Role of Environmental Temperature on the Attack rate and Case fatality rate of Coronavirus Disease 2019 (COVID-19) Pandemic

SARS-CoV-2 is a zoonotic Betacoronavirus causing the devastating COVID-19 pandemic. More than twelve million COVID-19 cases and 500 thousand fatalities have been reported in 216 countries. Although SARS-CoV-2 originated in China, comparatively fewer people have been affected in other Asian countries than in Europe and the USA. This study examined the hypothesis that lower temperature may increase the spread of SARS-CoV-2 by comparing attack rate and case fatality rate (until 21 March 2020) to mean temperature in January–February 2020. The attack rate was highest in Luxembourg followed by Italy and Switzerland. There was a significant (p = 0.02) correlation between decreased attack rate and increased environmental temperature. The case fatality rate was highest in Italy followed by Iran and Spain. There was no significant correlation between the case fatality rate and temperature. This study indicates that lower temperature may increase SARS-CoV-2 transmission (measured as an increased attack rate), but there is no evidence that temperature affects the severity of the disease (measured as case fatality rate). However, there are clearly other factors that affect the transmission of SARS-CoV-2, and many of these may be sensitive to interventions, e.g. through increased public awareness and public health response.