Early data from Fitbit study indicates it can predict COVID-19 before symptoms show

With the research gathered in its study, Fitbit hopes to create an algorithm that can detect diseases such as COVID-19 before symptoms start using physiological signs.
By Mallory Hackett
10:56 am

Fitbit may be able to detect COVID-19 in patients before they start to feel symptoms, based on early findings from the company’s “Assessment of physiological signs associated with COVID-19 measured using wearable devices” preprint study.

The study includes preliminary data that has yet to be peer reviewed by a medical journal.

With the research gathered in its study, Fitbit hopes to create an algorithm that can detect diseases such as COVID-19 before symptoms start by using physiological signs such as breathing rate, resting heart rate and heart rate variability.


Findings suggest that Fitbit wearables can detect nearly 50% of COVID-19 cases one day before participants report the onset of symptoms, with 70% specificity.

“This is important because people can transmit the virus before they realize they have symptoms or when they have no symptoms at all,” Conor Heneghan, director of research and algorithms at Fitbit, wrote in a blog post. “If we can let people know they should get tested a day before symptoms begin, they can isolate and seek care sooner, helping to reduce the spread of COVID-19.”

The study also indicates that breathing rate, resting heart rate and heart rate variability can be used to detect the onset of illnesses, especially when tracked when the user is asleep.

Researchers found that in many cases heart rate variability decreases, while resting heart rate and breathing rate increase, in people who have symptoms. In some cases, those measurements could signal changes in a person’s health nearly a week before symptoms were reported.

In addition to detecting early signals of COVID-19, the researchers also examined common symptoms, as well as severity, duration of illness and the symptoms most likely linked to hospitalization.

The most common symptom among participants with COVID-19 was fatigue, with 72% of participants reporting this. Other common symptoms were headache (65%), body ache (63%), decrease in taste and smell (60%), and cough (59%). Only 55% of participants with COVID-19 reported having a fever, which indicates that temperature screening alone may not be enough to understand who might be infected, according to researchers.

Shortness of breath and vomiting were the symptoms most likely to lead to hospitalizations, according to the data. Sore throat and stomach problems were the symptoms least likely to predict the need for hospitalization.

The duration of COVID-19 varies depending on the severity of the case. For example, those who had a mild case and who recovered on their own at home had an average duration of eight days. Those with moderate cases, who could recover at home but needed care from others, were sick for about 15 days. For severe cases, like those necessitating hospitalization, the average duration of illness was 24 days, but the study saw several cases lasting over two months.


The study invited Fitbit users in the U.S. and Canada to participate in a survey of those who had COVID-19 (if they had been tested) to report the symptoms they experienced and to provide demographic data such as age, sex, body mass index and relevant medical background information.

Participants began enrolling in May, and the data presented in the preprint study represents results collected up to July 14. More than 100,000 Fitbit users have enrolled so far, and have reported 1,000 cases of COVID-19.

Researchers are still seeking participants. Interested users can sign up for the study in the Fitbit app or online.


Fitbit has made other moves to use the health-monitoring capabilities of its wearable to aid in the fight against COVID-19.

In June, it announced the Ready for Work solution, a service comprising a daily health check-in for employees and an analytics dashboard for their employers, both of which are offered through Fitbit Health Solutions.

It also released a feature for the Fitbit app where users can connect with a doctor virtually and access information on exercising indoors.

Fitbit has also been actively developing an on-board ECG feature for its devices. Back in May, when the company launched the Fitbit Heart Study, it confirmed that it has wrapped up a pivotal trial and submitted the feature for approval from regulators. Photos of potential new devices circulating in the media also suggest the possibility of new ECG features on upcoming products.


“It’s clear that our bodies start to signal impacts from the disease before more noticeable symptoms appear,” Heneghan said in the blog post. “With these initial signals identified, we’ll continue our work in developing an algorithm to detect diseases like COVID-19 and focus on expanded research in a real-world environment.”



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