Tobacco smoking and COVID-19: an old enemy in a new guise. Review of current publications

The review summarizes the current data on the relationship of tobacco smoking, e-cigarette use and the novel coronavirus infection COVID-19. The socio-demographic characteristics of patients with COVID-19 and associated diseases, which indicate a possible relationship between smoking and the disease, are analyzed. Recent large meta-analyzes demonstrating the increased risk of progression, the development of severe complications and adverse outcomes of COVID-19 in smokers, as well as in patients with chronic obstructive pulmonary disease, for which smoking is a leading risk factor, are shown. It is believed that tobacco smoking and e-cigarette use causes dose-dependent activation of the angiotensin-converting enzyme-2 receptor, by which virus penetrates to host cell. This may explain the higher risk of complicated COVID-19 in smokers and vapers. There is conflicting data because some studies showed some relatively low smoking prevalence among patients with COVID-19 compared with general population. This, in particular, was associated with poor-quality data collection about smoking, but, nevertheless, was the basis for hypotheses about the protective effect of nicotine against COVID-19. This issue needs further large independent studies, but it is clear so far that smoking is associated with the progression and adverse outcomes of COVID-19