Smartwatches recognize Covid-19 long before the first symptoms

The heart rate variability (HRV) measured by smartwatch and the resting heart rate show in many cases days before the first symptoms that a person is sick with Covid-19.

In order to fight the Covid-19 pandemic, the early detection of new infections is crucial. In most countries, however, even rapid tests are not nearly enough to regularly check all residents for the new coronavirus SARS-CoV-2.

Scientists from the Mount Sinai Health System and Stanford University have now presented two independent studies, according to which smartwatches and fitness trackers can diagnose Covid-19 disease long before a person feels symptoms.

Heart rate variability

As part of the Mount Sinai Health System study published on the preprint server medRxiv, 300 subjects wore a conventional Apple Watch between April 29 and September 29, 2020. This measures the heart rate variability (HRV), i.e. the time between two heartbeats. In medicine, a high HRV is an indication of a healthy and powerful body.

We already knew that heart rate variability markers change as inflammation develops in the body, and COVID is an incredibly inflammatory event. It allows us to predict that people will be infected before they know it.

Covid-19 ensures a specific slowdown in HRV in the early stages. The data from the Apple Watch can therefore show that there is an infection with SARS-CoV-2 up to seven days before the first symptoms. The researchers also explain that the study was not funded by Apple and that other smartwatches and fitness trackers can in principle deliver the same results.

Increased resting heart rate

A study by Stanford University, which was published in the journal Nature Biomedical Engineering, evaluated the resting heart rate of 5,000 test subjects recorded with various smartwatches and fitness trackers. The data show that up to nine and a half days before the first Covid-19 symptoms, the resting heart rate increases.

This could be observed in 81 percent of the subjects who contracted Covid-19 during the study period. In two-thirds of the people, the health data showed an infection several days before the first symptoms.

Health data for early warning

In summary the studies show that smartwatches are not yet a precise diagnostic tool, but can alert people to a possible Covid-19 infection. The health data can thus be used for early warning so that people are more likely to go into quarantine and thus interrupt chains of infection.

In the future corresponding apps could automatically evaluate the data and, if there is any indication of an infection recommend a more precise test.