The Centers for Disease Control and Prevention has confirmed 805 of the more than 1,000 cases of lung injury illnesses under investigation across the nation.
That's a jump from the 530 cases the CDC reported last week, reflecting a fast-moving and evolving epidemic that's touched almost every state in the country. State health departments have confirmed to NBC News that more than 1,000 cases are being investigated.
On Thursday, three new deaths were confirmed, one by Moses Cone Hospital in Greensboro, North Carolina, another by the Mississippi State Department of Health, and a third by the Oregon Health Authority.
"People should stop vaping immediately," said Dr. Dean Sidelinger, state health officer for the state of Oregon, in a statement.
"If you vape, whether it's cannabis, nicotine or other products, please quit. These are addictive substances, and we encourage people to take advantage of free resources to help them quit."
Eleven other deaths have also been reported: two in California, two in Kansas, and one each in Florida, Georgia, Illinois, Indiana, Minnesota, Missouri and Oregon. All together, 14 deaths have been reported.
Only three states — Alaska, New Hampshire and Rhode Island — have not reported any cases so far. On Thursday, the Oklahoma State Department of Health reported its first case, in a person under age 18.
"We are just now starting to see some of the dangerous health outcomes of vaping," Dr. Thomas Dobbs, Mississippi state health officer, said in a release. "There is still so much we don’t know. It’s uncharted territory."
All patients have reported a history of vaping — either THC, nicotine or something else — and many suffer from a combination of similar symptoms that look like a form of pneumonia: coughing, trouble breathing, chest pain, extreme fatigue, vomiting and diarrhea.
Patients often require mechanical assistance breathing, and some have been admitted to hospital intensive care units.
The deluge of cases has federal health investigators working around the clock to learn more about what it is about vaping that's causing these illnesses.
So far, only the act of vaping itself has been the common link, though many patients have reported vaping products containing THC, the active ingredient in marijuana.
On Wednesday, the acting head of the Food and Drug Administration, Dr. Ned Sharpless, told a House committee his agency "should have acted sooner" to contain the e-cigarette epidemic that's now spun out of control among youth in particular.
Last week, researchers reported the teen vaping rate has doubled since 2017. The annual Monitoring the Future survey included data from more than 40,000 students in middle school and high school.
At least a quarter of 12th graders and more than 20 percent of high school sophomores said they'd vaped within the past month. And one in 11 kids in the eighth grade also admitted to vaping.
Several states — Massachusetts, Michigan, New York and Rhode Island — have enacted various bans on flavored e-cigarettes in response to both the increase in youth vaping, as well as the nationwide vaping illness outbreak.