JMIR Public Health Surveill. 2021 Feb 26. doi: 10.2196/27091. Online ahead of print.
ABSTRACT
BACKGROUND: Several studies reported a low prevalence of current smoking among hospitalized COVID-19 cases however, no definitive conclusions can be drawn.
OBJECTIVE: We investigated the association of tobacco smoke exposure with the nasopharyngeal swab (NPS) test result for SARS-CoV-2 infection and the disease severity accounting for possible confounders.
METHODS: The nationwide self-administered cross-sectional EPICOVID19 web-based survey was performed in an Italian population of 198,822 voluntary adults who filled in an online questionnaire between April 13 and June 2, 2020. For the present study, we analyzed 6857 individuals with known NPS test result. The associations of smoking status and the dose-response relationship with the positivity to NPS test and infection severity were calculated as odds ratios with 95% Confidence Intervals (OR, 95%CI) by means of analyzed using logistic and multinomial regression models adjusting for socio-demographic, clinical, and behavioral characteristics.
RESULTS: Out of the 6857 individuals (mean age 47.9 years, 65.9% females), 63.2% had never smoked, 21.3% were former and 15.5% were current smokers. Compared to non-smokers, current smokers were younger, more educated, less affected by chronic diseases, reported less frequently COVID-like symptoms, were less hospitalized and tested for COVID-19. In multivariate analysis current smokers had almost halved odds of a positive NPS test (OR 0.54, 95% CI 0.45-0.65) compared to non-smokers. We also found a dose-dependent relationship with tobacco smoke: mild smokers (OR 0.76, 95% CI 0.55-1.05), moderate (OR 0.56, 95% CI 0.42-0.73) and heavy smokers (OR 0.38, 95% CI 0.27-0.53). This inverse association persisted also when considering the severity of the infection. Current smokers had a statistically significant lower probability of having asymptomatic (OR 0.50 95%CI 0.27-0.92), mild (OR 0.65 95%CI 0.53-0.81), and severe infection (OR 0.27 95%CI 0.17-0.42) compared to never smokers.
CONCLUSIONS: Current smoking was negatively associated with SARS-CoV-2 infection with a dose-dependent relation. Ad-hoc experimental studies are needed to elucidate the mechanisms underlying this association.
CLINICALTRIAL: ClinicalTrials.gov NCT04471701.
PMID:33668011 | DOI:10.2196/27091
