ICU admissions and in-hospital deaths linked to covid-19 in the Paris region are correlated with previously observed ambient temperature

ABSTRACT OBJECTIVE To study the effect of weather on severity indicators of coronavirus disease 2019 (covid-19). DESIGN Ecological study. SETTING Paris region. POPULATION Severely ill patients with covid-19. MAIN OUTCOME MEASURES Daily covid-19-related intensive care unit (ICU) admission and in-hospital deaths in the Paris region, and the daily weather characteristics of Paris midtown. RESULTS Daily ICU admissions and in-hospital deaths were strongly and negatively correlated to ambient temperatures, with a time lag. The highest Pearson correlation coefficients and statistically significant P values were found 8 days before occurrence of ICU admissions and 15 days before deaths. CONCLUSIONS The study findings show a strong effect of previously observed ambient temperature that has an effect on severity indicators of covid-19. Strengths and limitations of this study We assessed the link between weather characteristics with a time lag and covid-19-related hospital severity indicators. This is the first study, with reliable data, to find a strong negative correlation between previously observed ambient temperature with covid-19-related iCU admissions and in-hospital deaths. It is compatible with the natural history (including hospitalisation) of covid-19 outbreak in a highly developed country. We also report the duration after which iCU admissions and in-Hospital deaths occurs following temperature variation (respectively median of 8 and 15 days). Our analyses are mainly valid for temperate climate countries.