This study compiled data from 166 countries, and found that increases in both temperature and humidity were associated with reduced rates of new daily cases and deaths from COVID-19.
Wu, Y. et al. Effects of temperature and humidity on the daily new cases and new deaths of COVID-19 in 166 countries. Science of the Total Environment (2020). DOI: 10.1016/j.scitotenv.2020.139051
28 April 2020
This study compiled data from 166 countries, and found that an increase in outdoor temperature of 1°C and an increase in the relative humidity of 1% were found to decrease the daily cases of novel coronavirus by 3% and 0.85%, respectively. Both were also found to be associated with a reduced rate of daily death from COVID-19, but to a lesser degree. This effect, however, may not be seen in countries where there has been little community transmission. Although this evidence is preliminary, it may suggest that the SARS-CoV-2 virus is sensitive to outdoor temperature and humidity. This may be supported by the fact that previously-documented coronaviruses have also demonstrated seasonality. Additionally, other reasons such as the fact that lower temperatures can hinder the body’s ability to fight off infection, may also provide support for these findings.
Summary by: Max Solish