Nicotine and smoking in the COVID-19 era.

The knowledge regarding the demographic characteristics of patients with Covid-19 and risk factors distribution is still evolving. Considering the role of cigarette smoking in the pathogenesis of lung diseases and the effect of nicotine on expression of the entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is important to determine the implications of smoking in COVID-19. In this brief report, by using the published articles in the literature, we aimed to compare the reported prevalence of smoking in patients with COVID-19 to the prevalence of smoking in the general population of the corresponding report. Binomial tests were conducted and a value of less than 0.05 was considered statistically significant. Among the screened papers, we found 12 peer-reviewed articles in which epidemiological characteristics of COVID-19 patients, including smoking status, were stated. Based on the descriptive reports of characteristics of COVID-19 patients, we observed a significantly lower proportion of COVID-19 patients with smoking history compared to what is expected, given the population average for each study's geographic area. This analysis of available data showed a lower prevalence of smoking in COVID-19 patients in comparison to the regional average. Considering the limitations of the study, the results should be interpreted with great caution and be viewed just as a preliminary report to motivate related basic and clinical researches.