Methods, systems, and apparatus, including computer programs encoded on computer-storage media, for geofencing and location tracking for predicting and limiting disease exposure. In some implementations, location tracking data is received indicating locations of user devices over time. Location tags specifying visits of the user devices to different locations indicated by the location tracking data are defined. A geofence is assigned to each of the location tags to specify a geofenced area corresponding to the location tag. Disease transmission scores are assigned to first location tags representing visits of a first user. A disease exposure score is determined for a second user whose user device is determined, based on the location tracking data, to have entered at least one of the geofenced areas corresponding to the first location tags.
