In this Feb. 13, 2020, file photo, public health nurse Jennifer Morgan, right, checks-in via phone with a patient self-quarantined at home who had some risk of exposure to the coronavirus as University of Washington epidemiology student Erika Feutz observes at the public health agency for Seattle and King County. Washington state now has about 700 people focused on tracing contacts, with plans to expand the workforce to 1,500 by the second week of May. Credit: Elaine Thompson | AP

Click here for the latest coronavirus news, which the BDN has made free for the public. You can support our critical reporting on the coronavirus by purchasing a digital subscription or donating directly to the newsroom.

Editor’s note: This article was produced through a partnership between the Bangor Daily News and the Solutions Journalism Network, a national non-profit organization that supports rigorous journalism about solutions to problems.

The methodical interviewing of those who have the coronavirus or may have come into contact with it has given Maine important insights into how the infection has spread in the state, at one point narrowing the origin of a cluster of cases to a single traveling salesperson.

The process of contact tracing — interviewing a sick person to gain an understanding of how they became infected — will be more important than ever in the coming weeks, as the state embarks on a phased reopening process that began Friday. Case counts in the coming months and where they arise will play a direct role in how the reopening continues, public officials said this week.

[Our COVID-19 tracker contains the most recent information on Maine cases by county]

“If the Maine CDC detects any resurgence of the virus, we will move quickly to halt progression through the stages and reimplement restrictions to protect your health and safety,” Gov. Janet Mills said Tuesday in announcing the gradual reopening.

But many states may not have enough contact tracing manpower, a symptom of the public health spending cuts that the country has seen in the last decade. One public health expert called contact tracing epidemiology’s “basic tool” but said it would become ineffective if the virus becomes so widespread that it becomes impossible to trace.

Contact tracing gives us clues as to where the virus is coming from, but some say most states don’t have enough resources to do it correctly. Epidemiologists in Maine have said they try to get a sense of what happened from the period two days before people started exhibiting symptoms until they began to self-isolate to get a sense of everyone with whom they might have come into contact. The federal CDC says some spread of the virus can occur before symptoms appear, but people are thought to be most contagious when symptomatic.

The investigation can lead them to people’s employers or anyplace they may have visited. It can take some time for investigations to conclude as people remember more details about where they’ve been and the people with whom they’ve been in contact.

Maine Center for Disease Control Director Nirav Shah the process is critical, especially now because there is no coronavirus vaccine.

The state uses contact-tracing information to alert individuals of possible exposure and the public to potential outbreaks. Public health officials use the information to make recommendations on precautions people should take to keep from spreading the virus, such as quarantining — when a person who may not be sick self-isolates until symptoms appear or the potential for the illness is thought to have passed.

The National Association of County and City Health Officials recommends that states employ 15 contact tracing staffers per 100,000 people during normal times and double that number for that same population during a pandemic. Maine and the vast majority of states do not have the latter staffing level, NPR reported.

The type of contact tracing Maine needs as its economy reopens will be determined by where the virus spreads.

Pressure is mounting for more contact tracers. A recent study co-authored by the Johns Hopkins Center for Health Security and the Association of State and Territorial Health Officials called for an additional 100,000 tracers across the country to start. A bipartisan group of former health officials have called for $46 billion to be dedicated to tracing and other virus containment methods.

Maine currently has 30 employees dedicated to contact tracing on a full or part-time basis, Shah said Friday. How many more the agency hires depends on what the virus does. If the state continues its current trajectory — hospitalizations have declined and active cases are plateauing — he said the state will double its workforce.

But if the spread of the virus accelerates, Shah said the CDC would look to raise contact tracing staffing to 100.

Where the virus occurs will determine what kind of contact tracing is needed.

New cases are being driven largely by known outbreaks — such as those seen at long-term care facilities, a homeless shelter in Bangor and a poultry processing plant in Portland — rather than by community transmission of the virus. Investigating those outbreaks requires advanced training, Shah said, whereas investigating the community spread of the virus relies more on tracers following up and making recommendations to those affected.

Contact tracing is limited in its effectiveness without the testing and health infrastructure to support it. Dr. Peter Millard, a former CDC epidemiology staffer and adjunct professor with the University of New England, called contact tracing the “basic tool” of epidemiology. But it will not be as useful if the state becomes saturated with cases, he said.

“It loses effectiveness,” he said, “because there comes a point where there is too much community transmission that it becomes an impossible task.”

Only four counties — York, Cumberland, Androscoggin and Penobscot — have confirmed community transmission, in which the virus spreads among people who haven’t traveled to virus hotspots and haven’t been in contact with others known to have been infected.

It’s impossible to know for sure how widespread the virus is in Maine because testing has been largely limited to first responders, health care workers and vulnerable populations. Those who are asymptomatic may never end up getting tested and are likely spreading it unknowingly, he said.

Should the state increase its contact tracing, Millard said, the CDC needs to back it up with the ability to process the data. The state’s health care systems also need to be prepared for a possible surge in cases.

“We know we are going to have more cases,” Millard said. “The question is, how soon are they going to occur and can we react fast enough?”

Watch: Nirav Shah on tracing the origins of coronavirus cases in Maine

[bdnvideo id=”2962056″]