ABSTRACT
The Angiotensin-converting enzyme 2 (ACE2) protein is the receptor for different coronaviruses, including Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of Coronavirus disease 2019 (COVID-19). Previous studies suggested the hypothesis that nicotine could downregulate the expression of the ACE2. Due to the high level of nicotine intake, the objective of this preliminary study was to assess, at the ecological level, the correlation between tobacco smoking and the attack rate and severity of COVID-19 in the European Union (EU). We have found that there is a statistically significant negative correlation between the age-standardized prevalence of tobacco smoking and the attack rate of COVID-19 in member states of the EU [Spearmans correlation coefficient = -0.476 (95% confidence interval -0.117, -0.725) (p-value = 0.012)], meaning that in member states with a higher age-standardized prevalence of tobacco smoking the attack rate of COVID-19 has been so far lower. Further research is needed to understand the possible effect of nicotine exposure in the expression of the ACE2 protein.