The number of lung illnesses linked to vaping has risen again across the United States, showing no sign of slowing. On Thursday, the Centers for Disease Control and Prevention reported 1,299 cases of the severe lung injuries in 49 states, plus Washington, D.C., and the U.S. Virgin Islands.

Alaska remains the only state untouched by the epidemic.

The new CDC case count is 219 more than what was reported last week. However, state health departments tell NBC News that more than 1,650 cases have either been confirmed or are under investigation.

The weekly increases in cases include both newly diagnosed patients and cases in which patients have since recovered, but whose illnesses have now been determined to have been vaping-related.

Patients in 22 states have died from the illness. Health officials previously made grim predictions that the death toll will continue to rise.

Indeed, late Thursday afternoon, the Indiana State Department of Health announced an additional two deaths had been confirmed. That brings the national total to 29.

Deaths have occurred in people ranging from ages 17 and 75; the median age of patients who've died is 49.

Young men vaping THC at risk

It's becoming increasingly clear that young men who vape THC are at particular risk, although cases have been reported among women and those who say they only vape nicotine.

According to the CDC:

70 percent of patients are male

80 percent of patients are under age 35

76 percent of patients report vaping THC.

THC is marijuana's active ingredient that gives users a high. The Food and Drug Administration has tested more than 440 vape product samples obtained from patients, though no single product or substance has been linked to all of the cases. In addition, some products sent to the FDA for testing contained little to no e-liquid.

The surge in cases has prompted several states to enact various e-cigarette bans. The Washington State Board of Health, for example, approved an emergency stoppage on the sale of flavored vaping products, including mint and menthol, effective Thursday.

That ban will last for 120 days.

It did not come without protest, however. Board members heard from people who credited e-cigarettes with helping them quit smoking regular tobacco, well known to cause diseases that kill almost a half million Americans a year.

But addiction experts say that it's the flavors that hook young people on nicotine in the first place.

A 2018 report from the National Academies of Sciences, Engineering and Medicine determined e-cigarettes are a gateway to tobacco addiction for teenagers and young adults, for whom e-cigarette use has grown dramatically in recent years.

Thursday, the CDC published findings from researchers who scoured the parking lots and grounds at 12 high schools around the San Francisco Bay area, looking for trash leftover from e-cigarette use.

Almost all of the waste contained evidence of the Juul brand of e-cigarettes with flavors other than tobacco. Most discarded Juul flavor pods were mint or menthol. However, it must be noted, there is no evidence to suggest that Juul e-cigarettes are the cause of the current deluge of vaping-related illnesses.

Among the few marijuana vaping waste items discovered included "packaging from high-potency pineapple- and lemon-flavored cannabis oil concentrate vaporizer cartridges," the researchers wrote.

San Francisco was the first major U.S. city to approve a ban on the sale of all vaping devices, and a similar measure is before the Los Angeles City Council. San Francisco's rule will take effect in January.

Massachusetts, Michigan, Montana, New York and Rhode Island have all approved varying measures of electronic cigarette bans.

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