Climate affects global patterns of COVID-19 early outbreak dynamics

Gentile Francesco Ficetola; Diego Rubolini

is the (which was not peer-reviewed) The copyright holder for this preprint . https://doi.org/10.1101/2020.03.23.20040501 doi: medRxiv preprint reaching a minimum threshold of confirmed cases (25, 50 or 100), as the mean incubation period of Covid-19 is ca. 5 days (17) and, immediately after the first confirmed cases, many countries put in place unprecedented containment measures to mitigate pathogen spread and community transmission (18) . Variation at these early epidemic growth rates should best reflect the impact of local environmental conditions on disease spread. We restricted analyses to data reported 5 before March 19, as during that week many regions of the world adopted stringent containment measures even in absence of large numbers of reported cases. For instance, on March 17, 37 US states closed schools to prevent disease spread, including several states with less than 25 confirmed Covid-19 cases (19). We also considered additional factors that could affect SARS-CoV-2 transmission dynamics, such as human population density and government per-capita 10 health expenditure (see Methods).