https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7953961/
>Our findings suggest that current smoking appears to significantly lower the odds of Covid-19 occurrence by –36% compared to nonsmokers and former smokers. However, the odds ratio will over-estimate the strength of the relative risk reduction (particularly as the prevalence of the outcome was high). Univariable and multivariable analyses identified and retained, respectively, that significant independent association (Table 3), as well as age >50 years. We found no significant association between Covid-19 and BMI, sex, or blood group. The Covid-19 clinical picture also appeared to differ according to smoking status, with fewer general symptoms (fever, asthenia, and headache) and respiratory signs (cough and dyspnea) among current smokers and some evidence of less severe infections—for example, among 20 patients requiring oxygen therapy, only two were current smokers, Previous studies showed conflicting results with most studies finding higher levels of severe Covid-19 in smokers (usually older and chronic obstructive pulmonary disease [COPD] patients).15
>Our findings suggest that current smoking appears to significantly lower the odds of Covid-19 occurrence by –36% compared to nonsmokers and former smokers. However, the odds ratio will over-estimate the strength of the relative risk reduction (particularly as the prevalence of the outcome was high). Univariable and multivariable analyses identified and retained, respectively, that significant independent association (Table 3), as well as age >50 years. We found no significant association between Covid-19 and BMI, sex, or blood group. The Covid-19 clinical picture also appeared to differ according to smoking status, with fewer general symptoms (fever, asthenia, and headache) and respiratory signs (cough and dyspnea) among current smokers and some evidence of less severe infections—for example, among 20 patients requiring oxygen therapy, only two were current smokers, Previous studies showed conflicting results with most studies finding higher levels of severe Covid-19 in smokers (usually older and chronic obstructive pulmonary disease [COPD] patients).15
