Despite the limited data available, research is showing a direct link between smoking and coronavirus progression and severity.
In patients infected by the novel coronavirus (COVID-19), smoking may lead to greater disease progression and may increase the risk of more adverse outcomes, according to a systematic literature review published in Tobacco Induced Diseases.
Is There a Link Between Smoking and Coronavirus Severity?
The COVID-19 virus is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). For many people with COVID-19, the most common symptoms include fever, cough, and shortness of breath. Some patients, particularly those with comorbidities, pre-existing medical conditions, or certain risk factors (eg, smoking), may be at an increased risk for more severe symptoms and worse prognosis.
Medical Literature Suggests Smoking May Exacerbate COVID-19
Researchers from the Harvard School of Dental Medicine and the University of Crete in Greece performed a systematic review of the available literature that reported the smoking status of patients with COVID-19. The aim of the study was to assess the association between smoking and coronavirus disease progression.
In this review, a total of 5 retrospective and prospective studies conducted in China — with 4 of these studies conducted in Wuhan — were included for analysis. All 5 studies included in the review covered December 2019 and January 2020, the first 2 months of the COVID-19 pandemic.
A study that included 191 participants found that 9% of patients with COID-19 who smoked had died from complications associated with the virus. This was compared to 4% of patients who died but didn’t smoke. There was no statistical significant difference between the 2 groups (p=0.21).
In another study of 140 patients with COVID-19, a higher proportion of patients with severe disease were current smokers and former smokers (3.4% and 6.9%, respectively). In contrast, 0% and 3.7% of patients with non-severe disease were current smokers and former smokers, respectively (odds ratio [OR], 2.23; 95% CI, 0.65–7.63; p=0.2).
A study of 78 patients with COVID-19 found that those with adverse outcomes were significantly more likely to have a history of smoking compared to the cohort of patients with improvement or stabilization in their disease (27.3% vs 3.0%, respectively; OR, 14.28; 95% CI, 1.58–25.00; p=0.018).
This study was a systematic review of the literature regarding the 2019 to 2020 COVID-19 pandemic. As such, the number of studies for this pandemic is currently sparse. The researchers did not perform a meta-analysis of the data in these 5 studies that reported associations between smoking and coronavirus.
Additionally, while some of the studies included in this review did report a higher proportion of current smokers with greater disease progression and risk of adverse outcomes, the differences between current smokers and non-smokers did not always reach statistical significance. More studies are needed to validate these findings.
Vardavas CI, Nikitara K. COVID-19 and smoking: A systematic review of the evidence. Tob Induc Dis. 2020;18:20.