Each fall, you can count on the seasonal flu to rear its ugly head. In 2019, about 38 million people in the United States got sick with the flu, and 22,000 died, according to the Centers for Disease Control and Prevention (CDC). The best way to protect yourself from getting sick is by getting a flu shot.
But, if you're allergic to eggs, you may have been cautioned against it. But why eggs? The most common way flu vaccines are made is via an egg-based manufacturing process. That means candidate vaccine viruses (CVVs) are first grown in eggs and then injected into fertilized hen eggs and left to incubate for several days. This allows the virus to replicate. Then the fluid from the eggs containing the virus is harvested to create the flu vaccine. So most types of influenza vaccines contain a small amount of egg protein, which may trigger an allergic response from people with egg allergies.
So should people with egg allergies avoid getting annual flu shots? Not necessarily.
An estimated 2 percent of children are allergic to eggs, but about 70 percent of them outgrow the condition by the time they reach age 16. When someone with an egg allergy eats an egg, their immune system goes into attack mode against the proteins in the whites and/or yolks of the egg. Their immune system then sends out a barrage of chemicals to defend itself, according to the American College of Allergy, Asthma & Immunology. This battle between allergens and chemicals — most notably histamine — triggers allergy symptoms, which can range from a mild rash to life-threatening anaphylaxis.
This doesn't mean people with egg allergies shouldn't get flu shots. While that used to be the case, the CDC now recommends that people with a history of egg allergies, regardless of the severity, receive any licensed, recommended and age-appropriate influenza vaccine. This decision is based on studies of both the nasal spray vaccine and flu shot in both people with and without egg allergies. The rate of anaphylaxis after all vaccines is 1.31 per 1 million doses given. That's super low.
The CDC does recommend people with a history of severe allergic reactions to eggs (considered anything besides hives) be vaccinated in a medical setting such as a hospital, medical clinic, health department or doctor's office, by a health care provider trained to recognize and manage an allergic response just as a precaution.
Originally Published: Mar 29, 2011