Covid-19 has had a major impact on the transport systems around the world. Several transport-related policies were implemented in short period of time to contain the spread of the pandemic. These policies had a major influence on travel behaviour and people's perception towards the safety of different modes of transport, especially public transport, thus affecting several sustainable mobility initiatives. To build a resilient and sustainable transport system and to rebuild trust in public transport, it is important to understand the role of mobility in the spread of Covid-19 pandemic. The present study investigates the relationship between mobility and reported Covid-19 infections using data from Dublin city. Different modes of transport including traffic volume, bus passengers, pedestrians and cyclists were considered in the study during a forty week period. Multiple scenarios involving two-week lag and three-week lag of mobility data and Covid-19 infections were considered in building statistical models. Results showed that, 36.2 % of the reported Covid-19 infections after a two-week lag and 33% of the infections after a three-week lag can be explained using the level of mobility alone. The study further discusses the policy implications and strategies for ensuring a resilient and sustainable transport system.