Wearable tech can spot coronavirus symptoms before you even realize you’re sick. Here’s how.

Data from a wearable device can reveal coronavirus symptoms days before you even realize you’re sick, researchers have found in preliminary studies.

That means fitness trackers could be on their way to becoming sickness trackers.

The initial findings from two academic studies are a small step in the fight against the coronavirus, and a giant leap for wearable tech. If Fitbits, Apple Watches and Oura smart rings prove to be an effective early-warning system, they could help reopen communities and workplaces – and evolve from consumer tech novelties into health essentials.

Since March, a half-dozen academic studies have been exploring whether the constant stream of data that wearables gather about our bodies offers any clue about who has caught the coronavirus. I’ve been a guinea pig for two of them, though I prefer the term “citizen scientist.” (See below for how you can contribute to studies still recruiting volunteers.) For now, these aren’t clinical trials – rather, researchers are gathering data and looking at it retrospectively for patterns.

The greatest potential might come from a lesser-known wearable I’ve been testing for the past five weeks: a health-tracking ring called Oura. The $300 wireless device looks like jewelry and collects data about my heart rate, breathing and – critically, for the coronavirus – temperature. The ring, made by a seven-year-old company based in Finland and the United States, is being used in two studies at West Virginia University and the University of California, San Francisco involving tens of thousands of health-care workers, first responders and volunteers like me.

I also joined a Scripps Research study with a $400 Apple Watch, sending data to researchers exploring whether heart measurements from a range of popular trackers are enough to detect the coronavirus or other viral infections.

None of the studies have yet published peer-reviewed results, but we’re getting the first evidence that the idea works. On Thursday, researchers at WVU’s Rockefeller Neuroscience Institute reported that Oura ring data, combined with an app to measure cognition and other symptoms, can predict up to three days in advance when people will register a fever, coughing or shortness of breath. It can even predict someone’s exact temperature, like a weather forecast for the body.

Professor Ali Rezai, the institute’s director, said the technology is valuable because it’s tuned to reveal infection early on, when patients are highly contagious but don’t know it. He calls the combination of the smart ring and app a kind of “digital PPE,” or personal protective equipment. It can say, “This individual needs to stay home and not come in and infect others.”

There’s more: Researchers at Stanford University studying changes in heart rate from Fitbits tell me they’ve been able to detect the coronavirus before or at the time of diagnosis in 11 of 14 confirmed patients they’ve studied. In this initial analysis, they could see one patient’s heart rate jump nine days before the person reported symptoms. In other cases, they only saw evidence of infection in the data when patients noticed symptoms themselves.

“The bottom line is it is working, but it’s not perfect,” said Stanford’s Michael Snyder.

Given the hype that often engulfs consumer gadgets, there’s plenty of reason for caution about tech charting an unknown path with a disease that’s still a mystery in many ways. Researchers still need to crunch more numbers to identify the difference between a patient with the coronavirus and another illness. And they need to do a lot more coronavirus testing on study participants to figure out whether they can detect an infection in people who don’t feel symptoms at all.

“I haven’t seen that subtlety embraced by most tech companies,” said Ben Smarr, a professor at the University of California, San Diego who is helping lead the data-crunching on the UCSF study, which hasn’t reported results. “I’m wary because I don’t want this to be used to sell people a false solution or false hope.”

Accuracy is the question that hangs over detecting the coronavirus from a gadget.

Fitness trackers started as a way to count steps, a relatively low-stakes measure. Marketers pushed the idea that everyone should take 10,000 steps per day, but it was never rooted in much science.

As tech companies have grown more interested in health care, they have added more sensors to wearables.