Because the flu vaccine is grown in chicken eggs, there have traditionally been concerns about the safety of flu shots for people with egg allergies, most of whom are young children.

But today's vaccine has only tiny traces of egg protein, and studies have been showing that kids with egg allergies can be vaccinated without any serious reaction.

In the new study, Canadian researchers followed 367 egg-allergic people, mostly children, who got the flu shot over five years. Almost one-third of them had a history of anaphylaxis after eating eggs - that is, serious allergy symptoms like trouble breathing or a drop in blood pressure.

None of those patients, however, had a serious reaction to the flu vaccine. And only 13 of the 367 had mild "allergy-like" symptoms, like itchy skin or hives, within a day of the jab.

Researchers led by Dr. Anne Des Roches, of Hopital Sainte-Justine in Montreal, report the findings in The Journal of Allergy and Clinical Immunology.