Abstract: Methods, systems, and devices for illness detection are described. A method may include receiving physiological data associated with users, the physiological data being continuously collected via wearable devices associated with the respective users. The method may include identifying baseline physiological data for each user based on a first subset of the physiological data for each respective user. The method may include inputting a second subset of the physiological data and the baseline physiological data for each user into a classifier, and identifying an illness risk metric associated with each user based on the second subset of the physiological data and the baseline physiological data for each respective user.