Abstract
BackgroundSmoking impairs lung immune function and damages upper airways, increasing risks of contracting and severity of infectious diseases. This paper quantifies the association between smoking and COVID-19 disease progression.MethodsWe searched PubMed and Embase for studies published from January 1–May 25, 2020. We included studies reporting smoking behavior of COVID-19 patients and progression of disease, including death. We used random effects meta-analysis, meta-regression and locally weighted regression and smoothing to examine relationships in the data.ResultsWe identified 46 peer-reviewed papers with a total of 22,939 COVID-19 patients, 5421 (23.6%) experienced disease progression and 2914 (12.7%) with a history of smoking (current and former smokers). Among those with a history of smoking, 33.5% experienced disease progression, compared with 21.9% of non-smokers. The meta-analysis confirmed an association between ever smoking and COVID-19 progression (OR 1.59, 95% CI 1.33–1.89, p = 0.001). Ever smoking was associated with increased risk of death from COVID-19 (OR 1.19, 95% CI 1.02–1.39, p = 0.003). We found no significant difference (p = 0.864) between the effects of ever smoking on COVID-19 disease progression between adjusted and unadjusted analyses, suggesting that smoking is an independent risk factor for COVID-19 disease progression. We also found the risk of having COVID-19 progression higher among younger adults (p = 0.001), with the effect most pronounced among younger adults under about 45 years old.ConclusionsSmoking is an independent risk for having progression of COVID-19, including mortality. The effects seem to be higher among young people. Smoking prevention and cessation should remain a priority for the public, physicians, and public health professionals during the COVID-19 pandemic.
Highlights
Smoking impairs lung immune function and damages upper airways, increasing risks of contracting and severity of infectious diseases
Study characteristics From the total of 4562 studies we found from our search, 237 studies were considered retrospective cohorts, prospective cohorts, or case series that provided clinical and demographic characteristics of COVID-19 patients
Seven studies [10, 12, 18, 27, 35, 37, 50] assessed whether the patient was a current, former, or never smoker, 15 [13, 15, 17, 21, 32, 40,41,42,43,44, 46, 47, 51, 52, 54] studies assessed whether the patient was a “current smoker”, 24 [8, 9, 11, 14, 16, 19, 20, 22,23,24,25,26, 28,29,30, 33, 34, 36, 38, 39, 45, 48, 49, 53] studies assessed whether the patient had a “history of smoking”
Summary
Smoking impairs lung immune function and damages upper airways, increasing risks of contracting and severity of infectious diseases. As of April 2021, the virus had infected over 150 million people and caused more than 3 million deaths [1]. Old people and those with preexisting medical conditions including respiratory disease, hypertension, diabetes, cardiovascular disease, and cancer are more vulnerable to becoming critically ill when infected [2]. Smoking may enhance the risk of COVID-19 by its biological effects and behaviors of smokers. The World Health Organization (WHO) has advised the public that smoking could increase the risk of contracting COVID-19 because the behavior of smokers involves contact of fingers with the lips and removal of the protective face masks to smoke [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
