The DETECT study is an app-based research program that analyzes participants’ wearable health data—including heart rates, sleep and activity levels—to more quickly detect the emergence of influenza, COVID-19 and other fast-spreading viral illnesses. Members of the public who are 18 or older and have a smartwatch or activity tracker, such as a Fitbit or Apple Watch, can join the study and consent to share their data by downloading the MyDataHelps mobile app.