Contact Tracing Helps To Slow the Spread of COVID-19—Here’s How It Works

Google and Apple announced in April a joint effort to help with COVID-19 contact tracing. They developed a solution that uses Bluetooth technology to help governments and health agencies reduce the spread of the coronavirus while protecting users' privacy and security. Virginia is the first state to implement the technology with a free new app called COVIDWISE, available from Apple and Android app stores as of Wednesday, August 5.

CDC Director Robert Redfield told NPR that the country needs to implement “very aggressive” contact tracing of those who test positive for the virus. So what is contact tracing and how does is help slow the spread of disease?

Experts In This Article
  • Jennifer Horney, PhD, epidemiology professor and founding director of the epidemiology program at the University of Delaware

Contact tracing is a way for epidemiologists to investigate outbreaks and communicable diseases, explains Jennifer Horney, PhD, MPH, an epidemiology professor and founding director of the epidemiology program at the University of Delaware. While this new app uses Bluetooth for tracing, states and local governments also employ contact tracers to do this work through phone calls.

Note that contact tracers are employees of health departments and will never ask you for payment. Scams have begun poping in which people posing as contact tracers try to get bank and credit card information from people. "That is absolutely not part of the process," Crystal Watson, a senior scholar at the Johns Hopkins Center for Health Security, tells NPR. "No one should give bank information or credit card information."

The process involves reaching out to those who were in contact with a person who has tested positive for a virus, like COVID-19.

"Because this is a novel disease, these types of non-pharmaceutical interventions are really the only way we have to fight the spread of COVID-19," says Dr. Horney. "We don't have medications or vaccines yet that we can use. All we can do is test people. When they're positive, we isolate them, and then we trace any contacts that they've had to see if those people should be tested." Contact tracing can also ensure that people who were exposed but aren't showing symptoms are self-isolating, she says.

"There are many privacy concerns that could be pointed out, but from a public health perspective, it's an amazing tool." —Jennifer Horney, PhD, MPH

According to a press release, the Google-Apple collaboration will allow Android and iOS devices to exchange information using apps from public health authorities. (The official apps will be available for users to download as early as May.) In the coming months, Apple and Google will work to enable a broader Bluetooth-based contact tracing platform that would allow more individuals to opt-in and enable interaction with government health authorities. Here's how it works: After confirmation of infection, people input their health information into the app, at which point the app sends an alert to other devices belonging to people who had recently come into close proximity of the infected person, reports the New York Times. A similar approach utilizing contact tracing was taken in Singapore, which experienced early success controlling the spread of the virus, says Dr. Horney.

"There are many privacy concerns that could be pointed out, but from a public health perspective, it's an amazing tool," says Dr. Horney. "We have 250,000 fewer federal, state, and local public health employees than we actually need. We can close some of that gap with technology in the short term. And then hopefully, in the longer term, think about how to staff up public health in the way that it needs to be able to adequately respond to pandemics."

Four specific things need to happen before social-distancing guidelines are relaxed, explains Dr. Horney: The country needs to see a sustained decrease in the number of new cases for several weeks; health care providers need to have access to appropriate personal protective equipment (including but not limited to N95 masks); testing needs to meet demand; and contact tracing needs to be implemented, she says.

"Hopefully, we'll have rapid testing as well as antibody testing, so we'll know who's already been infected and recovered, as well as contact tracing that's very effective," she says. "The point is to catch those cases early, isolate the people who are ill, and quarantine their contacts until we can ascertain whether or not they've been infected."

Originally published April 10, 2020; last updated August 6, 2020.

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