https://www.sciencedaily.com/releases/2021/06/210609115549.htm

The study, led by Imperial College London researchers and published today in Proceedings of the National Academy of Sciences, is the first to incorporate environmental data into epidemiological models of the transmission of SARS-CoV-2, the virus behind COVID-19.

The team show that temperature and population density are the most important factors determining how easily the virus spreads, but only in the absence of mobility-restricting measures, such as lockdowns.