“… 4 , 9 , 10 , 11 In addition, recent work has explored how wearables may be used for real-time detection or retrospective analysis of COVID-19, for example, as a way to reduce the spread of infection. 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 Many of these approaches use a physiological signal from wearables, such as heart rate (HR), along with black box or machine learning methods to classify case status or disease progression. 22 , 23 , 24 …”