When a group of California researchers started a COVID-19 study in 2020 using fitness tracking rings, they didn’t know they would make a leap forward for an entirely different condition. In the earliest days of the pandemic, more than 20,000 people from 106 different countries signed up to participate in the TemPredict Study from the University of California, San Francisco, according to a Feb. 5 paper published in the journal Scientific Reports. The researchers set out to learn if off-the-shelf fitness and health trackers worn on the body could be used to detect the early symptoms of COVID-19,…