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Can your cellphone track coronavirus?

Mobile phone tracking could prevent spread of disease, but encourage government snooping

As public health workers race to stop the coronavirus, some in the technology field have developed a novel tool to tell how far the illness has spread: your cellphone.

Location tracking apps on cellphones are being used in China, Taiwan, South Korea, and Israel to slow the spread of COVID-19 by limiting contact with infected people. With data from several of the Asian countries suggesting this Draconian approach is helping, researchers in the United States are trying to develop versions that would work within the bounds of more restrictive privacy rules in this country.

A woman checked her cellphone while wearing a facemask in Los Angeles recently. FREDERIC J. BROWN/AFP via Getty Images

Ramesh Raskar, a professor at the Massachusetts Institute of Technology Media Lab, is building an app called PrivateKit that would warn users about close encounters with infected people, without jeopardizing the users’ anonymity, using location data cellphones already collect.


He hopes people who have tested positive for COVID-19 would voluntarily share their location data with public health officials, to help them identity hot spots and potential paths of infection. Healthy citizens could track their own movements, comparing their locations in PrivateKit against markers showing every time they came close to someone infected with COVID-19. The user could then decide whether to quarantine himself.

Unlike the technology used abroad, Raskar said this system would be voluntary, and only the user can decide whether to share his or her data. When fully operational, PrivateKit would only show infected people as a mark on a map. It provides no other data about them, to ensure that the system can’t be used to identify and harass victims of the disease.

Growing up in India, Raskar felt “a sense of community taking care of itself,” he said. "But in today’s world we have lost that agency and we feel manipulated.” He believes PrivateKit can protect the public while respecting the individual. “It doesn’t treat people like ants,” he said.


Other smartphone-based disease tracking programs have been far more ambitious. In South Korea, public health officials are able to gain access to anyone’s phone location data and combine it with their medical history and even financial records. Taiwan also has a law permitting the collection of location data during public health emergencies.

China requires citizens to share their locations, and those who’ve been to hot zones may be prevented from traveling or ordered to stay at home. If they go to a transit stop or other public place, they have to produce a mapping app on their phones that is color-coded to indicate whether they’ve been in a hot zone.

Last week , Israel launched a tracking system that gives health officials data on the movements of infected people, going back two weeks before they were diagnosed. This is compared against the location records of millions of Israelis. Any who have been in close proximity to an infected person gets a text message urging them to self-quarantine.

Taiwan also keeps tabs on high-risk individuals. For example, people known to have visited dangerous areas such as Wuhan in mainland China get text messages urging them to stay at home for a couple of weeks. And the authorities monitor the location data from their cell phones to make sure they comply.

But the Taiwanese have also used location tracking in less-intrusive ways. When a passenger from the cruise ship Diamond Princess tested positive for COVID-19 after docking there Jan. 31, officials obtained cellphone location data about everyone who debarked from the ship during its visit. The authorities didn’t reveal the identities of any passengers, or try to track down everyone who might have visited the same locations. Instead, they issued public warnings that people who’d been to the same locations might also be infected and should self-quarantine.


“They told the public, 'hey, these are the 50 places where they traveled.’ They didn’t tell people which person went where," said Jason Wang, director of the Center for Policy, Outcomes and Prevention at Stanford University. This, he said, gave everyone a timely warning without comprising any one person’s identity.

In the United States, President Trump’s aides have held talks with executives from Facebook, Google, and other firms to explore how technology could be used against the coronavirus. According to published reports, the discussion included how using anonymized location data could show people moving to and from known virus hotspots, and whether people are actually following government advice about “social distancing.”

More aggressive tracking of the kind used in other countries will probably run headfirst into the US Constitution.

“The government and the private sector must be very careful about plans to make use of cellphone information linked to particular customers” said Marc Rotenberg, president of the Electronic Privacy Information Center, an online civil liberties group. He noted the United States has strict laws protecting the privacy of cellphone records. And a 2018 Supreme Court ruling held that police agencies can’t get access to a criminal suspect’s location data without a search warrant.


Because it’s voluntary, PrivateKit should be legal. But would it work? Ryan Calo, a law professor at the University of Washington, predicted few people will use it voluntarily. With so little data to work with, “the error rate around this thing will be enormous," Calo said.

In addition, the app could give some users a false sense of security, causing them to relax their precautions against the virus because the app shows — perhaps wrongly — that they haven’t encountered anybody who’s ill.

The first version of PrivateKit is available in Google and Apple app stores, and Raskar said a more advanced version that will allow infected people to share their data with public health authorities is coming soon. He said his group is in negotiations with the World Health Organization in an effort to ensure that the app gets widely adopted.

Even so, Raskar argued that if just, say, 10 percent of Americans were to use it, that would be enough to significantly reduce exposure to the virus, since each COVID-19 positive person may infect more than one other person. If the app causes even a few people to avoid exposure to the disease, said Raskar, that would make a difference.

Raskar also said that no matter what the app shows, everyone should still practice strict hygiene and social distancing to avoid being infected.

Carlo Ratti, director of the Senseable City Lab at MIT, opposes the use of phone location tracking for commercial purposes. But, if location tracking can bring an end to the coronavirus plague, he’s willing to make an exception.


“In this case," said Ratti, "it’s being used for a good cause.”

Hiawatha Bray can be reached at Follow him @GlobeTechLab.