Among the 107 reports of pre-existing "yeast allergies," 11 reports described probable or possible anaphylaxis after HBV. Four additional cases were described after other vaccines. The majority of vaccinees who met the case definitions and had a history of yeast allergies were female, ages ranged from 10 to 64, and symptom onset ranged from 15 min to 5 h after vaccination. No deaths were reported.