Flu shot safe even for those with egg allergy
DEAR DOCTOR: My pharmacist recently told me I could get a flu shot, even though I have an egg allergy. Is this true?
DEAR READER: As the current flu season illustrates, the influenza virus accounts for thousands of illnesses and deaths each year. The number of deaths attributed to influenza over the past 40 years has ranged from 3,349 to 56,000 a year; the average annual death rate is about 23,000.
For the majority of flu shots, the influenza virus is created by injecting it into fertilized chicken eggs, where it multiplies. The fluid within the egg is eventually removed, inactivated and used for the injectable vaccine. Although this fluid is saturated with the virus, it also contains egg protein. That’s potentially a problem because many people are allergic to eggs. Some of these allergies manifest as hives, but others are life-threatening, with severe shortness of breath and a rapid decline of blood pressure (called an anaphylactic reaction). Thus, the primary worry about the use of eggs to make the vaccine has been that the vaccine could lead to major allergic reactions.
Because of the risk, manufacturers for years have been trying to
reduce the amount of egg protein within the vaccine — and they’ve succeeded.
Multiple studies have assessed the impact of giving the flu vaccine to people with egg allergies. Overall, these studies identified no anaphylactic reactions. One study did show that, in people with egg allergies, about 1 in 100 people experienced minor allergic reactions, which were treated with an antihistamine. Most notable perhaps is that people with a history of anaphylactic reactions to egg did not have reactions when given the vaccine.
Based on this data, both the Centers for Disease Control and Prevention and the American Academy of Pediatrics have stated that the vaccine can be given to people with egg allergies of any severity. They suggest, however, that to address the theoretical possibility of a severe reaction, people giving the vaccine should have medications and resuscitative equipment on hand.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.
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