The preparation of recombinant
hepatitis B vaccines involves using cellular cultures of
Saccharomyces cerevisiae, otherwise known as
baker's yeast.
Prior to
vaccine licensure,
clinical trials were performed to address whether residual
yeast proteins in the
vaccines could induce
anaphylaxis, including testing for
IgE anti-yeast
antibody levels. 1-2% of subjects had anti-yeast
IgE antibodies before
immunization, but demonstrated no significant rise in
IgE after
HBV. We searched reports in the
Vaccine Adverse Event Reporting System (VAERS) for those that mentioned a history of
allergy to
yeast and then reviewed the
adverse events described in these reports for potential
anaphylactic reactions. Probable
anaphylaxis was defined as the presence of one or more dermatologic
symptoms and one or more
respiratory,
gastrointestinal, or
cardiovascular symptoms with onset within 4 h of
Hepatitis B vaccination. Possible
anaphylaxis was defined in one of two ways: (1) cases that described dermatologic or
respiratory symptoms (but not both) occurring within 4h of
vaccination; or (2) cases that described one or more dermatologic and/or
respiratory symptoms occurring 4-12 h post
vaccination. 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. The small number of reports to VAERS may be partly due to health care professionals observing current contraindications by not vaccinating
yeast sensitive individuals. Nevertheless,
yeast associated
anaphylaxis after
HBV in sensitized patients appears to be a rare event.
