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

Keren Landman, MD
Elemental
Published in
5 min readApr 29, 2020

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Photo: Catherine Lai/Getty Images

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…

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Keren Landman, MD
Elemental

Infectious disease doctor | Epidemiologist | Journalist | Health disparities, HIV/STDs, LGBTQ care, et al. | kerenlandman.com.