Wearable Fitness Trackers Could Help Detect COVID-19 Infections, Study Suggests

Wearable fitness trackers may be able to assist in detecting COVID-19 infections early by identifying changes in heart rate, sleep, and activity levels, according to a study published in Nature Medicine.

Researchers looked at data from a major study, called DETECT, which was launched in late March to collect information on potential symptoms and physiological changes like heart rate and sleep quality.

About one in five Americans own a wearable fitness tracker. Having just a small percentage of those involved in identifying COVID spread patterns could be a huge boost to public health, says the study's co-author, Giorgio Quer, PhD, of Scripps Research Translational Institute.

"Early identification of those who are pre-symptomatic or even asymptomatic would be especially valuable, as people may potentially be even more infectious during this period," he says. "That's the ultimate goal."

Technology That's Useful Beyond the Coronavirus

The recent study is not the first time it's been suggested that fitness trackers could play a role in detecting illness.

A study published in The Lancet in January noted that acute infections—such as the flu—can cause someone to have an elevated resting heart rate and changes in sleep routines.

Since being able to track flu prevalence and spread would be very useful for public health efforts, the authors of that study looked at data from nearly 50,000 Fitbit users, with identifying info stripped out. They found a correlation between flu activity and shifts in heart rates and sleep.

Flu predictions were significantly improved by looking at rising resting heart rates and decreased sleep quality, says the co-author of that study and lead author of the recent COVID study, Jennifer Radin, PhD, also of the Scripps Research Translational Institute.

How It Works

"Everyone has a unique resting heart rate," Radin says, "and that rate begins to climb upward when there's an infection, most likely as a response to inflammation in the body, especially when there's a fever."

That inflammation and fever can also sabotage sleep quality, so when the two are combined, there's a higher risk of infection, says Radin. This would be true for a range of possibilities, including the flu and COVID-19. If this data can be harnessed at a more local level—such as by county—then it would allow public health efforts to be more concentrated there.

For instance, a surge in sleep problems, resting heart rate elevation, and drop in physical activity could lead a state to send more resources to that area in anticipation of potential hospitalizations. It could also prompt greater awareness for people in that county to be more diligent about protecting themselves and avoiding in-person gatherings.

"Quick response is key for any public health effort because the focus needs to be on containing the issue and preventing more people from being infected," she says. That's just as true for the flu as it is for COVID. With contract tracers becoming overwhelmed in most parts of the country, looking at alternatives like using fitness trackers may become an option at some point.

Using Your Data

Apart from public health officials using the data, could an individual see these changed numbers on a tracker and get a head's up that infection might be happening? That's a trickier question, says Radin, but she notes that it's certainly possible.

One key step toward that capability is understanding your baseline, she adds. That means keeping track of your resting heart rate, usual physical activity, and sleep duration and quality. Keep in mind that these can all fluctuate to some degree, especially if you're pursuing habits like more physical activity.

For instance, the top way to get a lower resting heart rate is through regular exercise, because your cardiovascular system becomes more efficient, according to Robert Greenfield, MD, medical director of non-invasive cardiology and cardiac rehabilitation at MemorialCare Heart & Vascular Institute at Orange Coast Medical Center.

“As you become better conditioned, your resting heart rate will start to lower, because your heart won’t have to work as hard at rest, thanks to a more efficient system,” he says.