Abstract
Background: COVID-19 is an ongoing global pandemic with paucity of the understanding of the natural history of the disease and how it affects smokers. We aim to study the outcomes of COVID-19 in smokers in this descriptive review. Coronavirus disease 2019 caused by severe acute respiratory syndrome Coronavirus 2, gains entry to bronchial epithelial cells by attachment of the viral spike protein to Angiotensin-Converting Enzyme-2 (ACE-2) receptors. Accordingly, this review aims to understand the associated risk and worsen disease in relation to smoking and explore conflicting information regarding nicotine as well as its potential protective role. Methods: We conducted a non-systematic review of databases with search engines such as, PubMed, Google Scholar with keywords like “COVID-19,” “SARS-CoV-2,” “novel coronavirus,” smoking,” “smokers,” “nicotine.” It included English articles related to the epidemiology of COVID-19 in adult smokers, containing systematic reviews, meta-analysis, prospective and retrospective cohort studies, cross-sectional studies, case series, and case reports based on the relevance of titles and abstracts to the topic. Results: A total of 33 articles were reviewed. Smokers were 1.4 times more likely to have severe COVID-19 (RR = 1.4, 95% CI: 0.98 - 2.00), and 2.4 times more likely to require an ICU admission (RR = 2.4, CI: 1.43 - 4.04) when compared to non-smokers (n = 926). Current smokers were less likely to experience an adverse outcome (OR: 0.42, 95% CI: 0.24 - 0.74), compared to former smokers. 22% of current smokers and 46% of former smokers had more severe complications compared to non-smokers with COVID-19 infection. Current smokers had a case fatality rate of 38.5% (n = 1790). They had higher odds of mortality compared to non-smokers (OR = 1.25), especially males > 65 years age (OR = 2.51). Tobacco smoke upregulates inflammatory cytokines like TNF-α, IL-1β, and neutrophils by activating NF-k. Hence, it leads to increased epithelial cell permeability, mucus production, and impaired mucociliary clearance. The pro-inflammatory action of tobacco smoke impairs the basal laminar cells and causes endothelial dysfunction of the BBB and blood vessels, which leads to neurological, cerebrovascular, and thrombotic complications. Conclusion: Smoking is associated with worse outcomes and mortality in COVID-19. Public education about smoking cessation should be implemented along with standard guidelines to prevent disease progression in this susceptible population.
Highlights
With the emergence of the COVID-19 global pandemic, the scientific community has undertaken efforts to understand the epidemiology of the disease in order to mitigate adverse outcomes and the worldwide crisis
We conducted a nonsystematic review of databases with search engines such as, PubMed, Google Scholar with keywords like “COVID-19,” “SARS-CoV-2,” “novel coronavirus,” smoking,” “smokers,” “nicotine.” It included English articles related to the epidemiology of COVID-19 in adult smokers, containing systematic reviews, meta-analysis, prospective and retrospective cohort studies, cross-sectional studies, case series, and case reports based on the relevance of titles and abstracts to the topic
Current smokers were less likely to experience an adverse outcome (OR: 0.42, 95% CI: 0.24 - 0.74), compared to former smokers. 22% of current smokers and 46% of former smokers had more severe complications compared to non-smokers with COVID-19 infection
Summary
With the emergence of the COVID-19 global pandemic, the scientific community has undertaken efforts to understand the epidemiology of the disease in order to mitigate adverse outcomes and the worldwide crisis. Current smokers had a higher case fatality rate of 38.5% and were 1.45 times more likely to have morbid outcomes compared to their non-smoking counterparts [4]. As a modifiable risk factor, Smoking (modifiable risk factor) upregulates ACE2 receptor expression decreases serine protease inhibitors increasing susceptibility to COVID-19 infection smoking is a very crucial consideration in COVID-19, so this literature review aims to understand the risk of COVID-19 with smoking, the relation of smoking to the progression of the disease and clinical course, and explore debating information regarding nicotine as well as its potential protective role due to competition of nicotinic acetylcholine receptor with SARS-CoV-2 binding sites. This review aims to understand the associated risk and worsen disease in relation to smoking and explore conflicting information regarding nicotine as well as its potential protective role. Current smokers had a case fatality rate of 38.5% (n = 1790) They had higher odds of mortality compared to non-smokers (OR = 1.25), especially males > 65 years age (OR = 2.51). It leads to increased epithelial cell permeability, mucus production, and im-
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