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At least one data point suggests social distancing is having its intended effect in Minnesota

A smart thermometer startup’s data for Hennepin County shows fevers falling below what would be expected for this time of year.

A San Francisco smart thermometer company says its data suggest social distancing policies enacted to slow the spread of COVID-19 are working.

“Restrictions are Slowing Coronavirus Infections, New Data Suggest,” the headline on a widely circulated story in the New York Times that cited data from Kinsa, a manufacturer of smart thermometers.

Kinsa found that after spiking to atypical levels in the middle of March, the share of the U.S. population with a fever has dropped in the last week and a half. That might mean social distancing measures are reducing the share of Americans who are sick.

Policymakers in Minnesota say social distancing policies enacted in recent weeks will slow the spread of COVID-19. Data from Kinsa’s smart thermometers seems to back that up.

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Smart thermometers

Kinsa’s thermometers take people’s temperatures and send them, along with location data, back to the company, where it is anonymized and combined at broader geographic levels.

“We are able to aggregate an illness signal, essentially,” said Nita Nehru, the company’s  director of communications and partnerships. “It’s where and when are fevers starting and spreading across the U.S. to help give us a sense of where something unusual might be happening so public health first responders can target those areas before an outbreak becomes an epidemic.”

Kinsa has more than a million thermometers across the U.S. Since COVID-19 hit the U.S., the company has been getting as many as 162,000 temperature readings daily.

Public health officials have praised Kinsa’s data for being able to track spikes in fevers quickly. In past flu seasons, the company’s data has tracked closely to the Centers for Disease Control’s, but is collected in real-time versus being reported through health care providers.

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To check for atypical illness levels, Kinsa measures the share of illness in a given geography against a baseline level it developed with the help of Benjamin Dalziel, a professor at Oregon State University who studies infectious disease.

“You can call it an illness signature of a geography. So in particular geographies, illness — like flu, for example — will behave in a particular way,” that often differs from place to place, Nehru said.

“So what we were able to do was look at the illness signature of geographies across the U.S. and come up with a forecast,” she said — a prediction of what illness would look like at any given time based on typical behavior.

If fevers are above the expected level for a given point in time, Kinsa calls it atypical illness.

Kinsa’s “Health Weather” map of the U.S. shows atypical levels of illness in several current COVID-19 hotpsots, including New York and parts of Florida. Nowhere in Minnesota currently has atypical illness, as measured by Kinsa. (That doesn’t mean COVID-19 isn’t here. It certainly is.)

If fevers are below expected levels, that suggests something is causing less disease overall than is expected for a given time of the year. That may mean social distancing measures are working — not just to slow the spread of COVID-19, but also other diseases.

Fevers falling

The U.S. saw a spike in atypical illness — denoted in red in the chart above — in the second week of March. Illness levels dropped back to typical levels, then below them, in the third week of March.

New York, so hard-hit by coronavirus that hospitals are using refrigerated trailers in place of morgues because of the surge in deaths, saw a spike of atypical illness beginning the first week of March. That spike peaked around around St. Patrick’s Day, then started dropping, especially after New York Gov. Andrew Cuomo’s Stay-at-Home’ order went into place on March 20.

While Kinsa’s data doesn’t prove social distancing measures are the cause of the drops in fevers, they make a strong case that the two are related, Nehru said.

In Minnesota’s most populous county, Hennepin, the level of illness has not veered into atypical territory, but it has been below what Kinsa would expect since early March. The share of illness in the county leveled off a bit mid-March and declined again around March 19 — two days after Gov. Tim Walz’s executive order closing bars, restaurants and other places of amusement took effect. (You can look up Kinsa’s data on any county in the Lower 48 here).

Having data like this is important because it shows people the sacrifices they’re making aren’t all for naught, Nehru said.

“People are very inconvenienced and, for some people, it’s very hard, very lonely,” Nehru said. “The key takeaway is that it’s working, the sacrifices are working.”

What can Kinsa’s smart thermometers say about our future with COVID-19?

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It’s not a predictive technology, but Nehru said we’d expect illness levels to stay low as people practice social distancing.

“I think the question that we’re all going to be grappling with is when social distancing starts to let up which has to happen at some point, are illness levels going to spike back up again or will we be able to find a balance?”