Safe Vaccines Still Possible For Most Vaccine-Allergic Children

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Safe Vaccines Still Possible For Most Vaccine-Allergic Children

Main Category: Immune System / Vaccines

Article Date: 02 Sep 2008 - 3:00 PDT

With close monitoring and a few standard precautions, nearly all children

with known or suspected vaccine allergies can be safely immunized, according

to a team of vaccine safety experts led by the s Hopkins Children's

Center. Writing in the September issue of Pediatrics, the multicenter

research team offers pediatricians a step-by-step tool for quickly

identifying children with allergic reactions to vaccines, and a much-needed

guide, they say, to safely immunize those who are allergic.

Serious allergic reactions to vaccines are extremely rare - one or two per

million vaccinations, according to some estimates - but when they happen,

such episodes can be serious, even life-threatening, making it critical for

pediatricians to instantly spot true allergic reactions and differentiate

them from more benign nonallergic responses, investigators say. It is also

crucial that pediatricians design a safe immunization plan for children with

confirmed vaccine allergies. Children who have had one allergic reaction are

believed to be at a higher risk for future reactions, typically more serious

than the first.

" We cannot reiterate enough that the vaccines used today are extremely safe,

but in a handful of children certain vaccine ingredients can trigger serious

allergic reactions, " says Wood, M.D., lead author on the paper and

chief of pediatric Allergy and Immunology at Hopkins Children's. " For the

most part, even children with known allergies can be safely vaccinated. "

Given recent outbreaks of vaccine-preventable infections like measles, mumps

and whooping cough in the United States, and measles and polio overseas, it

is essential to safely vaccinate as many children as possible, investigators

say.

Combing through available evidence on vaccine safety and allergies, the

Hopkins-led team developed a sequence of instructions - an algorithm - that

prompts physicians one step at a time on how to evaluate and immunize

children with known or suspected vaccine allergies.

The guidelines are intended for doctors and parents who are uncertain about

vaccine safety in children who have already had or are at high risk for

having allergic reactions to vaccines.

In such cases, the Hopkins-led group advises a workup by an allergist,

including skin prick testing-a prick on the skin or an injection under the

skin with a small dose of vaccine or the suspected allergen from the

vaccine-or blood tests that would detect the presence of characteristic

antibodies that patients develop to allergens, such as antibodies to gelatin

or egg proteins used in several common vaccines.

In many cases, allergic children can be vaccinated using alternative forms

of a vaccine that are free of the allergen. Even if allergen-free

formulations are unavailable, many children can still be vaccinated and

remain under physician supervision for several hours after vaccination.

Another option is testing the child to check for immunity. If blood tests

show the child has already developed protective antibodies, it may be OK, at

least temporarily, to withhold further doses of the vaccine, researchers

write.

" Vaccines save lives, and parents should know that children who have had

allergic reactions after a vaccine are likely to have developed protection

against infection as a result of the vaccination, " says investigator Neal

Halsey, M.D., an infectious disease specialist at Hopkins Children's, and

professor of International Health at the s Hopkins University Bloomberg

School of Public Health.

" Most children who have had an allergic reaction after a vaccine can still

be vaccinated against other diseases safely and some can receive additional

doses of vaccines they might have reacted to, " Halsey adds.

Many children with known vaccine allergies who have low levels of protective

antibodies and require more doses can be vaccinated safely under the

guidelines. In some cases, children with known allergies can be given

antiallergy medications, such as antihistamines and corticosteroids, before

vaccination to help ward off or lessen the allergic reaction. For a

step-by-step guide to vaccine administration in children with known or

suspected vaccine allergy, see the full text of the article at

http://pediatrics.aappublications.org/future/122.3.shtml.

Immunizations of children with known vaccine allergies should always be

administered under medical supervision in a clinic equipped to treat

life-threatening allergic reactions or in a hospital intensive-care unit.

Patients can usually go home after an hour or two if they have no adverse

reactions.

True allergies typically cause immediate reactions, involving the immune

system as a whole that occur within a few minutes to a few hours of

vaccination. By contrast, delayed reactions, which occur within days, even

weeks after vaccination, are generally benign and are rarely, if ever,

dangerous.

Symptoms of immediate allergic reactions include hives, swelling, wheezing,

coughing, low blood pressure, vomiting, diarrhea, and can lead to full-blown

anaphylaxis, a life-threatening allergic reaction.

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Article adapted by Medical News Today from original press release.

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The research was funded by the Centers for Disease Control and Prevention.

Co-investigators on the research: Melvin Berger, M.D. Ph.D., University

Hospitals of Cleveland; Dreskin, M.D. Ph.D., University of Colorado;

nna Setse, M.D. M.P.H., s Hopkins University Bloomberg School of

Public Health; Renata Engler, M.D., Walter Army Medical Institute;

Cornelia Dekker, M.D., Stanford University School of Medicine. The Clinical

Immunization Safety Assessment Network, consisting of six medical research

centers with expertise in immunization safety, was part of the study.

Conflict of interest disclosure for Hopkins investigators: Halsey has received

research support from vaccine manufacturer Wyeth and is a consultant for vaccine

manufacturers GlaxoKline and Merck.