BY Fast Company 4 MINUTE READ

The Apple Watch already has a number of sensors that could effectively detect early signs of COVID-19, and the most important one–a pulse oximeter–may be on the way.

Toward the end of his life, one of Steve Jobs’s hopes for Apple was that it could play a role in helping people stay healthy. After he died, that ambition was most clearly expressed in the Apple Watch. The company has always pushed to make its wearable something more than a fitness tracker—a more powerful, clinically relevant device.

With the sinking realization that the coronavirus—or future pandemics like it—could be part of our lives for years to come, there could be no better time for Apple to push its development of the Watch harder in the direction it’s already heading.

COVID-19 causes a form of pneumonia that fills the tiny sacs in the lungs with pus and fluid until they harden and can no longer pull oxygen from the air. New Hampshire ER doctor Richard Levitan, after spending a week treating COVID-19 patients in New York City, noticed that COVID-19 patients often began experiencing “silent hypoxia” early on in the advance of the disease, meaning a slow and gradual reduction in the oxygen saturation of their blood.

But as Levitan wrote in an April 20 New York Times op-ed, these patients often don’t realize they’re having trouble breathing. They begin compensating by taking longer and deeper breaths as their oxygen levels gradually drop. Normal oxygen saturation level is around 95% to 97%, but by the time many people get to a hospital, their blood oxygen levels are down to as low as 50%. They must immediately be put on a ventilator, Levitan explained.

Blood oxygen levels are typically measured using a pulse oximeter, a small device that clips around the end of your index finger. They’re readily available to consumers.

“Widespread pulse oximetry screening for Covid pneumonia—whether people check themselves on home devices or go to clinics or doctors’ offices—could provide an early warning system for the kinds of breathing problems associated with Covid pneumonia,” Levitan wrote.

Blood oxygen can also be measured by sensors pressed against the wrist from the bottom of a wearable device. Both Garmin and Fitbit already sell fitness trackers with the feature built in. But the clinical accuracy of their readings is questionable. Fitbit displays the blood oxygen readings within the context of its sleep app, but not as a standalone feature. And Garmin says that its blood oxygen feature is purely for “recreational,” not “medical,” use. If Apple added such a feature the Watch, it would likely insist on a clinical-grade sensor and software, as it did with the device’s heart rate sensors.

Actually, an iFixit teardown of the first Apple Watch, released in 2015, showed that it already had the sensors needed to read blood oxygen levels. It’s possible that Apple has never  activated the feature because it couldn’t yet ensure clinical-grade accuracy.

But now there are signs Apple is getting ready to add pulse oximetry to the Watch. The Apple blog 9to5 Mac’s Zac Hall found evidence in snippets of code from Apple’s upcoming iOS 14 that the company is preparing the feature for the Apple Watch Series 6 and the WatchOS 7 operating system, both of which are expected later this year.

On March 20, the Food and Drug Administration effectively opened the door for feature additions like pulse oximetry when it announced a new policy that allows manufacturers of “non-invasive, vital sign measuring devices” to add features that might help doctors monitor COVID-19 patients remotely during the pandemic. Apple CEO Tim Cook said on Thursday’s earnings call that the FDA’s action is already enabling health providers to use the Watch’s electrocardiogram (ECG) function to monitor patients.

Apple, of course, isn’t saying whether it plans to use the new FDA policy as an opportunity to introduce pulse oximetry. But “you can be sure we’re looking at other areas,” Cook said of health-related features in general. “We see it as a huge opportunity for the company and a way for us to help a lot of people.”

Not everybody is as bullish as Levitan about widespread pulse oximetry screening. The American Lung Association reports that consumers have begun buying pulse oximeters in large numbers over the past several weeks as people have come to understand blood oxygen drops to be an early COVID-19 warning sign. The group is concerned that consumers will “fixate,” on blood oxygen readings, taking them out of context to wrongly self-diagnose COVID-19. It’s advising people not to buy the devices solely to detect COVID-19 without talking to their doctor.

“Low oxygen levels are usually not the sole indicator of having COVID-19,” said the Lung Association’s chief medical officer Albert Rizzo, M.D. in a statement. “Patients should concentrate on other symptoms such as cough, shortness of breath, chest discomfort, respiratory rate, and pulse rate.”

In his Times piece, Levitan also pointed out that people shouldn’t rush to the ER after a low blood oxygen reading without talking to their doctor first. He also wrote that falling blood oxygen saturation isn’t the only early physical manifestation of COVID-19. It’s often accompanies by subtle changes in heart rhythms. And that’s another reason the Apple Watch could be a powerful tool. In theory, an algorithm could be developed that would analyze both pulse oximetry and pulse readings from the Watch’s sensors to detect unique signs of Covid-19.

The Apple Watch is already being used in several studies about the potential of using wearable devices to detect signs of COVID-19. In one, Stanford Medicine, Fitbit, and Scripps Research are working together to develop algorithms that can recognize signs in the sensor data that the body is fighting off a viral illness. The study relies on skin temperature and heart rate change data collected from various kinds of wearable devices, including those made by Fitbit and Apple.

“Smartwatches and other wearables make many, many measurements per day–at least 250,000, which is what makes them such powerful monitoring devices,” said Stanford’s Michael Snyder, PhD, in a statement. “My lab wants to harness that data and see if we can identify who’s becoming ill as early as possible, potentially before they even know they’re sick.”

And that is a very good way of expressing Steve Jobs’s original vision for Apple’s role in health. We are allowing personal technology to reside closer to our bodies with things like smartwatches and smart earphones, and we’re moving toward a time when implantation of technology will be commonplace. This will happen for a lot of reasons, but it also may provide health providers with the early warning data they need to intervene before diseases advance and become clinically harder, and more expensive, to deal with. COVID-19, with its covert way of attacking the lungs, is a painful reminder of that need.

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