Stop the spread of COVID-19? Gov. Pritzker, there’s an app for that

A team led by a Massachusetts Institute of Technology technologist has developed a free digital contact tracing app. But it needs an assist from government to be most effective, and Illinois should lead the way

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An app for tracing contacts during a pandemic, devised by a team at the Massachusetts Institute of Technology, could prove to be a powerful help in controlling the spread of COVID-19, Ed Zotti writes

An app for tracing contacts during a pandemic, devised by a team at the Massachusetts Institute of Technology, could prove to be a powerful help in controlling the spread of COVID-19, Ed Zotti writes


Ramesh Raskar has a plan with a reasonable chance of controlling the COVID-19 pandemic. Everyone in Illinois can help make it happen. But Gov. J.B. Pritzker needs to make a call first.

Raskar, a former Google and Facebook technologist who holds nearly 100 patents, heads a team at the Massachusetts Institute of Technology that has developed a digital contact tracing app called PrivateKit: SafePaths. It’s available free from the iPhone and Android app stores.

Contact tracing is essential to stopping COVID-19. It’s one of what Pritzker calls the “three T’s” — testing, tracing and treatment. The head of the federal Centers for Disease Control and Prevention says we need to do it.

Traditional contact tracing is slow and tedious. When someone tests positive for a dangerous virus, you find out everyone they’ve been in contact with for as long as they’ve been contagious — in COVID-19’s case, at least 14 days.

Then, you track down those people, test them, quarantine the infected ones and trace their contacts. Once everyone with the disease has been identified and isolated, the pandemic stops.


Traditional contact tracing is practical only in the early days of an outbreak, when few people have been infected. In most of the United States, we’re long past that point.

If everyone cooperates with the stay-at-home order, though, and the COVID-19 caseload drops, eventually contact tracing becomes doable again.

Just one problem. Researchers at Oxford University have found that because COVID-19 is transmitted so easily — many with the disease are contagious for a week before they show symptoms, and some never get symptoms at all — contact tracing has to be almost instantaneous to do any good. If it takes days, that’s too late.

Digital technology using smartphones makes instant contact tracing possible. As I previously wrote, China and South Korea successfully used it to control the pandemic.

But the technology can be intrusive. In China, people must have software installed on their phones that tracks their every move — useful when you’re trying to stamp out a pandemic but also handy for controlling the masses.

South Korea isn’t that bad, but the emergency alerts it beams out when someone tests positive for the coronavirus sometimes go into creepy detail about the patient’s travels — reportedly including an overnight excursion to a “love motel.”

Ramesh Raskar.

Ramesh Raskar.

Dominick Reuter / MIT

The PrivateKit app that Raskar and his team have developed sidesteps such problems. It uses Bluetooth technology to record any close encounters you have with other PrivateKit users plus GPS location data to create a diary of your daily travels.

The diary is encrypted and lives only on your phone. If you test positive for COVID-19, you can — if you choose — turn your diary over to public health officials. They use software to scrub any details that identify you personally and load the result into a database.

Then they click on a button. An alert is sent instantly to every PrivateKit user with whom you came into contact in the past 14 days, telling them they could be at risk and providing instructions.

That’s it. No details about you.

Now suppose that before you tested positive you inadvertently came into contact with Jack, who hadn’t downloaded the PrivateKit app. The encounter wasn’t recorded in your diary, but your path was.

The day after you test positive, Jack downloads the app and has it check for COVID-19 contacts. The app searches the database, finds out Jack crossed paths with you and pops up an alert.

But wait, what if Jack never downloads the app or doesn’t even have a phone? If he comes down with COVID-19, how will health authorities know he got it from me?

They’ll figure it out the old-fashioned way with digital assistance. They’ll painstakingly ask Jack to recall his travels and load the information into the database. The software will do a search and, you’d hope, establish that Jack crossed paths with you.

It might not always work. But if mostly it does, and most COVID-19 carriers can be identified and isolated, the pandemic will peter out.

You’re thinking: This sounds like a long shot. Why bother?

Two reasons. One is to protect yourself. The other is to protect your family and friends.

At some point, stay-at-home restrictions will have to be eased, and people will start going back to work or school. Large gatherings will likely continue to be prohibited, but some semblance of normal activity must resume for the economy to start up again. And people will want to hang out, play sports, attend weddings, visit their elderly parents and generally get back to having a life.

Wouldn’t you want to protect those people? If you go to a party and later test positive for COVID-19, wouldn’t you want the attendees to know? If someone else at the party gets the disease, wouldn’t you want to be told?

That’s what PrivateKit does. If I go to any social gatherings or work meetings, I’ll want the app on my phone, and I’m not walking in unless everybody else has it, too.

Lots of people need to use the app to get the pandemic under control. Christophe Fraser, a co-author of the Oxford study, told me the adoption rate has be roughly 60%. Fat chance we’ll get the whole country to that level. It’ll be tough enough in Illinois.

So what? The app will help even if adoption is a lot less.

“Every life we save matters,” Raskar says. “I’d be happy to eliminate one case and prevent one elderly person from being exposed.”

None of this is possible without the support of local authorities. They need the software to enter the diaries of COVID-19 patients into the database, and medical personnel have to be trained in how to use it. An administrative infrastructure has to be set up to make the whole thing work.

A huge team isn’t needed. Raskar estimates it would take 300 people statewide, plus additional staff to do traditional contact tracing as a backup. He’s working with 20 jurisdictions around the country. He says Illinois could — and should — be the first to start.

Pritzker understands the importance of contact tracing. When I asked him at his briefing Thursday whether he was considering a contact tracing program, he responded enthusiastically.

Governor, please call Raskar and have him explain the technology and how it would be implemented. He’s got the best plan I’ve heard of for getting us past this nightmare.

Digital contact tracing worked in Asia. We can — and need — to do it here.

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