How the Health Tracking on the Apple Watch Helped Me Realise I Had COVID-19

A month ago, I got a positive ART test the moment I tested myself after getting home from a 16-hour long flight. Most people would say they were surprised when they first saw their test, but for me, I was already somewhat expecting it. Why? Because the data from my Apple Watch had already alerted me to it.

Now, to be fair, I'm quite an odd person when it comes to tracking my health metrics. I go through the data very regularly, even though I'm not particularly focused on my fitness or exercise. In fact, my one big complaint previously about the Apple Watch was that there was no detailed sleep tracking, which is finally being rectified in the upcoming watchOS 9. Anyway, suffice to say I keep a very close eye on the data in my Health app.

It all started on 11th June (or 10th June in America), which was also around the time I suspect I caught the virus. Because I was travelling in America with a huge time difference, I had noted a slight uptick in my sleeping heart rate. It was typically around the high-40s to the low 50s. In America, it had gone up to rest between 60-80 BPM, so I was aware, but not overly concerned. What was of concern to me was my resting heart rate that had spiked from between 60-70 BPM all the way up to 94 BPM on this day.


That being said, I rationalised it by telling myself that it was probably just the jet lag and such stressing my body out. At this point, I hadn't had any symptoms or felt off. So I kept monitoring. On the 12th, the watch didn't track my sleep heart rate for some reason, but I did note my resting rate had gone down to a more reasonable 85 BPM.

On the 13th though, I was quite alarmed by the fact that my sleeping heart rate had spiked to a high of 99 BPM and a bad feeling was starting to creep up on me. Something that had never happened in my years of wearing an Apple Watch happened too: I received two high heart rate alerts. For those unaware, this alert is when your heart rate exceeds a preset BPM threshold (120 BPM in my case) for over 10 minutes while you're not exercising. This was also around the time I was leaving the hotel to get to the airport and catch my flight back home to Singapore, so I was quite glad I was going to be home if anything was going to happen. While waiting to check in at the airport and all throughout the wait to board the plane, I felt perfectly fine.


After take-off though, I had started to feel my throat dry up. Perfectly normal, I thought to myself, plane air is always on the dry side. Just to be safe, though, I kept my mask on whenever I wasn't eating or drinking and I refrained from moving around too much too.

The flight probably really stressed my body and immune system out, because my sleeping heart rate during that time was now at a new all-time high, between 91 and 99 BPM. My heart rate also spiked to a high of 154 BPM while I was getting off the flight and hauling my luggage around. I checked my heart rate variability (the higher the number, the better), which typically was around 40-50ms, and it had gone to as low as 18ms on that day. At that point, I had already made up my mind to test myself the moment I reached home.


And what a good idea it was. I reached home at 5am, immediately went into my room and did my ART test, which showed a very faint positive line. Thanks to keeping tabs on all this data, I had managed to catch it right at the onset and took all efforts to be as careful as possible during my 7 days isolation from my family, with nobody catching it from me. If the data hadn't been there and I only had that dry throat, I would certainly have not thought much of it and mingled with my family members for at least the first day, putting them at risk.

Today, Apple also released a new report on what the company has done in terms of their health initiatives, detailing their numerous studies on heart health, women's health, hearing and more. About a year ago, I saw a news piece on Apple collaborating with the University of Washington on a respiratory study to see if the Apple Watch could detect early signs of COVID-19 and I was intrigued by it. I did ask Apple if there was any result to that study, but there was no new update on that front.


So I thought to myself, what better time to share this story? After all, I myself am a result. A small, singular data point that might not change anything, sure, but one nonetheless. I'm certainly thankful that the data collected by the watch - heart rate, heart rate variability, blood oxygen percentage and more - allowed for me to figure out something was wrong with my body before my body started showing signs.

Credit: Apple

Now? My data is pretty much back to normal. Resting rate is back to below 70 BPM, my sleeping heart rate is still a little high at 50-80 BPM, but my heart rate variability is back up to a much more normal 55ms average, which is reassuring. Of course, what's normal for one person might not be for another, so regular tracking of your own data is still the best way to get a baseline for what's normal for you, rather than following an arbitrary guide online. Now to wait for the improved sleep tracking on watchOS 9.

Side