The relationship between the use of electronic nicotine delivery systems (ENDS) and effects on pulmonary immune responses—a literature review

Introduction: The use of electronic nicotine delivery systems (ENDS), or vaping, is a relatively recent phenomenon, and there are various gaps in our current knowledge regarding the specific effects of e-cigarettes, such as their immunological effects. The importance of this question became even more relevant in light of the COVID-19 pandemic. Objective: This literature review examines the relationship between the use of electronic nicotine delivery systems (ENDS) and immunological effects to examine available information and identify gaps in the current knowledge. Our search strategy included studies focusing on the effects of ENDS on the immune response during infectious respiratory diseases such as COVID-19 and pneumonia. Methods: Peer-reviewed studies presenting quantitative data published from 2007, the year that e-cigarettes were introduced to the US market until 2022 have been included. All studies were indexed in PubMed. We excluded papers on THC and EVALI (E-cigarette, or Vaping Product, Use Associated Lung Injury) as we wanted to focus on the effects of nicotine devices. Results: Among the 21 articles that assessed the relationship between ENDS and immunological health effects, we found eight studies based on cell models, two articles based on both cell and mouse models, five articles based on mouse models, and six studies of human populations. Most of the articles identified in our review demonstrated a potential association between vaping and adverse immunological health effects. Discussion: Overall, the evidence from the cell and animal studies indicates that there is a positive, statistically significant association between vaping and adverse immune response during infectious respiratory diseases. The evidence from human studies is not conclusive.