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As Vermont reports a slowdown in the number of new Covid-19 cases, officials say the Department of Health will have 48 people by the end of the week tracking down individuals who may have been exposed to the novel coronavirus.
Public health experts say the epidemiological detective work known as contact tracing can help slow the spread in places like Vermont that have lower case counts. And it will play a key role nationwide as states ponder when to safely start lifting social distancing measures, with CDC director Robert Redfield saying last week that “very aggressive” contact tracing would be needed to prevent new outbreaks.
Health Commissioner Mark Levine said earlier this week that, even as Vermont considers measures like serological testing to determine who could be immune to the virus, the focus “at this stage of the virus” remains on containment.
“If in the general population cases keep appearing of coronavirus, we do want to know that, we do want to isolate, we do want to contact trace and quarantine as appropriate,” Levine said on Monday.
In the month since Gov. Phil Scott declared a state of emergency to limit the spread of the virus, the Vermont Department of Health has gone from having two to 48 people tracking who might have been exposed to someone who tested positive for Covid-19.
Unlike in coronavirus hotspots where the number of new cases outpaced local health departments’ abilities to do time-consuming contact tracing, Vermont has few enough Covid-19 cases — 768 confirmed cases as of Thursday — that the state can do contact tracing for almost everyone who tests positive.
“Sometimes there’s individuals that have no further contact information, unfortunately … but our pursuit has been 100%,” said Daniel Daltry, program chief of the HIV, STD and Hepatitis C program for the state health department. The department has pulled in people from the drug and alcohol and environmental health divisions, as well as district nurses, to ramp up health surveillance capacity.
When someone tests positive for Covid-19 in Vermont, a DOH contact tracer will first reach out to that person’s doctor to go over the patient’s history and strategies to prevent exposure to health care professionals. The contact tracer will then call the patient, first going over how they’re feeling before asking about the onset of their symptoms and who else they might have exposed.
“It’s not about everyone that you’ve seen over the past three months, the window is far shorter than that, but we can’t begin to appropriately look at … who should be interviewed until we understand how this infection has impacted an individual,” Daltry explained.
The aim is to suss out everyone who the infected person had prolonged enough contact with in the 48 hours before the onset of symptoms to put them at “medium to high risk” for contracting Covid-19, he said. Daltry said the department bases that risk assessment off CDC guidelines, adding that “you really have to sit down and talk with somebody to find out the particulars of the exchange or situation.”
Health department contact tracers will then call those potentially infected individuals to coach them on what to look out for, how to isolate, and how to get tested if they develop symptoms.
Daltry said the department continually evaluates whether they have adequate staff to conduct contact tracing, with the goal of interviewing people within 24 hours of their positive Covid-19 test result coming back. The health surveillance division is also in regular contact with the outbreaks team.
He stressed that Vermont’s contact tracing efforts fit within the broader context of statewide measures, like the stay at home order, taken to slow the spread of the virus. “I feel like we are hitting a broad swath of individuals, from our messaging alongside roads to the work that’s being done in places such as supermarkets and drugstores.”
Jimmy Young, 27, started developing symptoms of Covid-19 in mid-March, shortly after coming back from a work conference in Rhode Island.
“I had crazy body aches and probably had a fever — I didn’t have a thermometer, everywhere was sold out,” said the Winooski resident in an interview this week.
Young, who said he was “a bit worried” about the risk posed to him in contracting Covid-19 as an asthmatic, called his primary care doctor. After a Zoom appointment, his doctor’s office sent him to be tested at the Champlain Valley Expo in Essex.
Although Young had been told his test results would come back within 72 hours, it took five days for his results to come back. He waited that morning for a Department of Health follow-up call that his doctor said was coming, but decided after a few hours to call up the infectious disease epidemiology division.
Young spoke with the contact tracer for about an hour, mainly about what he should do to take care of himself and how long he should isolate for. They also went over where he had been in the past month, which included going to a conference in Rhode Island earlier that month and working the Saturday before he started feeling sick at the Burlington bar Three Needs.
“She wanted to go over tracing a bit, but at the same time, she was like ‘there’s so many people that have this right now to trace back to everyone (at places) where you’d been is difficult,” he recalled. The contact tracer recommended he reach out to people he’d recently been around at work, which he did.
“I would assume most other people are doing that too,” Young said of his efforts to reach out to coworkers. “You would hope so, at least.”
The governors of Massachusetts and Utah announced efforts earlier this month to deploy 1,000 contact tracers each to ramp up their contact tracing efforts. In Massachusetts, that figure is in addition to the 1,700 volunteers who’ve signed up to assist with contact tracing.
Scott and Levine believed Vermont and Massachusetts had an equivalent number of tracers, but appeared to have based that on incorrect population figures.
Vermont would have to increase multi-fold the amount of tracers to have the same number per capita as Massachusetts, though Massachusetts has three times as many positive Covid-19 cases per capita as Vermont.
“We’ve taken some incredible steps here early on to try and cross-train in order to do as much contact tracing as possible,” said Scott on Monday. The Vermont Department of Health has a list of 40 law enforcement officers from around the state who can help with their coronavirus response efforts; around 10 have been drawn on so far to help with travel monitoring and outbreak response, said Vermont State Police spokesperson Adam Silverman earlier this week.
Contact tracing could prove to be especially important for controlling Covid-19 based on preliminary research into how the virus is transmitted, said Laurent Hébert-Dufresne, an associate professor of computer sciences at the University of Vermont who specializes in complexity research in sociology and epidemiology.
“It seems to be driven quite a bit by super spreading events, which means it’s actually easier to control than you would believe based on classic (epidemiology) models,” said Hébert-Dufresne, contrasting it with the seasonal flu. “We try and fight it every year, and sometimes win that fight and sometimes lose it.”
He added that the “general lockdown” in the U.S. was wise given the spread of the coronavirus and the initial uncertainty around basics like transmission rates.
“But I’m a big fan of the idea of relaxing the lockdown progressively and as you do so, you need to be making sure that you’re using contact tracing protocols to see how much more at risk you’re putting people by relaxing a lockdown,” said Hébert-Dufresne.
Dr. Janet Baseman, an epidemiologist who is the associate dean at the University of Washington School of Public Health, said that effective contact tracing depends on adequate testing for Covid-19 — something the U.S. has struggled with to date.
“So there is a direct connection between the need for testing capacity and the need for those next steps of case investigation … because testing is the standard we’re using right now to confirm that somebody has a positive case,” she said.
Dr. Joshua White, chief medical officer at Gifford Medical Center in Randolph, said that ideally, the U.S. would track down everyone who’s been in contact with someone who tested positive for Covid-19 and get them tested to “put an end to any sort of chain of transmission.”
“On the other hand, here in Vermont, we have done exceptionally well at flattening the curve,” he said. “And it’s probably to some degree a little bit irrelevant, at least right at this moment.”
White added that contact tracing would be critical for Vermont to quash outbreaks that will inevitably pop up until a vaccine is developed.
Vermont has had multiple Covid-19 outbreaks at nursing homes and rehab centers, and there have been concerns raised about testing protocol and follow-up when those outbreaks were discovered. Daltry said the health department has elevated contact tracing efforts for those facilities, with his staff reaching out to the long-term care facility team if they discover that someone who tested positive for Covid-19 was recently released from a group home.
“We try to make sure we’re working with that agency on a plan that works best for them and their population,” he said.
Countries like South Korea and Taiwan that have been able to limit the spread of the virus have used data-collecting technology for everything from alerting people if they’ve been within a certain radius of an infected individual to keeping tabs on people in quarantine.
“At scale, mobile apps … and mobility data are super valuable,” said Hebert-Dufresne, who noted that contact tracing interviews provide a more in-depth look into potential exposure. “But I think that there is in both the data science community and the epidemiology community … a real consciousness right now about the tradeoff between the quality of intervention and the human rights cost of that intervention.”
MIT recently developed an app that collects users’ location data to determine if they’ve crossed paths with an individual who tested positive for Covid-19; Apple and Google announced last week that they are partnering on a similar effort. Developers of both say they’re seeking to strike a balance providing useful information with protecting users’ privacy.
For now, those tools are not something Vermont Health Department officials are looking into.
“I really don’t know enough about how that would be a tool to be leveraged here,” said Daltry of the contact tracing partnership between Google and Apple. “So I can’t say I’m in favor or opposed.
