COVID-19 is a worldwide health emergency. Digital disease surveillance, including social media-based technologies, represents an innovative approach that may allow us to better understand and contain its transmission. Here, Bisanzio et al. use geolocation data from Twitter as a proxy for human mobility in order to track the early global spread of COVID-19 cases.
Throughout history, human travel has been heavily implicated in the spread of infectious disease. Increased connectivity via air travel can further facilitate the geographic spread of infectious diseases to vulnerable countries. Tuite and colleagues describe trends in international air passenger numbers and connectivity between countries with different capacities to detect and respond to infectious disease threats.