Pool V, Braun MM, Kelso JM, et al. Prevalence of anti-gelatin IgE antibodies
in people with anaphylaxis after measles-mumps rubella vaccine in the United
States. Pediatrics. 2002 Dec;110(6):e71.
Rare MMR vaccine reactions often due to gelatin
Last Updated: 2002-12-26 10:00:06 -0400 (Reuters Health)
NEW YORK (Reuters Health) - Severe allergic reactions to the
measles-mumps-rubella (MMR) vaccine are rare, but when they occur they may
oftentimes be tied to the gelatin used in the vaccine, a US study confirms.
Researchers found that out of a small number of people believed to have suffered
serious allergic reactions to the MMR vaccine, about one quarter showed
hypersensitivity to gelatin. Gelatin is used as a heat stabilizer in the
manufacture of a number of vaccines, the study authors note in the December
online issue of the journal Pediatrics.
In most cases, reactions to MMR vaccination are fairly mild and include a rash
or fever. Rarely, serious allergic reactions marked by symptoms such as
breathing problems, hives and rapid heartbeat occur. Immediate, severe
reactions have sometimes been attributed to egg allergy because the MMR vaccine
is cultured (grown) in chick embryo cells and may contain bits of egg proteins.
But research has indicated that most MMR reactions are not associated with egg
allergies.
Gelatin, on the other hand, has been implicated in vaccine reactions in recent
years. The US Centers for Disease Control and Prevention (CDC) advises that
anyone who has ever had a life-threatening allergic reaction to gelatin not get
the MMR.
In the new study, a team led by Dr. Vitali Pool of the CDC in Atlanta, Georgia
looked at data from a national registry of adverse vaccine reactions. Between
1991 and 1997, there were 168 "probable" or "possible" serious allergic
reactions to MMR vaccination. The investigators were able to get blood samples
from 22 of these people, who ranged in age from 15 months to 33 years. They
then compared the samples with blood taken from 27 individuals with no history
of serious MMR reaction.
They found that 27% of those with MMR reactions had antibodies to gelatin in
their blood, indicating they were allergic. No one in the other group had these
antibodies, according to the report.
"Results from this study support the hypothesis that (allergic reactions) after
MMR vaccines can in some cases be attributable to hypersensitivity to gelatin,"
Pool's team writes.
They advise that anyone with a history of severe reaction to a gelatin-containing
vaccine be tested for antibodies to gelatin and other potential allergens before
getting another dose of any gelatin-containing vaccine.
As for the roughly three quarters of MMR-reaction patients who did not show
sensitivity to gelatin, the cause of their reactions remains unclear, according
to the researchers. They call for more research to unearth other causes of
allergic reactions to vaccination.
SOURCE: Pediatrics 2002;110:e71.
Copyright © 2002 Reuters Limited.