When someone’s lungs are exposed to flu or other infections the adverse effects of smoking or vaping are much more serious than among people who do not smoke or vape.
By Stanton A. Glantz, PhD – Director, Center for Tobacco Research Control & Education – UCSF – March 6, 2020.
Smoking is associated with increased development of acute respiratory distress syndrome (ARDS) in people with a risk factor like severe infection, non-pulmonary sepsis (blood infection), or blunt trauma. People who have any cotinine (a metabolite of nicotine) in their bodies – even at the low levels associated with secondhand smoke – have substantially increased risk of acute respiratory failure from ARDS (paper 1, paper 2, paper 3).
The recent excellent summary of the evidence on the pulmonary effects of e-cigarettes reported multiple ways that e-cigarettes impair lungs’ ability to fight off infections:
Effects on immunity
Reporting of respiratory symptoms by e-cigarette users suggests increased susceptibility to and/or delayed recovery from respiratory infections. A study of 30 healthy non-smokers exposed to e-cigarette aerosol found decreased cough sensitivity.82 If human ciliary dysfunction is also negatively affected, as suggested by animal and cellular studies,83 the combination of reduced coughing and impaired mucociliary clearance may predispose users to increased rates of pneumonia. Exposure to e-cigarettes may also broadly suppress important capacities of the innate immune system. Nasal scrape biopsies from non-smokers, smokers, and vapers showed extensive immunosuppression at the gene level with e-cigarette use.84 Healthy non-smokers were exposed to e-cigarette aerosol, and bronchoalveolar lavage was obtained to study alveolar macrophages.46 The expression of more than 60 genes was altered in e-cigarette users’ alveolar macrophages two hours after just 20 puffs, including genes involved in inflammation. Neutrophil extracellular trap (NET) formation, or NETosis, is a mode of innate defense whereby neutrophils lyse DNA and release it into the extracellular environment to help to immobilize bacteria, a process that can also injure the lung.85 Neutrophils from chronic vapers have been found to have a greater propensity for NET formation than those from cigarette smokers or non-smokers.57 Given that e-cigarettes may also impair neutrophil phagocytosis,86 these data suggest that neutrophil function may be impaired in e-cigarette users. [emphasis added]
Studies in animals reinforce and help explain these human effects:
Two weeks of exposure to e-cigarette aerosol in mice decreased survival and increased pathogen load following inoculation with either Streptococcus pneumoniae or influenza A, two leading causes of pneumonia in humans.97 Furthermore, the aerosol exposure may lead to enhanced upper airway colonization with pathogens and to virulent changes in pathogen phenotype, as shown with Staphylococcus aureus.98 99 Thus, although more studies are needed, the animal data suggesting that vaping leads to an increased susceptibility to infection would seem to correlate with the population level data in young adult humans, whereby vapers have increased rates of symptoms of chronic bronchitis.23 [emphasis added]
A meta-analysis of the relationship between smoking and influenza found that smokers were more likely to be hospialized and admitted to the ICU.
Consistent with this science, analysis of deaths from corona virus in China shows that men are more likely to die than women, something that may be related to the fact that many more Chinese men smoke than women. However, one study from China that evaluated predictors of death among all people hospitalized with COVID-19 did not find an association with smoking. Another study from China of patients diagnosed with COVID-19 associated pneumonia who had been in the hospital for two weeks reported that the odds of disease progression (including to death) were 14 times higher among people with a history of smoking compared to those who did not smoke. This was the strongest risk factor among those examined. A review of the available literature done in mid-March 2020 found 5 relevant papers, all from China. Three of the five papers did not find statisticaly significant differences between smokers and nonsmokers in terms of disease progression, but the studies were generally small, which means they had low power to detect an effect if it was there. One did not report a p value and the other (noted earlier in thins paragraph) found worse outcomes for smokers. The general pattern in the non-significant studies was for worse outcomes among the smokers. The authors concluded, “with the limited available data, and although the above results
are unadjusted for other factors that may impact disease progression, smoking is most likely associated with the negative progression and adverse outcomes of COVID-19.”
Dr. Nora Volkow, director of the National Institute on Drug Abuse, posted an article on her blog “COVID-19: Potential Implications for Individuals with Substance Use Disorders,” that stared off by saying
As people across the U.S. and the rest of the world contend with coronavirus disease 2019 (COVID-19), the research community should be alert to the possibility that it could hit some populations with substance use disorders (SUDs) particularly hard. Because it attacks the lungs, the coronavirus that causes COVID-19 could be an especially serious threat to those who smoke tobacco or marijuana or who vape.
She goes on to address other drug use and how COVID-19 could interact with them, including noting that
Vaping, like smoking, may also harm lung health. Whether it can lead to COPD is still unknown, but emerging evidence suggests that exposure to aerosols from e-cigarettes harms the cells of the lung and diminishes the ability to respond to infection. In one NIH-supported study, for instance, influenza virus-infected mice exposed to these aerosols had enhanced tissue damage and inflammation.
The whole blog post is worth reading.
In addition, an article in Scientific American, “Smoking or Vaping May Increase the Risk of a Severe Coronavirus Infection,” summarizes how smoking and vaping affect the lungs and the immune system that is consistent with the view that using these products increases the risk of infection and worse outcomes. CNN also has a good story, “How smoking, vaping and drug use might increase risks from Covid-19.”
CDC, FDA, the Surgeon General, state health departments and everyone (including comedians, such as John Oliver who spent his whole show on the issue last weekend) working to educate the public on how to lower risk of serious complications from covid-19 should add stopping smoking, vaping, and avoiding secondhand exposure to their list of important preventive measures.
This would also be a good time for cities, states private employers and even individual families to strengthen their smokefree laws and policies – including e-cigarettes — to protect nonsmokers from the effects of secondhand smoke and aerosol on their lungs and to create an environment that will help smokers quit.
(updated March 20, 2020)
Stanton A. Glantz, PhD – Director, Center for Tobacco Research Control & Education – UCSF – March 6, 2020.
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