Wearables and COVID-19


At the time of writing, there are now more than 1.5 million diagnosed cases of coronavirus – or more correctly, SARS-CoV2, with potentially a far greater number of undiagnosed cases. In many countries (UK included), testing for the virus has been limited mainly to those who are already seriously ill.

There are huge numbers of people who are either asymptomatic or who have only mild symptoms. This page suggests that the proportion of asymptomatic cases among positive tests could be as high as 80%. Combining the lack of testing with the number of asymptomatic cases, it’s easy to see how many cases there may actually be.

Venn Diagram of UK cases: A = Population, B = Tested, C = Estimate of Infections

At a personal level, I travelled to Portugal relatively recently, returning on the 15th March. At the time, numbers of confirmed cases in Portugal were lower than the UK, and there were no travel restrictions in place. However, it’s interesting to note that in the two weeks following my trip, both myself and my partner had some mild cold-like symptoms.

Since we’re both young and athletic, the chances of being asymptomatic are likely to be quite high. However, until an effective antibody test becomes widely available, we may never know whether we did indeed contract the virus.


In the meantime, as wearers of fitness trackers, we both noticed some trends in our resting heart rate during the time period in question.

Here’s the resting heart rate data from my Garmin watch:

The Garmin RHR (resting heart rate) data is a little variable, so I had to apply some smoothing to reduce the day-to-day noise. You can see that after a bit of an alcohol-fuelled Christmas, my RHR settled down to between 44 and 46bpm for the most part.

The region highlighted in orange corresponds to the recent period with cold-like symptoms. The RHR was consistently elevated; in the 46-48bpm region.

And here’s my partner’s data, this time from a FitBit:

Now again, there’s a definite region of elevated heart rate (highlighted). Interestingly the start of this region aligns fairly well with the Garmin data – around the 13th March.

Closing Thoughts

It’s difficult to draw any definite conclusions from the RHR data, but it is interesting to see illness reflected in the data from both of our trackers at the same time. Given the incubation period (average ~5 days) for the virus, this suggests that my trip to Portugal was not the root cause – the heart rate rises too soon afterwards. However, that’s not to say that we couldn’t have been exposed to the virus a few days beforehand.

I would be interested to hear your own experiences over the past month – perhaps you also own a wearable that tracks resting heart rate? Have you noticed anything in the data? Drop me a message!

Of course, this is really waiting for a large organisation such as Garmin, Apple or Google/Fitbit to start analyzing their entire dataset.

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