about where the person has been and who they have been in contact with.

"You want to make sure that you are picking up clues that people are giving," Ehresmann said. "We actually talk to them about what we need from them so there is nothing left to chance."

Each case gets logged into the department's computer tracking system, then gets posted on the repurposed conference room walls as a low-tech but convenient way of helping the investigators know who is handling what.

Once the initial "day zero" interview is done, red file folders containing case information are walked down the hall to contact tracers, whose job it is to call everyone who had close contact with the infected individual.

For now, all of the work is being done on-site at MDH headquarters in St. Paul with some distancing precautions. Eventually, more work will be done remotely as the ranks of investigators and tracers grow.

"A lot of times people are expecting our call," said Carly Baade, one of the agency employees who have been redeployed as contact tracers.

"We talk to them about their exposure and the monitoring of symptoms," said Baade, whose regular job is in the MDH's foodborne diseases unit.

People who have been in close contact with someone known to have tested positive are asked to quarantine themselves for up to two weeks, the estimated maximum incubation period of the virus that causes COVID-19.

By isolating people who are sick and people who might be sick, the goal is to prevent even more infections; research shows that one person transmits the virus to an average of four others.

"People have been pretty understanding," Baade said. "Because of the stay-at-home order we are really not asking a lot more of them. The biggest thing is not going to work."

Assessing risk

Each confirmed case results in follow-up calls to determine who has been exposed. While the number of calls varies depending on the case, the record so far for a case is 80 calls to people, most of them co-workers.

The department also has a team dedicated to calling health care workers who have been exposed to COVID-19 patients or residents.

"We interview them and assess their risk," said Sudha Setty, who at MDH typically works with clinics to help them improve their vaccination rates. "We tell them we are going to monitor their health by e-mail."

The daily e-mail contains a survey asking the health care workers about their symptoms, their body temperature and whether they have been asked to return to work.

If a worker doesn't respond within two days, MDH follows up with another call.

About 10% of the nearly 3,500 cases in the state have been among health care workers. Although some were infected outside of their workplaces, such as in travel, they still present a potential risk to patients or residents of hospitals, long-term care, treatment centers and other facilities.

In addition to the Health Department, some local public health agencies also are involved in the COVID-19 response.

To increase the chances that people will stay at home, the local agency contacts infected individuals to see if they need help.

"You will be in quarantine for the next 14 days. We need you to stay home, so let's talk about a plan," said Nora Moore, an epidemiologist with Ramsey County Public Health.

Many people rely on family or friends, but for others, the county can arrange for delivery of groceries, medications and other essentials, such as a thermometer.

"We are making sure that they are allowed to stay at home and be able to do that safely," Moore said.

Some local public health departments also might be enlisted to take on more of the case investigation work, Ehresmann said.

COVID-19 may be triggering an unprecedented public health response in terms of staff resources, but it follows the playbook that comes with any outbreak, including measles, chickenpox and tuberculosis.

Glenn Howatt • 612-673-7192

Twitter: @GlennHowatt