The most widely used influenza vaccines are grown in eggs, so for decades, anyone with an egg allergy was advised to either get vaccinated in a controlled setting, such as an allergist’s office, or skip it altogether.
Although the two leading professional groups for allergists made a strong statement that adults and children with egg allergies no longer need to fear the influenza vaccine, getting these folks to accept the vaccine might take awhile, according to experts.
Abundance of Data
“There’s some measurable egg protein called ovalbumin in influenza vaccines that are grown in eggs, so the concern was logical, but interestingly, it has always been theoretical,” said John Kelso, MD, an allergist at Scripps Clinic in San Diego, and a co-author of a revised practice parameter released by the American Academy of Allergy, Asthma & Immunology and the American College of Allergy, Asthma, and Immunology. “There’s an abundance of data showing the vaccine is safe even among severely egg-allergic patients, so we’re going that next step and saying you don’t even need to ask somebody if they’re allergic to eggs before you give them a flu shot.”
The 2017 practice parameter declared that any version of the vaccine—inactivated influenza vaccine (IIV) or live-attenuated influenza vaccine (LAIV)—is safe for all patients with egg allergies (Ann Allergy Asthma Immunol 2018;120[1]:49-52). Furthermore, no special precautions are required, such as skin testing the vaccine on egg-allergic patients before administering it.
With the start of a new influenza season, some infectious disease experts are welcoming the new practice parameter on vaccination. “We immunize about a third of the total population each year that we would like to reach. We use about 150 million doses of vaccine. We need to double that,” said William Schaffner, MD, a professor of infectious diseases at the Vanderbilt University School of Medicine, in Nashville, Tenn., and the medical director of the National Foundation for Infectious Diseases.
Acceptance
However, widespread acceptance of the vaccine’s safety won’t happen overnight, Dr. Schaffner predicted, because the fear of egg allergies is so embedded in the minds of physicians and patients that warnings are still prevalent on consent forms and other documentation that accompanies flu vaccinations. “It will take some persuasion by practitioners to encourage adults and parents of young children who have avoided getting the vaccination,” he told Infectious Disease Special Edition.
The updated practice parameter stemmed from three large studies published since 2013. They involved a total of 955 children, including more than 400 who had a history of allergic reactions to eating eggs. They were all safely vaccinated with LAIV, according to the practice parameter (Ann Allergy Asthma Immunol 2018;120[1]:49-52).
The new recommendations do not apply to the yellow fever vaccine, which is the only other vaccine with measurable amounts of ovalbumin. Another caveat is that anyone who has previously suffered a severe allergic reaction to any vaccine—regardless of their egg allergy status—should be evaluated by an allergist before subsequent vaccination. Those reactions are rare, however, occurring with about one in 1 million administered doses, according to Dr. Kelso.
The recommendations highlight similar guidelines released earlier by a number of other health organizations, including the CDC and the American Academy of Pediatrics, but practicing allergists said the validation from their professional groups was significant. “We were the ones that had been skin testing the flu vaccine in egg-allergic people. But we questioned whether it was really needed,” said Catherine Monteleone, MD, an allergy and immunology specialist at Rutgers Robert Wood Johnson Medical School in New Brunswick, N.J. “The studies show the vaccines are safe, even in people who have had serious reactions to eggs, and that’s a very powerful statement.”
Dr. Schaffner reported financial relationships with Dynavax, Merck, Pfizer, Seqirus, Shionogi and SutroVax. Drs. Kalso and Monteleone reported no relevant financial relationships.