Weather as a potential cause of regional differences in the dynamics of the COVID-19 epidemic in Poland - implications for epidemic forecasting.

Introduction Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the SARS-CoV-2 coronavirus. Objectives We aimed to analyze the correlation between six different meteorological parameters and the dynamics of the COVID-19 epidemic in 16 administrative regions (voivodeships) of Poland. Patients and methods Current analysis was based on data acquired from epidemiological reports published by the Polish Ministry of Health. For each of the 16 voivodeships, one synoptic station was selected to provide data on six meteorology parameters: maximum daily temperature, minimum daily temperature, variability of daily temperature, sunshine duration, relative humidity and wind speed. Results For all voivodeships, new COVID-19 cases were correlated with relative humidity (0.41), maximum daily temperature (-0.41), variability of daily temperature (-0.40), and sunshine duration (0.35). For all parameters, a similar time lag was obtained between -14 and -10 days. Such correlation for the wind speed was not statistically significant for most of the voivodeships. New hospitalizations due to the COVID-19 were correlated with the daily maximum temperature (-0.48 with a time lag of -10 days) and sunshine duration (-0.45 with a time lag of -10 days). Conclusions The delayed effects (10-14 days lag) of the meteorological factors on the incidence of COVID-19 and the risk of hospitalization due to the COVID-19 were observed. Relative humidity and the maximum daily temperature had the highest impact on the dynamics of the COVID-19 epidemic in each of the 16 administrative regions in Poland.