A controlled study of smokers, non-smokers, and e-cigarette users conducted by University of North Carolina School of Medicine found that e-cigarette users exhibited significantly altered immune responses to a model of influenza virus infection, suggesting increased susceptibility to disease.

The findings show that vaping changes the expression of genes and production of proteins in respiratory cells, as well as altering virus-specific antibody production, according to the study.

“In many of the study participants, we observed more changes to the immune response in e-cigarette users than we did in smokers,” said study author Meghan Rebuli, PhD, assistant professor in the UNC Department of Pediatrics and member of the UNC Center for Environmental Medicine, Asthma, and Lung Biology, in a press release. “All of these factors have the potential to adversely affect response to a virus and immunity post-infection. While we used influenza as a model, this suggests that e-cigarette users are likely more susceptible to respiratory viruses than are non-smokers, and this likely includes SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19).”

Additionally, researchers have been studying the potential effects of e-cigarettes, which are composed of thousands of chemicals, many of which are FDA-approved for ingestion but not inhalation. Although the inhalation of tobacco smoke has been linked to increased risk of viral infection, inhalation of e-cigarette aerosols has been linked to immune suppression within the respiratory tract, specifically the protective mucosal layer lining the inside of the nasal cavity, according to the study.

The study included non-smokers, cigarette smokers, and e-cigarette users between 18 and 40 years of age who were inoculated with live attenuated influenza virus (LAIV) vaccine to safely examine innate immune response. The researchers collected nasal epithelial lining fluid, nasal lavage fluid, nasal scrape biopsies, urine, and blood pre- and post-inoculation. Further, the team examined cytokines and chemokines, influenza-specific immunoglobulin A (IgA), immune gene expression, and markers of viral load.

Although the amount of markers of viral load did not differ among the 3 groups, the researchers found that expected increases in nasal epithelial lining fluid anti-LAIV IgA did not occur in e-cigarette users and cigarette smokers. Further, LAIV-induced gene expression changes in nasal biopsies differed in cigarette smokers and e-cigarette users compared with non-smokers, with a greater number of genes changed in e-cigarette users. This mostly resulted in decreased expression of immune genes critical for defense against viruses and generation of immune memory, according to the study.

“This is not good,” said study author Ilona Jaspers, PhD, in a press release. “We want to see IgA levels increase during infection. It’s the body’s natural way to defend against an invader. Here we saw that both smoking and e-cigarette use hampers IgA levels. The suppressed expression of important immune genes is also concerning and in line with an overall suppression of appropriate immune responses.”

In addition, altered immune response in e-cigarette users and cigarette smokers could make vaccines less effective in these groups.

“We don’t know for sure if people who vape are more susceptible to COVID-19, or if vaccines would be less effective for them,” Rebuli said in a press release. “But we know we never want to see suppression of genes, proteins, and antibodies involved in our immune response. And this is what we see in our data related to smoking and e-cigarette use.”

REFERENCE
Are E-cigarette users at greater risk of poor immune response to flu, COVID. UNC Health. https://news.unchealthcare.org/2020/11/are-e-cigarette-users-at-greater-risk-of-poor-immune-response-to-flu-covid/. Published November 12, 2020. Accessed November 18, 2020.