Researchers focused on changes in the study participants’ heart rate variability (HRV). A high heart rate variability is a sign of an active, adaptable nervous system - and also signals that a person’s immune system is working well.
“The watch showed significant changes in HRV metrics up to seven days before individuals had a positive nasal swab confirming COVID-19 infection,” Dr. Robert P. Hirten, Assistant Professor of Medicine (Gastroenterology) at the Icahn School of Medicine and the study’s corresponding author, said.
‘Breakthrough’ in fight against COVID
For the “Warrior Watch Study,” researchers observed 297 health care workers at the Mount Sinai Health System between April 29 and September 29. They all wore Apple Watches and used the corresponding app on their phones. In individuals who later tested positive for COVID-19, the time between two heartbeats varied significantly less than in those who tested negative.
Information like this could be crucial in the fight against the coronavirus.
“Developing a way to identify people who might be sick even before they know they are infected would really be a breakthrough in the management of COVID-19,” Dr. Hirten said. After all, it is asymptomatic virus-spreaders who make it “difficult to contain this infection by using the traditional method of identifying someone who is sick and quarantining them.”
Fitness trackers turned COVID trackers
Mount Sinai’s “Warrior Watch Study” is ongoing. Other researchers have also found benefits in so-called wearables like the Apple Watch, Fitbit and other fitness trackers.
A study published in the journal Nature Biomedical Engineering found that smartwatch data can help detect COVID-19 before it’s diagnosed through a test. The researchers from Stanford University looked at factors including heart rate, number of daily steps or time asleep.
Retrospectively, they found for example that “63% of the COVID-19 cases could have been detected before symptom onset in real-time via a two-tiered warning system based on the occurrence of extreme elevations in resting heart rate relative to the individual baseline,” the authors state in their paper.
For the study, they had recruited 5,262 participants and then analyzed physiological and activity data of 32 of them who contracted COVID.