It appears that children with egg allergies have little to fear from the flu vaccine, whether it comes in a needle or nasal spray.

This Tuesday in The BMJ, researchers published their results from a cohort study of nearly 800 children with a preexisting egg allergy and/or asthma who were given an live attenuated influenza vaccine (LAIV) via nasal spray. They found that though nine volunteers (1.2 percent) experienced mild symptoms indicative of a small allergic reaction, there was no evidence of a widespread allergic response, including anaphylaxis, afterwards. “LAIV did not cause any systemic allergic reactions in this cohort of young people with egg allergy,” the authors concluded. “[Additionally] LAIV seems to be well tolerated in young people with a diagnosis of asthma or recurrent wheeze, provided that lower respiratory symptoms are well controlled.”

No Egg On The Face

Most versions of the flu vaccine start off their life inside a hen egg, and thus often contain trace amounts of the protein ovalbumin, found primarily in egg whites. While injectable vaccines have long been considered safe for people with egg allergy, the researchers opted not to count their chickens before they hatched when it came to a nasal spray version recommended for people under the age of 18 called Fluenz Tetra® (Tetra referencing the four flu strains it offers protection against).

The 779 children in the study, ages 2 to 18, were recruited from 30 allergy centers throughout the United Kingdom from September 2014 to Febuary 2015. After receiving a dose of Fluenz Tetra®, they were observed for a half hour, were followed up with over the telephone 3 days later, and in the case of children with a history of asthma or recurrent wheeze, were brought in for examination four weeks later. The acute symptoms experienced by nine participants ranged from an irritated nose to contact rash, but were “mild, self limiting, and occurred within 30 minutes of immunization with LAIV.”

Though there were no serious adverse events reported, there were possible delayed symptoms of allergy in at least 221 participants, primarily involving the upper and lower respiratory tract. The subsequent examination of 394 children with an asthma history, however, revealed no difference in the level of lower respiratory tract symptoms in the four weeks before and after vaccination. The researchers noted that the children recruited for the study are more likely to have more severe egg allergies than the general population, indicating that the vaccine’s potential allergy risk would be even more mild in a real world setting.

Coupled with an earlier study conducted by the same researchers of 282 children (though that study involved a type of vaccine without detectable amounts of ovalbumin), the researchers are confident that the flu spray is perfectly safe for most egg-sensitive folk, save possibly for children who previously received intensive care after a severe allergic reaction to eggs.

“As with all settings providing vaccination, facilities should be available and staff trained to recognise and treat anaphylaxis,” they advised, however.

Source: Turner P, Southern J, Andrews N, et al. Safety of live attenuated influenza vaccine in young people with egg allergy: multicentre prospective cohort study. The BMJ. 2015.