Vaping And COVID-19: Plausibility And Causality

By David Jaroslaw, Christopher Gismondi and Naira Gorovits
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Law360 (October 22, 2020, 6:20 PM EDT) --
David Jaroslaw
David Jaroslaw
Christopher Gismondi
Christopher Gismondi
Naira Gorovits
Naira Gorovits
The first case of COVID-19 in the U.S. was reported in January. As of this writing, the U.S. has the world's highest number of COVID-19 cases of any country, with nearly 7.5 million of the more than 35 million cases reported worldwide.

Given that COVID-19 is primarily a respiratory disease, and that vaping involves drawing a heated vapor through the mouth and into the lungs, it was perhaps inevitable that some scientific researchers would ask whether vaping increases susceptibility to, or severity of, COVID-19. It was perhaps equally inevitable that even the possibility that such a relationship might exist would lead to liability claims against vaping product manufacturers.

However, the very newness of the disease, and our accordingly limited understanding of its mechanisms and epidemiology, raise the question of whether plaintiffs bringing cases alleging a nexus between vaping and COVID-19 will be able to prove causality, as required under tort law principles — or if, instead, they will able to prove only what is, in essence, plausibility.

In fact, less than three months elapsed between the first reported COVID-19 case in the U.S. and the first vaping-related COVID-19 liability claim. In April, an allegation that vaping put persons who contracted COVID-19 at greater risk of more serious complications was added to the claims asserted in the federal court multidistrict litigation pending in the U.S. District Court for the Northern District of California against Juul Labs Inc. and other vape manufacturers and distributors.

In most exposure-related product liability litigation, there is a substantial body of epidemiological and biological literature regarding the relationship between the exposure and the disease at issue. Think of cigarette smoking and lung cancer, asbestos and mesothelioma, or benzene and acute myeloid leukemia.

While the parties to these disputes frequently disagree about whether the data support a causal relationship between the exposure and outcome at issue — and even more frequently dispute the claim that the exposure caused the outcome in any individual — they still are working from a well-developed base of scientific and medical data. In the case of vaping and COVID-19, where knowledge of the disease is in its infancy, the science has not had time to catch up to the events.

The published epidemiological literature contains very little information regarding a correlation between vaping and the likelihood of developing COVID-19. A single study, published in August, reported that persons aged 13 to 24 who had used vape products at any time were five times as likely to be diagnosed with COVID-19 than similarly-aged persons who had never used vape or tobacco products.[1]

However, the study also reported no statistically significant difference in COVID-19 incidence between persons who had vaped in the past 30 days compared to the control group, and that both sometime vapers and past-30-day vapers were more likely to get tested than controls. Finally, the study did not adjust for factors other than vaping that differ in prevalence between the vaping and control groups.

If such factors are themselves related to the risk of developing COVID-19, they are referred to in the epidemiological literature as confounders. Such confounders can account for some or all of the observed difference in risk between vapers and controls.

The only other epidemiological study we are aware of is one which has not yet been subject to peer review, comparing vaping rates in each U.S. state with COVID-19 incidence and death rates in that state, and finding a positive correlation.[2] This type of study, which does not have data regarding the vaping status of any individual who contracted, or died of, COVID-19, is of limited value in examining causation.

There is considerably more data regarding cigarette smoking and COVID-19 than there is regarding vaping and COVID-19. There are far more cigarette smokers in the world than there are vapers, and patient data is far more likely to include information regarding smoking status than vaping status. Therefore, to date, most claims in the scientific and medical community that vaping increases the susceptibility to, or the severity of, COVID-19 are based on studies of nicotine and/or cigarette smoking, not studies of vaping itself.

These studies have led some researchers to propose mechanisms by which vaping might contribute to progression of COVID-19. In particular, it has been asserted that nicotine increases the expression of an enzyme known as ACE-2, which is found on the surface membranes of cells in the lungs and other organs,[3] through its effect on a nicotinic receptor, known as nAChR-α7, found on certain bronchial cells.[4]

ACE-2 is believed to be the site at which SARS-Cov-2, the virus that causes COVID-19, enters cells in the lung. We are aware of only one study that has compared ACE-2 expression in persons who vape versus non-vaping controls, and that study — which has not yet been peer-reviewed — reported that vapers did not have increased levels of ACE-2.[5]

The remaining studies have not examined whether vaping itself causes the observed effects. Rather, they assert, as one author put it, that, "[g]iven the role of the nicotine receptor, vaping may also lead to the upregulation of ACE2." In effect, these studies assert that a causal relationship between vaping and ACE-2 expression, and possibly to COVID-19, is plausible, but do little to establish such a relationship.

Further, reliance on studies of cigarette smoking to examine vaping and COVID-19 is questionable, not only because vaping differs from smoking, but also because the data from studies investigating whether cigarette smoking increases susceptibility to, or severity of, COVID-19 might best be described as equivocal.

Some studies report a positive correlation between cigarette smoking and the likelihood that COVID-19 infection will progress to severe disease,[6] while others report no statistical association between the two.[7] Still others report that cigarette smokers have a reduced likelihood of disease progression.[8] It is thus not surprising that the scientific literature already contains a substantial body of criticism of the methodologies and conclusions of these various studies.[9]

So how is a court to evaluate a claim like the one in the Juul MDL? The specific allegation in the master complaint is that "JUUL users are … at greater risk of suffering more serious complications if they contract the coronavirus."[10] But the master complaint does not refer to any scientific studies purporting to describe a causal relationship between vaping and the severity of COVID-19.

Rather, the complaint points to (1) a statement by Michael Felberbaum, a U.S. Food and Drug Administration spokesman, who commented in March that "[e]-cigarettes can damage lung cells," and expose people who "smoke and/or vape tobacco or nicotine-containing products" to more "serious complications from COVID-19" — though it should be noted that the FDA subsequently modified this position, stating that it was unknown "whether [vape product] exposure ... increase[s] the risk of COVID-19,"[11] — and (2) a statement from the National Institute on Drug Abuse that COVID-19 posed an "especially serious threat" to persons who vape "[b]ecause [COVID-19] attacks the lungs."[12]

In a courtroom, these assertions must be analyzed not in the context of public health, but of tort law. To establish general causation, a plaintiff must prove that it is more probable than not that an exposure is capable of causing or contributing to the disease in question. A mere showing that the relationship is plausible is legally insufficient.[13]

Further, "[t]o prove general causation, scientists frequently rely on epidemiological data to first establish an association between a chemical and a disease or set of symptoms which they then probe to determine if the association warrants being described as cause-effect relationship."[14] By this standard, assertions like those in the Juul MDL appear to be insufficient to support a viable claim.

There is no epidemiological or toxicological data that might help assess the question of whether it is more likely than not that vaping causes, or increases the severity of, COVID-19. Standing alone, the assertions do not meet the tort law requirement of an in-depth assessment of causality.

The assertions are classic statements of plausibility, not of causation. However, while cases always unfold in real time, in this case, the science is doing so as well. Whether courts will allow cases to proceed, on the theory that as the cases progress the science will as well, remains to be seen.

David Jaroslaw is a partner, Christopher Gismondi is of counsel and Naira Gorovits is a scientific adviser at DLA Piper.

The opinions expressed are those of the author(s) and do not necessarily reflect the views of the firm, its clients or Portfolio Media Inc., or any of its or their respective affiliates. This article is for general information purposes and is not intended to be and should not be taken as legal advice.

[1] Gaiha, S. M., Cheng, J., and Halpern-Felsher, B. (2020), Association Between Youth Smoking, Electronic Cigarette Use, and COVID-19. J. Adolesc. Health, 67(4), 519-523, doi:10.1016/j.jadohealth.2020.07.00ha et al., 2020.

[2] Li, D., Croft, D. P., Ossip, D. J., and Xie, Z. (2020), Are Vapers More Susceptible to COVID-19 Infection?, medRxiv, 2020.2005.2005.20092379, doi:10.1101/2020.05.05.20092379.

[3] Leung, J. M., Yang, C. X., and Sin, D. D. (2020), COVID-19 and nicotine as a mediator of ACE-2. Eur Respir J, 55(6), doi:10.1183/13993003.01261-2020; McAlinden, K. D., Eapen, M. S., Lu, W., Chia, C., Haug, G., and Sohal, S. S, (2020). COVID-19 and vaping: risk for increased susceptibility to SARS-CoV-2 infection? European Respiratory Journal, 56(1), 2001645, doi:10.1183/13993003.01645-2020.

[4] Russo, P., Bonassi, S., Giacconi, R., Malavolta, M., Tomino, C., and Maggi, F. (2020), COVID-19 and smoking: is nicotine the hidden link? Eur Respir J, 55(6), doi:10.1183/13993003.01116-2020.

[5] Lee, A. C., Chakladar, J., Li, W. T., Chen, C., Chang, E. Y., Wang-Rodriguez, J., and Ongkeko, W. M. (2020), Tobacco, but not nicotine and flavor-less electronic cigarettes, induces ACE2 and immune dysregulation, bioRxiv, 2020.2007.2013.198630, doi:10.1101/2020.07.13.198630.

[6] Alqahtani, J. S., Oyelade, T., Aldhahir, A. M., Alghamdi, S. M., Almehmadi, M., Alqahtani, A. S., Quaderi, S., Mandal, S., and Hurst, J. R. (2020), Prevalence, Severity and Mortality associated with COPD and Smoking in patients with COVID-19: A Rapid Systematic Review and Meta-Analysis, PLoS One, 15(5), e0233147, doi:10.1371/journal.pone.0233147; Guo, F. R. (2020), Smoking links to the severity of Covid-19: An update of a meta-analysis, J. Med. Virol., doi:10.1002/jmv.25967; Patanavanich, R., and Glantz, S. A. (2020). Smoking Is Associated With COVID-19 Progression: A Meta-analysis, Nicotine & Tobacco Research, 22(9), 1653-1656, doi:10.1093/ntr/ntaa082; Zhao, Q., Meng, M., Kumar, R., Wu, Y., Huang, J., Lian, N., Deng, Y., and Lin, S. (2020), The impact of COPD and smoking history on the severity of COVID-19: A systemic review and meta-analysis, J. Med. Virol., doi:10.1002/jmv.25889.

[7] Lippi, G., & Henry, B. M. (2020), Active smoking is not associated with severity of coronavirus disease 2019 (COVID-19), Eur J Intern Med, doi:10.1016/j.ejim.2020.03.014; Zheng, Z., Peng, F., Xu, B., Zhao, J., Liu, H., Peng, J., Li, Q., Jiang, C., Zhou, Y., Liu, S., Ye, C., Zhang, P., Xing, Y., Guo, H., and Tang, W. (2020), Risk factors of critical and mortal COVID-19 cases: A systematic literature review and meta-analysis, J. Infect., doi:10.1016/j.jinf.2020.04.021.

[8] Cen, Y., Chen, X., Shen, Y., Zhang, X. H., Lei, Y., Xu, C., Jiang, W. R., Xu, H. T., Chen, Y., Zhu, J., Zhang, L. L., and Liu, Y. H. (2020), Risk factors for disease progression in patients with mild to moderate coronavirus disease 2019 — a multi-centre observational study, Clin. Microbiol. Infect., doi:10.1016/j.cmi.2020.05.041; Miyara, M., Tubach, F., POURCHER, V., Morelot-Panzini, C., Pernet, J., Haroche, J., Lebbah, S., Morawiec, E., Gorochov, G., Caumes, E., Hausfater, P., COMBES, A., Similowski, T., and Amoura, Z. (2020), Low incidence of daily active tobacco smoking in patients with symptomatic COVID-19, Qeios, preprint v3, retrieved from; Petrilli, C. M., Jones, S. A., Yang, J., Rajagopalan, H., O'Donnell, L., Chernyak, Y., Tobin, K. A., Cerfolio, R. J., Francois, F., and Horwitz, L. I. (2020), Factors associated with hospital admission and critical illness among 5279 people with coronavirus disease 2019 in New York City: prospective cohort study, BMJ, 369, m1966, doi:10.1136/bmj.m1966.

[9] Polosa, R., and Caci, G. (2020), COVID-19: counter-intuitive data on smoking prevalence and therapeutic implications for nicotine, Intern. Emerg. Med., doi:10.1007/s11739-020-02361-9; WHO (June 30, 2020), Smoking and COVID-19, retrieved from

[10] In re JUUL Labs Inc. Marketing, Sales Practices, and Products Liability Litigation, MDL 2913 (C.D. Cal.), Amended Complaint April 6, 2020, ¶ 725.

[11] Bloomberg (2020), FDA Shifts Its Covid-19 Stance on Vaping, Smoking Impact, retrieved from

[12] In re JUUL Labs Inc., Amended Complaint, April 6, 2020, ¶726.

[13] Allen v. Pennsylvania Engineering Corp.,102 F. 3d 194, 198 (5th Cir. 1996) (regulatory agencies tasked with making "prophylactic rules governing human exposure" adopt a "preventive perspective" where the "threshold of proof is reasonably lower than that appropriate in tort law, which "traditionally make[s] more particularized inquiries into cause and effect" and requires a plaintiff to prove "that it is more likely than not that another individual has caused him or her harm") (quoting Wright v. Willamette Industries Inc. , 91 F.3d 1105, 1107 (8th Cir.1996)).

[14] Beyer v. Anchor Insulation Co. , 238 F. Supp. 3d 270, 280 (D. Conn. 2017) (citing Federal Judicial Center, Reference Manual on Scientific Evidence 374 (2d ed. 2000)).

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