Back at the September 2020 event, as part of the announcement of the Apple Watch Series 6, Apple said it is collaborating with the Seattle Flu Study organization and the University of Washington to determine whether the Apple Watch can predict respiratory illnesses, including COVID-19.

The Apple Respiratory Study is now recruiting participants. If you would like to volunteer, you must live in the greater Seattle and be 22 years of age or older.
See also: Smartwatches may detect symptoms of COVID-19
Participants must wear an Apple Watch provided by the Seattle Flu Study organization at all times and complete short surveys in the Apple Research app.
See also: Apple Watch: How to stop low heart rate notifications
The study will use the data collected from the blood oxygen sensor of the Apple Watch Series 6 and heart rate monitoring to test and find patterns that could serve as early signs of respiratory infections, including COVID-19.
Previous Apple health studies have contributed to scientific research and have led to features that users exhibit, such as irregular heart function.
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In addition to the Seattle research, Apple announced two other health studies of the Apple Watch that are related to blood oxygen. This includes studies on asthma and heart failure.
Information source: 9to5mac.com
