The teenagers had fevers, chest pain, and struggled to breathe. Many coughed up mucus or blood. Some felt nauseous and vomited.

The teens were among the seven patients Boston Children’s Hospital has seen over the past year and a half believed to be suffering from vaping-related lung illness that has recently roiled the country, leaving seven dead and 380 hospitalized.

Suspecting infection, doctors treated the teens with antibiotics, but puzzlingly, symptoms persisted and tests were negative. All the patients needed respiratory support, from oxygen to breathing tubes in the intensive-care unit.

“We thankfully have not lost anybody at Boston Children’s,” said Dr. Alicia Casey, a pediatric pulmonologist. “These are otherwise healthy teens . . . presenting very sick.”

The exploding outbreak, linked to 38 possible cases in Massachusetts, has raised questions about why it’s happening now, when vaping has been popular for years. Officials say the disease has affected people who vaped cannabis, nicotine, or both, and who used both legal and black-market products.

Source: Boston Globe