Hundreds of people have become sick from a mysterious vaping-related lung illness and several people have died. But federal health officials say they still don't know what's causing the devastating sickness.

The Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) are investigating a "cluster" of severe lung illnesses that the agencies believe are linked to e-cigarette use. As of Oct. 8, the CDC has identified 1,299 cases in 49 states and the U.S. Virgin Islands. At least 26 people have now died from the illness.

They've also given it a name, though not one that rolls off the tongue: EVALI, which stands for e-cigarette, or vaping, product use associated lung injury.

More than half of the people who have become sick are under the age of 25, with 16% younger than 18. Nearly three-fourths of the patients are male.

The agencies are investigating the exact cause and whether the illnesses are linked to specific devices, ingredients or contaminants. Presently, the cases don't appear to be linked to one product or substance, the agencies said, although they noted that in "most" cases, patients had reported using THC and nicotine.

"I'd like to stress how challenging this situation is, as patients may have been exposed to a variety of products and substances, may not know the contents or sources of these products, and in some instances may be reluctant or too ill to fully disclose all the details of interest," CDC Principal Deputy Director Dr. Anne Schuchat said in a call to the media.

Mitch Zeller, director of the FDA's Center for Tobacco Products, said on the call that the agency's office of criminal investigations had started "parallel investigative efforts." The office is investigating details about the products — where they were purchased, and how they were being used — but the agency isn't planning on prosecuting individual e-cigarette users.

The CDC has urged Americans to stop using e-cigarettes during the investigation, especially those containing THC.

"While this investigation is ongoing, people should consider not using e-cigarette products. People who do use e-cigarette products should monitor themselves for symptoms (e.g., cough, shortness of breath, chest pain, nausea, vomiting, abdominal pain, fever) and promptly seek medical attention for any health concerns," said the CDC in a statement.

The laws around vaping

bottles of flavored vaping liquid With flavors like peach lemonade and butterscotch, no wonder so many young people are attracted to vaping. (Photo: Lindsay Fox [CC BY 2.0]/Flickr)

When e-cigarettes first hit the U.S. in 2007, they were marketed as a safer alternative to traditional cigarettes. But studies have continued to reveal health concerns with the products. Most recently, a comprehensive analysis of peer-reviewed vaping studies published in the journal BMJ found measurable adverse effects on lung health, similar to traditional cigarettes. "No evidence shows that they are safer than other tobacco products," the researchers wrote.

Lung injuries from vaping are likely caused by toxic chemical fumes, say researchers at the Mayo Clinic, who studied lung biopsies from 17 patients who were believed to have vaping-related lung illness. The findings were published in The New England Journal of Medicine.

“All 17 of our cases show a pattern of injury in the lung that looks like a toxic chemical exposure, a toxic chemical fume exposure, or a chemical burn injury,” Dr. Brandon Larsen, a surgical pathologist at the Mayo Clinic in Scottsdale, Arizona, tells The New York Times. “To be honest, they look like the kind of change you would expect to see in an unfortunate worker in an industrial accident where a big barrel of toxic chemicals spills, and that person is exposed to toxic fumes and there is a chemical burn in the airways.”

In addition to continued research, the rash of illnesses and a rise in young people vaping has prompted several states and the federal government to call for a ban on flavored e-cigarettes. Officials hope that banning the flavors that are appealing to young people will cut back on the use of e-cigarettes.

The Trump administration announced in mid-September that it would ban the sale of most flavored e-cigarettes. The ban, which is expected to take several weeks to enact, would include mint and menthol, which are popular flavors for young people.

Michigan became the first state to ban flavored e-cigarettes in early September. Not long after, New York Gov. Andrew Cuomo announced an emergency executive action to ban the sale of flavored e-cigarettes in the state. A New York court temporarily halted the ban just a day before it was due to take effect, Reuters reports. The state says it will also be cracking down on stores that sell to underage buyers, with the possibility of criminal penalties. In October, Washington state's board of health approved a 120-day temporary ban on flavored vaping products, reports The Seattle Times. A similar temporary ban was approved days earlier in Rhode Island, according to the Providence Journal.

San Francisco became the first city to ban e-cigarette sales after city officials voted in June to ban stores from selling the items and online retailers from delivering to city addresses, according to CNN. Mayor London Breed signed the ordinance a few days later. San Francisco's ban is notable not only for the city's early action but also because it's home to leading e-cigarette manufacturer Juul Labs.

America's largest retailer has also taken a stand on vaping. On Sept. 20, Walmart announced it would stop selling e-cigarettes.

"Given the growing federal, state and local regulatory complexity and uncertainty regarding e-cigarettes, we plan to discontinue the sale of electronic nicotine delivery products at all Walmart and Sam's Club US locations," the company said in a statement. "We will complete our exit after selling through current inventory."

What is the FDA's role in this?

The actions highlight what e-cigarette opponents and health advocates say is the FDA's failure to act on the issue, points out CNN. Officials from San Francisco, New York and Chicago criticized the FDA in a March letter for allowing e-cigarettes to remain for sale without undergoing a review on their impact on public health.

"San Francisco has never been afraid to lead and we're certainly not afraid to do so when the health and lives of our children are at stake," City Attorney Dennis Herrera said in that letter. "By law, before a new tobacco product goes to market, the Food and Drug Administration is supposed to conduct a review to evaluate its impact on public health. Inexplicably, the FDA has failed to do its job when it comes to e-cigarettes. Until the FDA does so, San Francisco has to step up."

The FDA banned e-cigarette sales to children under 18 in May 2016, but other regulation has been slippery. According to the FDA, currently e-cigarettes that are marketed for therapeutic purposes (like the cessation of smoking) are regulated by the FDA Center for Drug Evaluation and Research (CDER). The FDA finalized a rule that went into effect in August 2016 that broadens the administration's authority to include e-cigarettes.

The FDA has stated its intent to issue a proposed rule that would extend the agency's authority to products that meet the statutory definition of "tobacco product," which would include e-cigarettes.

"Before this final rule, these products could be sold without any review of their ingredients, how they were made, and their potential dangers," Zeller explained in an earlier statement. "Under this new rule, we're taking steps to protect Americans from the dangers of tobacco products, ensure these tobacco products have health warnings, and restrict sales to minors."

Editor's note: This story has been updated with new information since it was published in September 2019.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

What we know about vaping-related lung illness
Health officials don't know exactly what is causing the lung illness that's linked to e-cigarettes and vaping.