The Boston Globe’s STAT reports this afternoon that

The Centers for Disease Control and Prevention [“CDC”] reported a rising number of cases of mysterious pneumonias linked to vaping on Friday. Now, the agency reports 450 people from 33 states and one U.S. jurisdiction have been affected. 

Three deaths have been confirmed, authorities said, and another is being investigated. 

The New England Journal of Medicine and CDC’s online journal, Morbidity and Mortality Weekly Report coordinated the release of case reports and case findings from Illinois and Wisconsin, Utah, North Carolina and California. While the descriptions of the cases were remarkably similar, it is not currently clear why young vapers — the majority of cases are young men — are developing severe pneumonias.

Here’s a link to the CDC’s press release on this investigation.  The CDC recommends

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. Regardless of the ongoing investigation, people who use e-cigarette products should not buy these products off the street and should not modify e-cigarette products or add any substances that are not intended by the manufacturer. E-cigarette products should never be used by youth, young adults, pregnant women, or adults who do not currently use tobacco products.