H1N1 Vaccine May Be Safe for Patients with Egg Allergies

Providers can skip precautionary measures when giving egg-allergic children the H1N1 Influenza A vaccine—including those with a previously severe reaction, according to a new study published in the Annals of Allergy, Asthma & Immunology.

In a controlled study, 19 non-egg allergic patients and 105 egg-allergic pediatric patients, 25 of whom had a history of egg-induced anaphylaxis, all received the vaccine without developing an immediate or serious reaction to the primary or booster shots.

According to the study’s lead author, Matthew J. Greenhawt, MD, MBA, of the University of Michigan Health System, there were no differences between those who received the vaccine as a full dose and those who received it in two stages. A preliminary skin test to the vaccine, which was performed for all study participants and used to determine the vaccination method, was found to not be predictive of symptom development or vaccine tolerance.

“This offers good evidence that administering H1N1 as a single, full dose without pretesting or graded challenge is safe and well tolerated in any type of egg-allergic patient, including those with prior egg-induced anaphylaxis,” said Greenhawt in a press release.

The pandemic of the H1N1 Influenza A virus in 2009-10 led to an urgent need to provide the vaccination, prompting re-evaluations on the safety of administering egg-containing immunizations to egg-allergic children and adults.

In the past, egg-allergic individuals were advised to not get the H1N1 vaccine or seasonal Trivalent Influenza Vaccine (TIV) — which are both grown on embryonated chicken eggs – out of fear they would trigger an allergic reaction because both contain egg protein.

Participants received their immunization between Oct. 15, 2009, and Feb. 4, 2010, at University of Michigan allergy clinics. A questionnaire was distributed prior to vaccination to gather information on an individual’s egg allergy history, such as the age of onset and past seasonal influenza vaccination.

According to the study, 83 of 124 patients recorded a negative skin test result and received a full vaccine dose, while the 41 who tested positive received a 2-step graded dose. A history of egg anaphylaxis was not found to increase the odds of a positive skin test.

“Although these results are from a relatively small study population, they suggest that it is unnecessary to withhold the vaccine from patients with a history of egg-induced anaphylaxis,” said study senior author Georgiana Sanders, MD, MS, clinical assistant professor of internal medicine, and pediatrics and communicable diseases.

Providers asked the 110 children who were younger than 10 years to return at a minimum of 4 weeks later for a booster shot because of recommendations from the CDC. The 99 who returned were given the shot without prior skin testing.

All 124 participants received the vaccine without developing an immediate or serious reaction to the primary or booster shots. Researchers reported post-vaccination symptoms, excluding flulike illness, in equal frequency in both those with and without egg allergies.

To access the study, click here.

Based on the findings of this study, would you recommend the H1N1 vaccination to patients with egg allergies, or is it too risky?