Audrey Pirri, 16, had been terrified of vomiting since she was a toddler. She worried every time she shared a meal with family or friends, restricting herself to “safe” foods such as pretzels and salad that wouldn’t upset her stomach, if she ate at all. She was afraid to ride in the car with her brother, who often got carsick. She fretted for hours about an upcoming visit to a carnival or stadium anywhere with lots of people and their germs.