The COVID-19 pandemic that emerged in December 2019 brought human life to a standstill. With over two-year since the pandemic originated from Wuhan, SARS-CoV-2 has caused more than 6 million deaths worldwide. With the emergence of mutant strains and COVID-19 surge waves, it becomes critically important to conduct epidemiological studies that allow us to understand the role of various environmental factors on SARS-CoV-2 infectivity. Our earlier study reported a strong negative correlation of temperature and COVID-19 incidence. This study is basically an extension to our previous study with global analysis of COVID-19 in northern hemisphere countries. This study aimed to see the correlation of temperature, sunlight and humidity with new cases of COVID-19 in northern hemisphere countries from March 2020 to February 2022. Month-wise univariate analysis indicated a strong negative correlation of temperature and sunlight with SARS-CoV-2 infectivity while inconsistencies were observed in correlation analysis in the case of humidity in winter months. Moreover, strong negative correlation between average temperature of winter months and COVID-19 cases exists as evidenced by Pearson, Spearman and Kendall analysis. In addition, correlation pattern between monthly temperature and COVID-19 cases of a country mimics to that of sunlight of a country. This pilot study proposes that low temperatures and low sunlight might be additional risk factors for SARS-CoV-2 infectivity mostly in northern hemisphere countries.
Effect of environmental factors on SARS-CoV-2 infectivity in northern hemisphere countries: A Two-Year Data analysis