Respiratory InfectionsMeta-analysis: COVID-19 Disease Severity Correlates With Smoking StatusLansiaux, Édouard*; Pébaÿ, Philippe P. PhD†; Picard, Jean-Laurent MSc‡; Forget, Joachim MD, PhD§Author Information *Henry Warembourg School of Medicine, Lille University, Lille ‡National Conservatory of Arts and Crafts §French National Assembly, Paris, France †NexGen Analytics, Sheridan, WY Disclosure: The authors declare that they have no conflicts of interest. Address correspondence to: Édouard Lansiaux, Henry Warembourg School of Medicine, Lille University, Lille 59000, France. E-mail: email@example.com. Clinical Pulmonary Medicine: July 2020 - Volume 27 - Issue 4 - p 99-104 doi: 10.1097/CPM.0000000000000364 Buy Metrics Abstract The novel Coronavirus Disease 2019 (COVID-19) disease is a contagious acute respiratory infectious disease whose causative agent has been demonstrated to be a new virus of the coronavirus family, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Multiple studies have already reported that risk factors for severe disease include older age and the presence of at least one of several underlying health conditions. However, a recent physiopathologic report and the French COVID-19 scientific council have postulated a protective effect of tobacco smoking. Thanks to a meta-analysis, we have been able to demonstrate the statistical significance in this regard of 12 series from China, France, and the United States, reporting 3 different smoking statuses (current smoker, former smoker with a smoking history) and disease severity [with odds ratio of 1.78 (1.08-3.10), 4.60 (3.13-7.17), 2.74 (0.63-5.89), respectively]. Subsequently, and using a Bayesian approach, we have established that past and present smoking is associated with more severe COVID-19 outcomes. Finally, we refute claims linking general population smoking status [N=O(108) or O(109)] to much smaller disease course series [N=O(104)]. The latter point, in particular, is presented to stimulate academic discussion, and must be further investigated by well-designed studies. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.