While temperature measurements are widely used for screening COVID-19 patients at the entrances of many office buildings or malls, a new study suggests that a huge spike in resting heart rate is a more sensitive indicator of the disease.
Physiological data from commercial wearables showed increased resting heart rate around symptoms onset date that were more severe for COVID-19, but present in milder form for flu as well, said the study published in the journal Patterns.
"It's surprising to see that many screening tests at building entrances are all temperature-based since a lot of people don't develop a fever right away and there are so many things that cause fever other than COVID-19," said senior author Luca Foschini, Co-founder of US-based health and measurement company Evidation Health.
"A huge spike in resting heart rate is a more sensitive indicator of Covid. And for people with activity trackers, you could ask them permission to share that information for screening purposes, just like taking a temperature reading."
By analysing Fitbit data and self-reported symptoms, the researchers analysed trends in heart rate, step count, and symptom duration between patients with flu and those with COVID-19.
While both showed similar-looking spikes in resting heart rate and decreases in average step count, COVID-19 symptoms lasted longer and peaked later, said the study.
The findings confirmed that certain other symptoms are characteristic of Covid but not flu, like shortness of breath and coughing.
They also examined the impact of each illness on decreasing daily step count, finding that the impacts lasted much longer for COVID than for flu.
"We used step count to measure change in mobility, because you don't move as much when you're sick," said Foschini.
"Compared to their baseline, the number of steps didn't go back to normal for people with COVID, even after three or four weeks."
While data from wearables such as Fitbit can reveal a lot about these respiratory illnesses, the researchers said that it should be used as a general screening method, not a complete diagnostic tool.
