by Douglas Quine, PhD

Many people today have wearable devices to monitor their exercise and heart rate such as FitBits and SmartWatches. Last spring, as I was traveling in Ireland, I developed a “chest cold” for two days and tested positive (lateral flow antigen test) for COVID-19. It was only a mild case, for which I gave credit to my COVID vaccinations.

My 10-day hotel quarantine provided time for personal reflection and research. I was interested to see on my FitBit that my normally low baseline heart rate was climbing daily on April 5 (first positive), April 6 (no test), April 7 (positive), and April 8 (positive) after which it declined from April 9 to April 13 as I tested positive daily and recovered. Having returned to baseline heart rate for a couple of days, I tested COVID negative on April 15th.

These observations did not provide any real-time diagnostic value to me of the COVID onset since the heart-rate elevation on the day of first positive was not sufficient to predict the infection. However, such device data might be helpful in identifying the onset of infection in people who were not self-testing during the early onset of symptoms but can look back at their historical heartrate records.

Since my observations, I’ve seen a number of mentions and articles about the detection of the body’s physiological response to COVID infections and COVID vaccines (peaking on day 2 and returning to normal after days 4 to 6) by wearable devices. Most of them are summarized HERE.