The annual influenza vaccination protects against seasonal flu viruses. For many years, the safety of the flu shot for individuals with an egg allergy was a common concern due to the historical method of vaccine production. Extensive research and new manufacturing technologies have substantially changed these recommendations. An egg allergy should no longer prevent a person from receiving the protection offered by the flu vaccine.
Why Egg Protein is in Some Flu Vaccines
The traditional method for producing many influenza vaccines has been used for over 70 years. This process involves growing the influenza virus inside fertilized chicken eggs, also known as embryonated eggs. The manufacturer injects the live virus into the egg, allowing it to replicate rapidly. After replication, the fluid containing the virus is harvested and purified to produce the vaccine.
This egg-based process is effective for mass production but results in trace amounts of egg protein, specifically ovalbumin, remaining in the final vaccine. Although purification removes most of the protein, the residual quantity historically concerned individuals with severe egg allergies. This minuscule amount of egg protein was the root cause of precautions against vaccinating egg-allergic individuals with standard flu shots.
Current Guidelines: Getting the Flu Shot If You Have an Egg Allergy
Recent guidelines from major health organizations, such as the Advisory Committee on Immunization Practices (ACIP), state that virtually all people with an egg allergy can safely receive any licensed influenza vaccine. This recommendation applies regardless of the severity of the person’s previous allergic reaction to eggs. Studies consistently show that egg-allergic individuals are not at an increased risk of severe allergic reactions to egg-based flu vaccines.
The amount of residual egg protein in most egg-based vaccines is extremely low, often less than one microgram per dose. This quantity is significantly below the threshold needed to trigger a reaction in most allergic individuals. Therefore, no special precautions are required for individuals whose only reaction to eggs has been hives. They can receive the standard flu shot in any setting where vaccines are routinely administered.
If an individual has a history of a severe allergic reaction to eggs (defined as anything more serious than hives), the recommendation is slightly modified. These individuals can still receive any licensed flu vaccine appropriate for their age and health status. The vaccination should occur in a medical setting, supervised by a healthcare provider capable of recognizing and managing a severe allergic reaction. This supervision is a measure of reassurance and preparedness, reflecting the general standard for administering any vaccine.
Available Non-Egg Based Vaccine Options
For individuals who still have concerns about egg-based vaccines, alternatives manufactured using different technologies completely eliminate the use of eggs in production. These are often referred to as “egg-free” vaccines. One type is the recombinant influenza vaccine, which is synthetically created and does not require a virus grown in eggs. This vaccine is manufactured by genetically modifying a cell line to produce the specific hemagglutinin protein that stimulates the immune response.
Another option is the cell-based influenza vaccine, where the flu virus is grown in cultured mammalian cells instead of chicken eggs. This method avoids the potential for egg-adapted changes in the virus and results in an egg-free vaccine. Both recombinant and cell-based vaccines are approved for use in the United States and are suitable for anyone who qualifies based on age and health status. These non-egg options provide an alternative for people with severe egg allergies or those who prefer modern production methods.
Safety Protocols During and After Vaccination
While the risk of an allergic reaction to the flu shot is low for egg-allergic individuals, standard safety protocols are in place for administering any vaccine. Providers must be prepared to recognize and treat acute hypersensitivity reactions. This requires having the personnel and equipment, including epinephrine, immediately available. This preparedness is a requirement for all vaccine administration settings, not just for egg-allergic patients.
Following vaccination, no observation period is specifically mandated solely because of an egg allergy. However, providers are generally advised to observe all patients for 15 minutes after any vaccine administration. This recommendation is primarily to decrease the risk of injury should a person experience syncope, or fainting, a common non-allergic reaction to injections. For those with a history of severe egg reactions, the clinical supervision provides an extra layer of reassurance.