A significant new study from Mount Sinai researchers has discovered that the Apple Watch and similar smartwatches can effectively predict a positive COVID-19 diagnosis up to a week before current PCR-based nasal swab tests.

Published in the peer-reviewed “Journal of Medical Internet Research,” the study effectively predicted coronavirus infections up to a week before tests provided confirmed diagnoses.

Several hundred healthcare workers participated in the research study, titled “Warrior Watch Study.” The research has collected data between April and September with a little help from a dedicated Apple Watch and iPhone app. As TechCrunch notes, the heart rate variability (HRV) patterns in participants have returned to normal roughly 1-2 weeks following a positive test.

A still from Apple's ad showing the back crystal on the Apple Watch along with the optical heart rate sensor

By combining HRV readings and common COVID-19 symptoms—including fever, aches, dry cough, gastrointestinal issues, and loss of taste and smell, among others—researchers have been able to predict a positive COVID+-19 diagnosis up to a week before a nasal test.

Detecting COVID without a swab test

As to what the study could lead to in terms of actual interventions, TechCrunch explains:

The study’s authors note that it can help anticipate outcomes and isolate individuals from others who are at risk. Most importantly, it provides a means for doing so remotely, allowing caregivers to anticipate or detect a COVID-19 case without even doing a physical exam or administering a nasal swab test, which can help take precautionary measures in high-risk situations when cases are suspected, possibly preventing any spread before someone is highly contagious.

The ongoing study will also test if the Apple Watch sensors might record sleep/activity patterns that in turn could be used to further increase the accuracy of COVID predictions.

Spotting COVID before symptoms appear

Prior medical studies conducted by Mount Sinai Health System in New York and Stanford University in California has hinted that wearable technology might indeed be capable of detecting coronavirus infections days before the first COVID-19 symptoms appear.

Published in Nature Biomedical Engineering, the studies have found the Apple Watch, Garmin, Fitbit and similar wearables can detect specific subtle changes in an individual’s heartbeat used to predict COVID-19 infections days before the first symptoms appear.

It’s unclear whether the Mount Sinai researchers are planning to open up their latest study to the general public through Apple’s Research app. Apple in the past partnered with medical institutions and researchers on heart-based studies that used the Apple Watch.

Based on findings in those studies, Apple was able to create new health features for the Apple Watch. One of those is the irregular heart rhythm notification that can point to a heart health change which could be indicative of a more serious condition, such as atrial fibrillation (AFib).