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Allergy Myth Busters: Egg allergy and flu vaccine

It seemed to make sense:  Influenza vaccine is made in chicken-embryo cells so there are small amounts of egg protein (called ovalbumin) in the vaccine.  Therefore, egg-allergic patients could have reactions to influenza vaccine and special precautions should be taken.  Right?  Wrong!

Medical Studies: Where is the proof?

  • 27 published studies involving over 4100 egg-allergic individuals (over 500 with anaphylaxis after ingesting eggs) who received the flu vaccine were reviewed.  Results:  No serious reactions (low blood pressure “shock” or breathing problems)!  Minor reactions were no different between groups (egg allergic vs egg non-allergic).  Source: https://www.ncbi.nlm.nih.gov/pubmed/23021881
  • Studies using the “live” attenuated influenza vaccine Flumist® (which is no longer recommended as of 2016 due to lack of effectiveness) also showed no anaphylaxis and minor allergic reactions were no different between egg-allergic patients compared to non-egg allergic individuals.   The amount of egg ovalbumin in live attenuated form was less than 0.24 micrograms per dose (1/4 that of the killed influenza virus vaccine).

What does the CDC (Center for Disease Control and Prevention) recommend?

  • In the U.S., CDC and its Advisory Committee on Immunization Practices have updated their guidelines on egg allergy and receipt of influenza (flu) vaccines starting in 2016.  Based on the new recommendations, people with egg allergies no longer need to be observed for an allergic reaction for 30 minutes after receiving a flu vaccine.  Should it be required, people with a history of severe allergic reaction to egg (any symptom other than hives) can now be vaccinated in any setting, under the supervision of any health care provider who is able to recognize and manage severe allergic conditions.  There is no need for skin testing with the vaccine or splitting the dose.  Source:  https://www.cdc.gov/flu/protect/vaccine/egg-allergies.htm
  • What about in Canada?  Since 2014, Canadian Vaccine Guidelines have recommended influenza vaccine to individuals with egg allergy and there has not been an uptick in numbers of reports of allergic reactions.

What causes reactions to the influenza vaccine?

  •  Thimerasol: this preservative can lead to redness and swelling at the injection site.  Thimerasol contains a small amount of ethylmercury which is different than methylmercury (methylmercury builds up in fish and because it lasts much longer than ethylmercury can lead to toxicity).  Thimerasol is only used in multi-dose vials (single dose vials do not contain thimerasol).  Thimerosal was taken out of childhood vaccines in the United States in 2001.  Measles, mumps, and rubella (MMR) vaccines do not and never did contain thimerosal. Varicella (chickenpox), inactivated polio (IPV), and pneumococcal conjugate vaccines have also never contained thimerosal.
  • Unclear. Even the completely egg-free influenza vaccine known as Flublock® which was available in 2013 has led to reactions.  From 2013 to 2016, there were 88 reports of allergic reactions (10 anaphylaxis) reported through VAERS (Vaccine Adverse Event Reporting System).  Other symptoms were fatigue, fever, headache and muscle aches.  Source: https://www.ncbi.nlm.nih.gov/pubmed/28886946

Who should receive the flu vaccine?

  • Infants, children and adolescents: The American Academy of Pediatrics recommends all children over 6 months old should receive the influenza vaccine every year.  These recommendations for 2017-2018 season can be found at:  https://www.ncbi.nlm.nih.gov/pubmed/28870977
  • High Risk Groups
    • Pregnant women (and women up to 2 weeks after delivery): the vaccine can decrease risks of developing flu for mother and infant for several months after birth.
    • Children younger than 5 years old but especially children younger than 2 years old
    • Adults 65 years of age and older
    • Residents of nursing homes and long term care facilities
    • American Indians and Alaskan Natives
    • People who have medical conditions including:
      • Asthma or other chronic lung diseases (COPD, Cystic Fibrosis)
      • Heart disease (coronary artery disease, heart failure and congenital heart disease)
      • Neurologic Diseases (seizures, cerebral palsy, strokes, muscular dystrophy, spinal cord injury, moderate to severe developmental delay, mental retardation, brain disorders)
      • Blood disorders (sickle cell disease)
      • Metabolic disorders (mitochondrial disorders)
      • Other disorders: diabetes, kidney and liver disorders
      • Weakened immune system (HIV or AIDS, cancer, those on chronic oral steroids)
      • People younger than 19 years old on long-term aspirin therapy
      • People with extreme obesity (body mass index [BMI] of 40 or more)

Who should NOT receive a flu vaccine?

  • A person who previously had a severe allergic reaction to flu vaccine, regardless of the component suspected of being responsible for the reaction.
  • People who have a moderate-to-severe illness with or without a fever (should wait until they recover to get vaccinated)
  • People with a history of Guillain-Barré Syndrome (a severe paralytic illness) that occurred after receiving influenza vaccine and who are not at risk for severe illness from influenza.

Is the influenza vaccine perfect? 

  • No, even when the flu strains in the vaccine are well matched with the circulating viruses, the risk of illness is only reduced by 40 to 60%.  However, the flu vaccine is still the most effective prevention strategy currently available.
  • Can you get the flu from the killed influenza vaccine? No (it is killed).

What are the risks of NOT giving the influenza vaccine?

  • Average of 294,000 people admitted to the hospital each year in the U.S.
  • Average of 21,000 hospitalizations for children under 5 years old in the U.S.
  • Average of 23,000 deaths each year in the U.S.
  • Average of 124 childhood deaths each year in the U.S.

At Family Allergy & Asthma Care of Montana, we give you the facts on influenza, the latest recommendations and encourage you to make the right choice for you and your family!  Thanks to Doug Paauw, MD at the University of Washington in Seattle, WA for his inspiration on writing about “Medical Myths.”

This information is solely for informational purposes and not intended as a substitute for consultation with a medical professional.

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