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Smoking and COVID-19: hospitalized smokers are far fewer than expected but have more severe disease

Jun 29, 2020

Researchers emphasize once again the need to examine nicotine as a potential therapeutic option for COVID-19 

Link: https://journals.sagepub.com/doi/10.1177/2040622320935765

Release summary text

A new study published in the journal “Therapeutic Advances in Chronic Disease” provides important insight to the issue of smoking and COVID-19. The number of smokers with severe COVID-19 that requires hospitalization is by far lower than expected based on population smoking rates. The very few smokers who are eventually hospitalized have higher odds for severe disease and adverse outcome.

Full text

Researchers from the University of Patras, University of West Attica, University of Catania and University of New York performed a meta-analysis of 30 studies on the association between smoking and COVID-19. This is the largest meta-analysis published on this subject till now, with a total of 11.104 hospitalized patients of whom 961 were smokers. The authors calculated the proportion of hospitalized patients with COVID-19 who were smokers compared to the population smoking rates. The latter was strictly adjusted for gender and age, which clearly underestimated the population rates and the expected smoking prevalence.

The proportion of COVID-19 patients who were smokers was 3-4 times lower than the expected (population-based) smoking prevalence, even with the strictest gender and age-adjustment. The very few smokers who ended up being hospitalized had 53-59% higher odds of having an adverse outcome compared with non-smokers.

Prof. Konstantinos Farsalinos, author of the study, made the following statement:

This is the largest meta-analysis of smoking and COVID-19, with 30 studies examined. It is also the first study that presented both the prevalence of smoking among hospitalized COVID-19 patients and its association with severe disease and adverse outcome. While we found that smoking was associated with higher odds of adverse outcome, we noticed that the number of smokers that develop severe COVID-19 that requires hospitalization was only 1.3rd – 1/4th the expected number. This is crucial in understanding the effects of smoking, since the accurate conclusion is that very few smokers get hospitalized for COVID-19, but this small proportion of smokers may have more serious disease than non-smokers. These findings fully support our hypothesis, presented since April, that nicotine could have therapeutic benefits in COVID-19. This needs to be urgently examined.


The findings of the study support that the increased risk for severe disease and adverse outcome is confined to hospitalized smokers and not to the general population of smokers. This has been a largely consistent finding that has been omitted in previous studies. The authors make a clear statement that smokers should be advised to quit. However, the very low number of smokers who get hospitalized for COVID-19 highlights once again the issue of pharmaceutical nicotine having potential beneficial effects on COVID-19, a hypothesis that has been recently presented in peer-reviewed publication and that needs to be further investigated, according to the authors.

In fact, the study findings could be explained, at least in part, by the fact that nicotine intake is discontinued immediately after smokers enter the hospital, depriving them of the potential beneficial effects of nicotine.

Regarding the data, Prof. Riccardo Polosa, founder of the COEHAR, said:

“Whether tobacco smoking is truly protective for SARS-CoV-2 infection and/or COVID-19 outcomes is not yet certain. And the Jury is still out. But one thing is for sure. The counter-intuitive data on smoking prevalence in our meta-analysis do not incriminate smoking as a risk factor for susceptability to SARS-CoV-2 infection and to hospitalization for COVID-19. A corollary of this – given that combustion-free-nicotine-delivery-systems are much less toxic than cigarettes – is that vaping and using Heat-no-Burnt are highly unlikely to be a risk factor for COVID infection and/or disease”

GENERAL INFO:

Title . Current smoking, former smoking and adverse outcome among hospitalized COVID-19 patients: a systematic review and meta-analysis


Authors. Konstantinos Farsalinos, Anastasia Barbouni, Konstantinos Poulas, Riccardo Polosa, Pasquale Caponnetto, Raymond Niaura.

Therapeutic Advances in Chronic Disease. https://doi.org/10.1177/2040622320935765 

Supplemental material: https://journals.sagepub.com/doi/suppl/10.1177/2040622320935765

Press office: valeria.nicolosi@coehar.it