In 2016, a case of measles popped up in the Denver metro area — just one case.

Health officials across five different organizations jumped on it, sending out workers to learn more about the patient and where he had been. Then they reached out to all the people who had interacted with him and figured out whether they contracted the virus. By the time the officials were done, they had interviewed 311 contacts of the patient and invested more than 750 hours. The investigation of that single case cost nearly $50,000.

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Now confronting the new coronavirus, Colorado is faced with implementing that kind of system — known as contact-tracing — on a massive and unprecedented scale.

Dr. Rachel Herlihy, the state epidemiologist, said the goal is to be able to track and investigate 500 cases a day statewide. To reach that mark, public health agencies across Colorado are currently hiring dozens of new workers and drafting existing ones into an army of shoe-leather epidemiologists fighting COVID-19, the disease caused by the coronavirus.

That army, combined with expanded testing, are at the heart of Colorado’s plan to contain the disease once the statewide stay-at-home order lifts next week. By doing a better job of tracking individual cases, the thinking goes, the state can be more targeted in whom it orders into quarantine — allowing everybody else to return to a slightly more normal life.

“Testing only has this epidemiological benefit when you couple it with the tracing and the quarantines that go along with it,” Gov. Jared Polis said at a news conference Monday where he announced plans for the state’s new phase of coronavirus containment, which he dubbed “safer at home.”

Colorado Department of Public Health and Environment Executive Director Jill Hunsaker Ryan speaks at a news conference on COVID-19, the coronavirus, on March 3, 2020. (Jesse Paul, The Colorado Sun)

Significant challenges

Pulling off this enormous contact-tracing initiative, though, comes with significant challenges to which there are not easy solutions.

Thorough testing is needed to give the army its marching orders. But Jill Hunsaker Ryan, the executive director of the Colorado Department of Public Health and Environment, said Monday that testing remains limited by supply chain issues. The state is getting testing equipment, she said, “but it’s not on any level that is predictable.”

“Testing is not widely available in any state, and it’s definitely not to the point where you can have an effective epidemiological response in any state,” she said.

Having enough people to do the work is another challenge.

Both CDPHE and county public health departments already have epidemiologists and others on staff who do contact-tracing work as part of their everyday jobs — battling diseases like tuberculosis or mumps.

“This is a common public health tool that’s been used for decades if not centuries,” said Dr. Lisa Miller, an epidemiology professor at the Colorado School of Public Health and a former top leader at CDPHE.

But scaling up to tackle a disease as fast-moving and widespread as COVID-19, Miller said, “That’s something we haven’t done before.”

Massachusetts recently announced a plan to hire 1,000 new contact-tracers. A report published earlier this month by The Johns Hopkins Center for Health Security and the Association of State and Territorial Health Officials estimated that, if Massachusetts’ model was scaled up nationwide, the country would need an additional 50,000 contact-tracers.

“However, it is likely that many more will be necessary, considering the large number of cases already in the United States, that COVID-19 has been circulating widely for many weeks and that we still do not have sufficient levels of testing,” the report argued. Its author recommended the nation enlist 100,000 new contact-tracers.

State epidemiologist Dr. Rachel Herlihy speaks at a news conference on COVID-19, the coronavirus, on March 3, 2020. (Jesse Paul, The Colorado Sun)

Herlihy said CDPHE is looking to hire 50 new contact-tracers. She hopes to have 25 of those hired by the end of the month. Epidemiology students at the Colorado School of Public Health will make up some of the new hires — the state has signed a contract with the school to bring in 20 students to do contact-tracing, Miller said.

Local public health agencies are also bolstering their contact-tracing corps, though mostly by reassigning people from within their agencies. Denver’s public health department expects to need as many as 50 new investigators; Boulder has plans to expand its investigation team to 26 from three.

Tri-County Health Department has an investigation team of 40, which the agency expects to expand “several fold.”

“For sure there will be a lot of training we provide for staff assuming these roles,” Dr. Bernadette Albanese, an epidemiologist at Tri-County Health, wrote in an email.

Ryan said she has also heard that the federal government might offer trained epidemiologists to assist states’ efforts.

“That would be a gigantic help,” she said. “But I haven’t heard any more than that.”

Science and art

Conducting contact-tracing is as much art as it is science. The work primarily involves interviewing — walking patients through their memories to understand more about where they contracted a disease and whom they may have had contact with.

Miller said there is generally a standard set of questions. The state’s manual for investigating cases of measles, for instance, tells health workers to ask about the family members or roommates they live with; the stores, restaurants, workplaces and health care facilities they visited; the modes of transportation they used; the public gatherings or religious services they attended; and the friends they hung out with.

Once they’ve built the timeline, investigators then get to work notifying and interviewing all those who came into contact with the patient. Investigators ask about any symptoms those contacts may be showing. They refer those showing signs of an infection for testing. And then, if the test results come back positive, the investigative chain continues.

Miller said much of this work can be done over the phone. They’re not always easy interviews, though. People may be difficult to find or reluctant to share information about their health. They may be grieving the loss of a loved one. Or they may be wary of being ordered to quarantine.

But Miller said the heightened attention to public health during the pandemic might also make some of these conversations less of a surprise.

“It’s great to see more people understanding what public health does and what these terms mean,” she said.

David Storey processes samples for COVID-19 test at Colorado Department of Public Health and Environment Laboratory Services Division in Denver, Colorado on March 14, 2020. (Pool photo by Hyoung Chang, The Denver Post)

New technology

To make the system less labor-intensive, Herlihy said the state is developing technology that can do a lot of the legwork — essentially an epidemiology app.

As she described it, the program wouldn’t track people’s movements. But a questionnaire in the app could take the place of an initial phone interview with a contact-tracer. The app could be used to help people find a nearby testing site or provide instructions on how long they must stay quarantined. And Herlihy said the app could also help public health agencies make sure people who are in isolation can get groceries or medicine delivered to them.

Colorado has also launched an online symptom checker for COVID-19. People who use the tool and enter their contact information can be given advice on whether to seek medical care and where to go.

But Ryan said the state hopes that the symptom checker can also be part of an early warning system. Combined with information from contact-tracing and reports on new cases and hospitalizations, the data will help health officials determine whether Colorado is succeeding in keeping the virus contained during this next phase.

“If we start to see metrics that we’re uncomfortable with,” she said, “we’ll know that a higher level of social distancing is indicated.”

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