The association between tobacco smoking, second-hand smoke and novel products, and COVID-19 severity and mortality in Italy. Results from the COSMO-IT study

Background. Despite the robust evidence of an excess risk of COVID-19 severity and mortality in ever smokers, the debate on the role of current and ex-smokers on COVID-19 progression remains open. Limited or no data are available on the link between electronic-cigarette (e-cigarette), heated tobacco product (HTP) and second-hand-smoke (SHS) exposure and COVID-19 progression. To fill this knowledge gap, we undertook the COvid19 and SMOking in ITaly (COSMO-IT) study.Methods. A multi-centre longitudinal study was conducted in 2020-2021 in 24 Italian hospitals on a total of 1820 laboratory-confirmed COVID-19 patients. We estimated multivariable odds ratios (OR) and 95% confidence intervals (CI), to quantify the association between smoking-related behaviours (i.e., smoking status, e-cigarette and HTP use, and SHS exposure) and COVID-19 severity (composite outcome: intubation, intensive care unit admission and death), and mortality.Results. Compared to never smokers, current smokers had an increased risk of COVID-19 mortality (OR=2.17; 95% CI=1.06-4.41). E-cigarette use was non-significantly associated to an increased risk of COVID-19 severity (OR=1.60; 95% CI=0.96-2.67). An increased risk of mortality was observed for exposure to SHS among non-smokers (OR=1.67; 95% CI=1.04-2.68), the risk being particularly evident for exposures of >= 6 hours/day (OR=1.99; 95% CI=1.15-3.44).Conclusions. This multicentric study from Italy shows a dismal COVID-19 progression in current smokers and, for the first time, in SHS exposed non-smokers. These data represent an additional reason to strengthen and enforce effective tobacco control measures and to support smokers in quitting.

Automated summary

Despite the strong evidence of increased severity and mortality risk in smokers with COVID-19, the impact of current and ex-smokers on disease progression remains uncertain. This study examines the association between smoking-related behaviors and COVID-19 severity and mortality, including e-cigarette use and second-hand smoke exposure.