An Epidemic Supplanted by a Pandemic: Vaping-related Illness and COVID-19

Yoo Mee Shin, MD; Daniel P. Hunt, MD; Joyce Akwe, MD, MPH


South Med J. 2022;115(1):8-12. 

In This Article

E-cigarettes or Vaping Product Use–Associated Lung Injury

Although e-cigarettes were touted to be much safer than conventional cigarettes, there is substantial evidence of e-cigarette-associated lung injury. The respiratory system has direct exposure to vapor and smoke from e-cigarettes, causing direct irritation to both upper and lower airways.[23,32,33] As e-cigarette and vaping product use has increased, there has been a growing number of cases of a new disease process known as e-cigarette or vaping product use–associated lung injury (EVALI). In 2019, the Wisconsin Department of Health Services and the Illinois Department of Public Health investigated a series of patients with lung injury related to e-cigarette or vaping use. From this investigation, 98 patients from Wisconsin and Illinois were identified who were suspected to have EVALI. They found that respiratory and gastrointestinal symptoms were common, occurring in 97% and 77% of patients, respectively. Most of the patients had shortness of breath, cough, chest pain, nausea, vomiting, and diarrhea. A majority of patients had constitutional symptoms, including subjective fevers and chills. EVALI is a diagnosis of exclusion.[34] The patient must have used vaping within the past 90 days, other etiologies must be eliminated, and chest imaging findings must be abnormal.[35] As part of the evaluation for EVALI, patients obtained chest X-ray and/or chest computed tomography (CT). They found that more than 80% of patients had an abnormal chest x-ray and 100% of patients had abnormal findings on chest CT.[36] On CT scans, EVALI manifests as acute lung injury similar to hypersensitivity pneumonitis with multifocal ground glass opacities, often with organizing consolidation, diffuse alveolar damage, and a small centrilobular nodular pattern.[37,38] Other less common forms of lung injury, including acute eosinophilic pneumonia and diffuse alveolar hemorrhage, also have been reported.[35]

As of February 2020, there have been more than 2800 cases of EVALI reported to the CDC, with approximately 68 deaths attributed to this illness.[39] Cases of acute eosinophilic pneumonia, organizing pneumonia, acute respiratory distress syndrome, and hypersensitivity pneumonitis have been described as well.[40] No single substance has been found responsible for EVALI or EVALI-associated deaths, but the main ingredients that seem to cause lung injury are tetrahydrocannabinol (THC), nicotine, and vitamin E acetate (which is an additive in THC products).[30,31,40,41] The CDC found that 82% of EVALI patients reported using THC-containing products. A majority of these patients obtained their products from informal sources, such as friends, family, in-person dealers, or online dealers. In addition, the CDC found that among those patients who reported using nicotine-containing products (57%), a majority obtained their products through commercial sources, such as medical and recreational dispensaries, vape shops, or smoke shops. THC-containing products obtained from informal sources contain traces of vitamin E acetate, which is believed to contribute to EVALI.[30] One study looking at the bronchoalveolar lavage fluid showed vitamin E acetate was present in 945 of EVALI patients but none in the healthy controls.[13] This suggests that vitamin E acetate may be a primary cause of EVALI. Nevertheless, patients who report using nicotine-only products also have been diagnosed as having EVALI, raising concerns that components other than vitamin E acetate may stimulate lung injury.[30] More studies are needed to pinpoint the cause.

The mechanism of lung injury from e-cigarettes is not completely understood. As e-cigarette liquid is heated, it aerosolizes heavy metals such as tin, iron, nickel, lead, and chromium and produces tobacco-specific N-nitrosamines, polycyclic aromatic hydrocarbons, and volatile organic compounds.[42,43] Propyleneglycol and glycerol are the major ingredients used as the delivery system for e-cigarettes. Exposure to propyleneglycol mist may occur from smoke generators used in nightclubs, theaters, and aviation emergency training. Wieslander et al studied the health effects from occupational exposure to propyleneglycol and found that exposure to propyleneglycol for as little as 1 minute results in upper airway irritation in nonasthmatic subjects.[43] A few participants in this study developed a cough and slight reduction in forced expiratory volume in 1 second and forced vital capacity.[43] A minute amount of heavy metals has been found in some e-cigarette vapors.[44] It is unclear how these small amounts of heavy metals affect the lung mechanics over a long period of time.[7]

Another area of lung health interest with e-cigarettes is the potential effects on the immune system of the lung. Reidel et al studied sputum samples in e-cigarette users and found that e-cigarette users had increased oxidative stress–related proteins, increased levels of innate defense proteins, increased immune response proteins, and a change in the composition of airway mucus.[45] A study from Greece found that the use of e-cigarettes for even 5 minutes caused an increase in airflow resistance, a decrease in exhaled nitric oxide, and an increase in oxidative stress.[46] Even a brief exposure to e-cigarettes caused altered lung function on a cellular level. There were changes in gene expression that could increase inflammation, decrease host defense mechanisms, and increase pro-tumorigenic signals.[46]