Smoking Is Associated With COVID-19 Progression: A Meta-analysis

Nicotine Tob Res. 2020 Aug 24;22(9):1653-1656. doi: 10.1093/ntr/ntaa082.


Introduction: Smoking depresses pulmonary immune function and is a risk factor contracting other infectious diseases and more serious outcomes among people who become infected. This paper presents a meta-analysis of the association between smoking and progression of the infectious disease COVID-19.

Methods: PubMed was searched on April 28, 2020, with search terms "smoking", "smoker*", "characteristics", "risk factors", "outcomes", and "COVID-19", "COVID", "coronavirus", "sar cov-2", "sar cov 2". Studies reporting smoking behavior of COVID-19 patients and progression of disease were selected for the final analysis. The study outcome was progression of COVID-19 among people who already had the disease. A random effects meta-analysis was applied.

Results: We identified 19 peer-reviewed papers with a total of 11,590 COVID-19 patients, 2,133 (18.4%) with severe disease and 731 (6.3%) with a history of smoking. A total of 218 patients with a history of smoking (29.8%) experienced disease progression, compared with 17.6% of non-smoking patients. The meta-analysis showed a significant association between smoking and progression of COVID-19 (OR 1.91, 95% confidence interval [CI] 1.42-2.59, p = 0.001). Limitations in the 19 papers suggest that the actual risk of smoking may be higher.

Conclusions: Smoking is a risk factor for progression of COVID-19, with smokers having higher odds of COVID-19 progression than never smokers.

Implications: Physicians and public health professionals should collect data on smoking as part of clinical management and add smoking cessation to the list of practices to blunt the COVID-19 pandemic.

Publication types

  • Meta-Analysis
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.
  • Systematic Review

MeSH terms

  • Betacoronavirus
  • COVID-19
  • Coronavirus Infections* / complications
  • Coronavirus Infections* / epidemiology
  • Coronavirus Infections* / physiopathology
  • Disease Progression
  • Humans
  • Pandemics*
  • Pneumonia, Viral* / complications
  • Pneumonia, Viral* / epidemiology
  • Pneumonia, Viral* / physiopathology
  • Risk Factors
  • SARS-CoV-2
  • Smoking* / epidemiology
  • Smoking* / physiopathology