The safety of the H1N1 influenza A vaccine in egg allergic individuals

Abstract

The safety of H1N1 vaccine is unknown in egg allergic (EA) recipients. To establish the safety of administering H1N1 vaccine and to evaluate the predictability of H1N1 skin testing in EA patients. In a controlled, prospective trial, H1N1 skin testing and vaccination was compared between EA patients (n = 105) and non-EA controls (n = 19). Those with negative H1N1 skin test results received a full H1N1 dose; those with a positive skin test result received a graded challenge (10%, 90%). Booster vaccine, if required, was given as a single dose from a different lot without prior testing. Prick and intradermal test results were positive in 3 (2.4%) of 124 and 41 (33.1%) of 124 study participants, respectively. Forty-one individuals received a 2-step graded vaccine challenge, including 13 of 25 with a history of egg anaphylaxis. No significant allergic reactions resulted from either method of vaccination or from subsequent booster doses. All study participants received the H1N1 vaccine without significant allergic reactions. Skin testing is unnecessary and does not predict vaccine tolerance. All study participants who received a graded challenge tolerated a single dose booster from a different, untested lot, including 7 individuals with a history of egg-induced anaphylaxis. We recommend administration of H1N1 vaccine to EA children without prior skin testing or graded challenge dosing.