Last spring a new research study by Stanford University set out to determine if the sensors on the Apple Watch could be used to detect signs of COVID-19 even before symptoms have begun to appear, and as that research continues and is joined by another study, the results are starting to look promising.
In the case of the Stanford University study, the goal wasn’t focused exclusively on COVID-19, but rather whether ECG and respiratory rate data, as measured by the Apple Watch, could be used to track infectious diseases in general — an approach that obviously makes more sense as these studies often take years to be turned into an actual solution, and we’re all certainly hoping that COVID-19 won’t be with us for that long.
Stanford’s study was device-agnostic, so it wasn’t just confined to the Apple Watch, however Apple’s wearable is certainly one of the best devices for this thanks to its ECG monitoring capabilities and array of other advanced sensors.
Now, as reported by CBS News, it looks like Stanford’s efforts are being matched from another direction by New York’s Mount Sinai Health system, which has begun its own independent research study that looks at heart rate variability as a predictor of infectious diseases, including COVID-19.
The study, dubbed “Warrior Watch,” tracked nearly 300 health care workers at Mount Sinai who wore Apple Watches with a custom watchOS app between April 29th and September 29th. Participants were also required to provide their medical history, details on any prior COVID-19 tests or diagnoses, and compete daily surveys and SARS-CoV-2 naval PCR and serum antibody tests.
Each participant’s heart rate variability (HRV) was measured against a baseline of COVID-19 related systems, with researchers discovering that individuals who had actually been diagnosed with COVID-19 experienced lower HRV levels than COVID-negative individuals did.
Heart rate variability is the variation in the timing between each heartbeat, and can be used as an indicator of how well a person’s immune system is working.
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 are infected before they know it.Rob Hirten, assistant professor of medicine, Icahn School of Medicine
High HRV levels don’t necessarily reflect an elevated heart rate, but rather simply that a person’s nervous system is active, adaptable, and more resilient to stress. However, what remains unclear is the cause and effect relationship between lower HRV levels and COVID-19; in other words, are users with lower HRV levels more likely to contract COVID-19 because they already have a weakened immune system, or does the onset of COVID-19 cause the drop in HRV levels?
It’s also worth keeping in mind that the study was conducted with a relatively small sample group of 297 participants, only 13 of which reported a positive COVID-19 test, however the results showed measurable physiological changes solely in the COVID-positive group.
Elevated Heart Rates
These results also appear to be consistent with the separate research study conducted by Stanford, which found that 81 percent of COVID-positive participants experienced changes in their resting heart rates as early as nine days before the onset of any symptoms.
In the case of the Stanford research, which encompassed a wider variety of activity trackers, including the Apple Watch and devices form Garmin and Fitbit, the onset of symptoms was indicated by an extremely elevated heart rate.
The Stanford study also included a control group of more than 5,000 participants, however according to the results, which were published in Natural Biomedical Engineering in November, only 32 people in that group tested positive for the virus.
The Stanford team also created an alarm system that would alert wearers when their heart rate had been elevated for a sustained period of time to the level that would indicate possible infection, alerting users that they should self-isolate and avoid contact with others.
While there’s still a lot of research to be done before any definitive conclusions can be reached, the medical experts and scientists behind the two studies are hoping to leverage these kinds of devices that people are wearing all the time to assist with early warning and diagnosis, as well as identifying people who may be asymptomatic and capable of passing SARS-CoV-2 or another infectious virus along to others without even knowing it.