October 4, 2010

Flu vaccines safe for most allergic children, pediatricians say

With the flu season looming and health officials calling for across-the-board immunization, some parents may wonder just how safe the egg-based flu vaccine is for children with allergies.

Pretty safe, say pediatricians from the Johns Hopkins Children’s Center. Even though the flu vaccine contains egg protein, most children with egg and other food allergies can be immunized safely with a few basic precautions, they say.

An estimated 2 percent to 3 percent of U.S. children are allergic to eggs, but leaving them unprotected against the flu can lead to many unnecessary yet preventable infections and hospitalizations, the Johns Hopkins doctors say. And because many children with food allergies also have asthma, they are at even higher risk for complications from the flu.

“Some parents are understandably concerned about allergic reactions to the flu vaccine and in the past may have opted against it, but the risk of catching the flu far outweighs the risk for an allergic reaction to the vaccine, and even children with egg allergies can be immunized safely,” says Robert Wood, director of Allergy and Immunology at the Johns Hopkins Children’s Center.

Children with established diagnoses of severe egg allergy should not be immunized without consulting a pediatric allergist, Wood cautions. But in most cases, even these children can be vaccinated safely after a skin-prick test with the vaccine itself to gauge the risk for a reaction, he says. Children with suspected yet unconfirmed allergies and those with mild egg allergy usually can be vaccinated in their pediatrician’s office.

Two years ago, Wood and fellow Johns Hopkins pediatrician Neal Halsey provided an approach for immunizing children with known or suspected allergies. Wood and colleagues reported that nearly all allergic children can be safely immunized with a combination of allergy testing and close monitoring in a doctor’s office for a few hours following the injection. Serious allergic reactions to vaccines are extremely rare—one or two cases per million vaccinations, according to some estimates—but when they happen, it is critical for pediatricians to instantly spot them, differentiate them from more benign nonallergic responses and treat them, Wood says. Children who have had one allergic reaction are at high risk for subsequent ones, so pediatricians are encouraged to have a safe immunization plan for these children.

Wood offers the following guidelines to doctors and parents uncertain about vaccine safety in children with previous allergic reactions to vaccines:

First, such children need a workup by a pediatric 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 to detect telltale antibodies against gelatin or egg proteins used in several common vaccines.

Second, pediatricians can use alternative allergen-free forms of a vaccine if available. There is no egg-free version of the flu vaccine. If allergen-free formulations are unavailable, many children can still be vaccinated but should remain under doctor supervision for several hours following the vaccination. 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.

Third, keep in mind that true allergies typically cause immediate reactions, involving the immune system as a whole and occurring within a few minutes to a few hours of vaccination. Symptoms of immediate allergic reactions include hives, swelling, wheezing, coughing, low blood pressure, vomiting and diarrhea, and they can lead to full-blown anaphylaxis, a life-threatening allergic reaction. By contrast, delayed reactions, which occur within days, even weeks after vaccination, are generally benign and are rarely, if ever, dangerous.

Fourth, children with known allergies can be given anti-allergy medications, such as antihistamines and corticosteroids, before vaccination to help ward off or lessen an allergic reaction.

For the first time, health officials this year urge flu vaccination of all children 6 months and older. In previous flu seasons, experts have generally recommended flu vaccines only for those whose medical conditions put them at high risk for complications, including children with asthma, diabetes, heart disease or neurological disorders and those with suppressed immune systems. Pediatricians, however, should continue to make special efforts to vaccinate those at high risk for complications, according to the American Academy of Pediatrics.

Related website

A Parents’ Guide to the Flu, 2010