What human mobility data tell us about COVID-19 spread

Peoples' movements - both local and long-distance - have driven the spread of COVID-19, within and between communities. At the same time, although most contagion events involve human travel, not all human travel leads to contagion events, and deriving information about virus spread from what is known about human mobility remains a challenge. In the past two years, new datasets and analyses have shed fresh light on the problem.