A recent study published in Pediatrics shows that when given in small, graded doses, flu vaccines made from chicken embryos are safe for most children with egg allergies. The study also found that skin test done prior to vaccination, which in the past have been used to test a egg allergenic child’s potential for reaction, are unnecessary–saving time and money for both patients and vaccine providers. Erica Chung, MD, a Children’s hospital staffer and co-author of the study recently took time to explain her findings for Thrive.
From the 1918 “Spanish flu,” to the 1957 “Asian flu,” and more recently, the “swine flu,” the influenza virus continues to emerge as a major public health concern. But with the development of medical advancements like the influenza vaccine program, we have seen a drop in the number of hospitalization and clinic visits during influenza season. Because the vaccine is developed in chicken embryos, however, there is some hesitancy about vaccinating egg-allergic children, despite the vaccine’s many benefits.
Although developed in chicken embryos, the influenza vaccine itself contains a very small amount of egg protein. Typically, egg-allergic children receive skin testing with the influenza vaccine to determine if they are likely to have a serious adverse reaction to the vaccine. The group at the Children’s Hospital Boston Allergy Program found the skin testing to be time consuming and possibly unreliable in identifying children who will tolerate the vaccine.
Starting in the 2006 to 2007 influenza season, the program removed the vaccine skin test from its protocol. Egg-allergic children, who did not have serious anaphylactic reactions to egg, were given the influenza vaccine in small, graded doses without receiving a vaccine skin test beforehand. These children received one-tenth of the vaccine dose and, if tolerated without serious reactions, received the remaining nine-tenths dose.
My colleagues and I examined the rate of vaccine adverse reaction during the periods both with and without a vaccine skin test. Of the 56 children who received the vaccine skin test prior to the influenza vaccine, 95% tolerated the vaccine without serious adverse events. Of the 115 children who received the vaccine without skin testing, 97% tolerated the vaccine without serious reactions. Removing the vaccine skin test did not affect the rate of adverse reactions. Egg-allergic children were just as likely to tolerate the influenza vaccine with the skin test as compared to no skin test. It is important to note that our study did not include children with serious anaphylactic reactions to egg.
Of the adverse reactions documented, the majority were localized reactions, such as redness and swelling at the site of injection. The systemic reactions included wheezing and rash. There were no serious anaphylactic reactions.
By removing the skin test from the vaccine protocol, we can expedite the process of influenza vaccine administration for both patients and providers. Furthermore, we can eliminate the number of egg-allergic children who are denied the influenza vaccine due to a falsely-positive skin test. Overall, by eliminating the skin test prior to vaccination we can vaccinate and protect more egg-allergic children from influenza infections. Parents of egg-allergic children should speak with their physician about the influenza vaccine.