This article focuses on the decline in the use of public transport in the context of the coronavirus disease 2019 (COVID-19) crisis in the Lyon metropolitan area, France. Using data from a web-based survey, supplemented by traffic counts and a qualitative survey, we explain this decline by the decrease in out-of-home activities such as work and the concomitant increase in teleworking, as well as by modal transfers. We test these explanations by multiple regression models that include socio-demographic, residential, professional and attitudinal variables. We conclude with a discussion on the lasting of these changes and their implications for mobility policy.