Frieden notes that behind most of these apps are armies of traditional contact tracers, so it’s not clear—at least to him—that proximity tracing, as it’s called, even works. “You’ll read a lot of misguided stuff on Twitter and elsewhere about ‘This is what Asia did.’ It’s not true. China has done traditional contact tracing on 730,000 people. “

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In the US, Utah’s contact-tracing system makes the most extensive use of technology. In March, the state commissioned Twenty to build an app now called Healthy Together. It aims to more quickly connect contact tracers with people who are Covid-19 positive, and help the infected use their smartphones to build a one-week timeline of whom they’ve been with. “Once you have this app, it tracks where you go,” Governor Gary Herbert said in introducing the app. “If someone has COVID-19, it can go back and see who you’ve bumped into.”

Roughly 40,000 Utahns have downloaded the app, a little more than 1 percent of the state’s population. That’s a long way from the more than 60 percent adoption many epidemiologists think is necessary for contact-tracing apps to be effective. But it will be helpful no matter how many people use it, says Utah Health Department spokesperson Tom Hudachko. “Our app isn’t going to be sending automatic notifications to people, so it doesn’t matter to us what the saturation is.” He said information the app generates is sent to the state’s 1,200 contact tracers. They can then decide whether to call potentially infected people and urge them to be tested, or to warn a business that it’s hosted a person who tested positive.

Utah and app developer Twenty had hoped to use the Apple-Google technology to marry Bluetooth data about other nearby phones with location data showing where an infected person’s phone had been. But Apple and Google, sensitive to concerns that they aim to collect data themselves, said Monday they won’t allow apps built on their tech to do that.

The Apple-Google change may mean that contact-tracing apps like Citizen’s and Twenty’s will prove most useful in workplaces, to monitor contacts of infected employees. Twenty CEO Diesel Peltz and Citizen CEO Andrew Frame said they are fielding calls from employers interested in their contact-tracing technology. Corporate executives don’t have to worry about getting reelected, like politicians, and they can mandate employees do things—like download a contact-tracing app—that governments cannot.

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Nat Turner, CEO of Flatiron, a New York City-based health care technology company with 1,000 employees, said he was particularly taken by the sophistication of Citizen’s app, which is primarily used to track information about crimes. When Flatiron reopens its offices, Turner says he plans to check employees’ temperatures and may periodically test them for signs of the virus. “But there is no way you can virus-test employees every time they walk through the door. So mandating the use of a contact-tracing app like Citizen’s, for example, is probably going to be part of our toolbox,” he said. “If I could notify the 30 employees who were working in the same conference room that they were exposed to Covid-19, and I could know that through cell phone proximity data, that’s hugely valuable to me as an employer.”

Citizen, unlike many other technology players in the contact-tracing game, has another option: It has a big enough installed base in many cities—2 million in New York City, 1 million in Los Angeles—that it is considering turning on the contact-tracing functionality it’s already built, allow users to opt in, and see where it goes.

It’s riskier. If users freak out, if privacy advocates protest, or if city officials speak out against it, that could damage Citizen’s brand. But executives there have been trying for a month to get traction with states and cities—with little to show for it. If users like the contact-tracing functionality, it could create political cover for more cities and states to embrace it.

Frame, Citizen’s CEO, says the reception from cities and states has been frustrating and humbling. But like any Silicon Valley entrepreneur, he remains undeterred. “Government is clearly focused on manual contact tracing right now, which is the right first step,” he said. “We are committed to working with everyone to stand up an effective and safe system, however long it takes.”

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