In a review of five studies, tobacco was associated with the negative progression and negative outcomes of COVID-19 (Vardavas and Nikitara, 2020) but Lippi's preliminary meta-analysis on these five studies concluded to a non significant association (Lippi and Henry, 2020), albeit with several statistical caveat (Lo and Lasnier, 2020)(Guo, 2020). Active smoking increased the risk of severe COVID-19 in an 11 studies meta-analysis (Zhao et al., 2020), but the result was heavily influenced by one study (Guan et al., 2020b), which was the largest one and also the only one to distinguish current and ex-smokers. Finally, a large meta-analysis (on 19 studies, 9 peer-reviewed papers with a total of 11,590 COVID-19 patients) showed a significant association between smoking (current and ex) and progression of COVID-19 (OR 1.91, 95% CI1.42–2.59, p = .001) (Patanavanich and Glantz, 2020). Berlin et al. underlined the symptoms similarities between the COVID-19 and the coronavirus outbreak in 2013, wherein tobacco smoking was involved in prevalence and fatality rates (Berlin et al., 2020). Smokers, especially former smokers, may be more susceptible to 2019-nCoV and have different infection
