Contact Tracing 101: How It Works and What to Expect
Technology may play a role, but human contact tracers will likely be at the heart of the process
In the next few months, it’s going to happen to a whole lot of us: We’ll get a phone call from a number we don’t recognize, and on the other end of the line will be a person employed by a state or local health department to inform us we’ve been exposed to Covid-19. These calls, and any follow-up testing and subsequent check-ins, are part of the process of contact tracing, a public health strategy seen as critical to epidemic control.
Contact tracing is usually part of an effort to contain an epidemic in its early days and has historically been used to trace diseases spread by very close or intimate contact, like sexually transmitted infections, bacterial meningitis, and tuberculosis. But the experts creating the strategy for reopening American society think it will likely play an important role in guiding decisions after the coronavirus epidemic has crested.
“This is going to be what I would regard as a major experiment in modern public health for our country,” said Jeff Engel, MD, a senior adviser at the Council of State and Territorial Epidemiologists. “But it certainly makes sense epidemiologically and scientifically because if it’s done well, it works.”
Given how widespread the pandemic is, though, a disadvantage of contact tracing is its intense use of human resources. That’s why, on April 10, the Association of State and Territorial Health Officials (ASTHO) sent a letter to Congress recommending funding to expand the U.S.’s existing 2,200-person contact tracing apparatus into a 100,000-person workforce spread across the states. Even considering that some portion of that workforce would be made up of volunteers, ASTHO estimated that $3.6 billion would be needed to support this effort.
In an effort to reduce these costs, and to capitalize on the highly granular geolocation capacities of smartphones and other personal electronics, several public-private collaborations are exploring ways to shift some of the heaviest lifts of contact tracing onto the shoulders of tech. In May, Apple and Google plan to introduce an opt-in app using Bluetooth technology to alert users if they have had contact with an infected person, and Engel says he is being approached several times a week by vendors of new digital contact tracing tools.
“This is going to be what I would regard as a major experiment in modern public health for our country.”
If they’re designed with close attention to make public health work more efficiently rather than change how it works, tech-driven efforts could add great value to public health work during outbreaks, according to Paul Jarris, MD. Jarris is the chief medical advisor of Mitre, a nonprofit, federally funded research and development organization that has developed Sara Alert, an open-source tool for monitoring people at risk for Covid-19. In a YouTube presentation about the tool, Jarris says digital contact tracing’s advantage is that it allows public health to monitor people on “exception basis” — meaning that the need for human follow-up with an exposed person would be the exception in the process, not the rule.
If you get exposed to someone infected with Covid-19, your first encounter with a contact tracing system will likely look different depending on whether you’ve enrolled in a digital tool or not. If you’ve opted to use an app, says Engel, you’d be notified of your exposure by a text message or a robocall. (The identity of the case to whom you were exposed would be protected regardless of whether it’s an app or a person that makes the first contact with you, he says.) That notification would likely instruct you to call a toll-free number connecting you with a human contact tracer at your local or state health department.
Your initial interaction with that person would focus on educating you about what the exposure might mean for you and would also include an interview about your symptoms and a recommendation to self-quarantine for 14 days. Depending on your jurisdiction’s testing availability and guidelines, your contact tracer may offer you a test for the virus, and if you report certain symptoms, you may be connected with a health care provider for further evaluation.
For the next two weeks, the app would ask you to perform a self-assessment once a day. This would include a request to measure and enter your temperature and report symptoms like cough and shortness of breath. Your self-assessments would be forwarded to your local public health officials, who would reach out to you if your report suggests you need additional evaluation or intervention.
If you haven’t opted in to an app, all of these interactions — not just the initial one — would involve a conversation with a contact tracer employed by your local or state health department. Although these contacts might be more resource-intensive for public health, they can be a great source of comfort to the people at the other end of the line.
Although Covid-19 infection rates have not yet crested everywhere in the U.S., states are beginning to hire contact tracers. Massachusetts, which partnered with the nonprofit Partners in Health to hire 1,000 contact tracers, is several weeks into the process of contact tracing, and other states will be watching its experience closely as they design their own programs.
Also watching will be those concerned about privacy and the idea that increased government surveillance in the name of public health could be used to punish people for violating quarantine or otherwise infringe on the civil liberties of Americans, especially people of color and immigrants. In his presentation, Jarris notes that while local public health authorities would have the contact information of people monitored through contact tracing efforts, federal authorities would not have access to that identifying information.
“Geolocation is already hardwired into all of our phones,” says Engel, but would we use it in such a way? He suspects not. And as the experiences of several southeast Asian countries have shown, tech should not be seen as a silver bullet for this pandemic but as just one tool in a much broader public health policy toolkit. “Most of this is going to be through public education, personal contact — like a call or an app — and the goodwill of the people to voluntarily comply.”