Post-marketing
surveillance of immediate allergic reactions: polygeline-based versus
polygeline-free pediatric TBE vaccine.
Zent O,
Hennig R.
Chiron Vaccines, Clinical Research and Medical
Affairs, P.O. Box 1630, D-35006 Marburg, Germany.
olaf_zent@chiron.com
Scattered cases of immediate allergic
reactions occurred in the nineties after widespread use of the original
(polygeline-based) pediatric tick-borne encephalitis (TBE) vaccine and
were reported to Pharmacovigilance, Chiron Vaccines. Although, still
indicating a very rare frequency of about two cases per 100,000 doses
sold, the benefit/risk assessment resulted in its withdrawal from the
market in early 1998. An intensive evaluation revealed that polygeline
used as a vaccine stabilizer was the most probable cause of the reported
allergic reactions. Consequently, an improved pediatric TBE vaccine,
free of polygeline and other protein-derived vaccine stabilizers, was
developed. A post-marketing surveillance analysis covering the first two
vaccination seasons after the introduction of this new pediatric TBE
vaccine in early 2002 reveals a very low reporting rate of immediate
allergic reactions post immunization (within the range as noted for
other widely used vaccines for childhood immunization), i.e., 0.08-0.24
cases per 100,000 doses sold depending on case definition and medical
assessment. In conclusion, this analysis provides post-marketing
surveillance evidence that the change in the vaccine formulation, with
regards to the potential risk of immediate allergic reactions, has led
to an intended improvement in the vaccine's safety profile.