Canadian Immunization Guide
Seventh Edition - 2006

[Previous] [Table of Contents] [Next]

Part 2
Vaccine Safety and Adverse Events Following Immunization

Anaphylactic Hypersensitivity to Egg and Egg-Related Antigens

• General considerations
• Summary of guidelines for vaccination of egg- or chicken-allergic individuals
• Selected references

Changes since the publication of the 2002 Canadian Immunization Guide include the following: 1) no special precaution when administering measles, mumps, and rubella (MMR) vaccine to egg-allergic individuals; 2) information on the new rabies vaccine (RabAvert^® ), which is derived from virus grown in chick embryo cell culture; and 3) chicken allergy as a contraindication to vaccination with the yellow fever vaccine.

General considerations

In this chapter, egg or chicken allergy is defined as an IgE-mediated hyper-sensitivity causing symptoms like, but not limited to, urticaria, swelling of the mouth and throat, difficulty breathing or hypotension. Chicken allergy refers to allergy to chicken meat as opposed to allergy to feathers.

Egg allergy is one of the most common food allergies of childhood, with a prevalence of 1%-3% in children under 3 years of age. As most children outgrow their egg allergy, the prevalence in adulthood is much lower. Isolated chicken allergy is a very rare condition.

Vaccines that contain small quantities of egg protein can cause hypersensitivity reactions in some people with allergies to eggs. The likelihood of such reactions occurring varies considerably among vaccines. The yellow fever vaccines are prepared from virus grown in chick embryos and are the most likely to cause allergic reaction in egg- or chicken-allergic individuals. Allergic reactions can also occur to vaccines against influenza, which are prepared from viruses grown in embryonated eggs. In contrast, the MMR vaccine viruses most widely used in Canada and one of the rabies vaccines (RabAvert^® ) are grown in chick embryo cell culture. The final vaccine products may contain trace quantities of egg proteins, but the amount is not felt to be enough to cause an allergic reaction, especially for MMR. Some extra precautions are still recommended for RabAvert^®. Egg proteins are not involved in the manufacturing process of the other rabies vaccine (Imovax^® Rabies).

MMR vaccine

Anaphylaxis after measles vaccination is rare. It has been reported both in people with anaphylactic hypersensitivity to eggs and in those with no history of egg allergy. In some of these instances it is hypersensitivity to gelatin that is responsible for the anaphylactic reaction. As well, allergy to other components of the vaccine, such as neomycin, has been hypothesized but not proven. The minute quantity of egg proteins contained in the MMR vaccine seems to be insufficient to cause an allergic reaction in egg-allergic people.

Several studies have reported uneventful routine MMR immunization in egg-allergic people and in those with positive MMR skin tests, whereas others have reported occasional adverse reactions despite the use of MMR skin testing and graded challenge vaccination. Therefore the use of skin testing with MMR vaccines in egg-allergic individuals is no longer recommended.

The largest published review of the literature provides data on 1227 egg-allergic patients who received the MMR vaccine as a usual single dose. Only two had any symptoms suggesting an allergic reaction, and they were from the same case report, whereas in better studies no patient reacted. These combined data indicate that 99% of children who are allergic to egg can safely receive the vaccine (95% confidence interval (CI) 99.41%-99.98%).

Four of the best studies from this review of the literature are summarized below.

• Fasano et al (1992) studied 140 children whose double-blind placebo-controlled food challenges to egg were positive or who had a convincing history of recent anaphylaxis to egg ingestion and a positive skin test to eggs. Seventy-one children were immunized prospectively and 69 children had already received the MMR vaccine. None had any reaction to the vaccine.
• James et al (1995) prospectively evaluated the administration of MMR vaccine to 54 children with positive skin test to eggs and either a positive food challenge to egg or convincing history of severe or recent anaphylactic reaction to egg. None had any reaction to the vaccine.
• Aickin et al (1994) described 242 children with documented allergic reaction after the ingestion of egg and positive skin test to egg. None had any reaction to the vaccine.
• Freigang et al (1994) described 500 children with convincing history of egg allergy and positive skin test to egg. None had any reaction to the vaccine.

In view of the cumulative data indicating the safety of MMR immunization in people with a history of anaphylactic hypersensitivity to hens' eggs and the lack of evidence of the predictive value of MMR skin testing, the National Advisory Committee on Immunization (NACI) does not recommend routine MMR skin testing or any special precaution in these individuals. As for all vaccines, NACI recommends immunization by personnel with the capability and facilities to manage adverse events following immunization such as anaphylaxis.

Rabies vaccine

Immunization with rabies vaccine obtained by viruses grown in chick embryo cell culture (RabAvert^® ) is probably safe in egg-allergic individuals because the vaccine contains only a minute quantity of egg proteins; however, no safety data exist. An alternative vaccine, if available, should be used in egg-allergic individuals. If an alternative vaccine is not available, post-exposure prophylaxis should be administered with strict medical monitoring in facilities where emergency treatment of anaphylaxis is available. For pre-exposure vaccination when no alternative vaccine is available referral to an allergy specialist prior to vaccination is recommended, as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization.

Influenza vaccine

Allergic reactions have been reported in patients with egg allergy receiving the influenza vaccine. In the few studies evaluating immunization with influenza vaccine in egg-allergic children, allergic reactions ranged from 0%-40%.

Most influenza vaccines probably contain only a very small amount of egg proteins, but manufacturers do not report the egg content of their influenza vaccine. In some studies in which investigators have determined the egg content of some influenza vaccines, it was found that the egg protein content varied by several logarithmic factors from manufacturer to manufacturer and from year to year.

Egg-allergic individuals should not be routinely vaccinated with the influenza vaccine. Of these individuals, those who are at risk of the complications of influenza should be evaluated by an allergy specialist, as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization. If such an evaluation is not possible, the risk of an allergic reaction to the vaccine must be weighed against the risk of influenza disease.

Yellow fever vaccine

The yellow fever vaccine has the greatest likelihood of containing sufficient amounts of egg or chicken proteins to cause an allergic reaction in egg- or chicken-allergic individuals. There have been several reports of anaphylactic reactions to the yellow fever vaccine in egg- or chicken-allergic individuals but no studies have been done in which the vaccine was administered to such individuals in order to monitor for the reaction. The yellow fever vaccine should not be routinely administered to egg- or chicken-allergic individuals. Referral to an allergy specialist is recommended, as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization.

Summary of guidelines for vaccination of egg- or chicken-allergic individuals

• Individuals should be asked about allergy to egg prior to vaccination with influenza vaccine, yellow fever vaccine and the rabies vaccine RabAvert^®.
• Individuals should be asked about allergy to chicken prior to vaccination with yellow fever vaccine.
• Prior egg ingestion should not be a prerequisite for immunization with egg-containing vaccine.
• Atopic diseases are not a contraindication to immunization with egg-containing vaccine.
• Egg allergy is not a contraindication to immunization with MMR. People with these allergies may be immunized in the routine manner without prior testing.
• Influenza vaccines that are prepared from viruses grown in embryonated eggs should not be given to egg-allergic individuals unless the risk of the disease outweighs the small risk of a systemic hypersensitivity reaction. Referral to an allergy specialist is recommended, as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization.
• Yellow fever vaccines should not be given to egg- or chicken-allergic individuals unless the risk of the disease outweighs the small risk of a systemic hypersensitivity reaction. Referral to an allergy specialist is recommended, as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization.
• When no alternative vaccines are available for egg-allergic individuals, post-exposure vaccination with RabAvert^® should be performed in facilities where treatment for anaphylaxis is available. For pre-exposure vaccination when no alternative vaccine is available, referral to an allergy specialist is recommended as vaccination might be possible after careful evaluation, skin testing and graded challenge or desensitization.
• Re-immunization with MMR, yellow fever, influenza or rabies vaccine is contraindicated in an individual with a previous anaphylactic reaction to that vaccine. Referral to an allergy specialist is recommended to find out which component of the vaccine was responsible for the allergic reaction

Selected references

Aickin R, Hill D, Kemp A. Measles immunisation in children with allergy to egg. British Medical Journal 1994;309:223-25.

Fasano MB, Wood RA, Cooke SK et al. Egg hypersensitivity and adverse reactions to measles, mumps and rubella vaccine. Journal of Pediatrics 1992;120(6):878-81.

Freigang B, Jadavji TP, Freigang DW. Lack of adverse reactions to measles, mumps and rubella vaccine in egg-allergic children. Annals of Allergy 1994;73:486-88.

Herman JJ, Radin R, Schneiderman R. Allergic reactions to measles (rubeola) vaccine in patients hypersensitive to egg protein. Journal of Pediatrics 1983;102(2):196-99.

James JM, Burks AW, Roberson PK et al. Safe administration of the measles vaccine to children allergic to eggs. New England Journal of Medicine 1995;332(19):1262-66.

Kelso JM, Yunginger JW. Immunization of egg-allergic individuals with egg- or chicken-derived vaccines. Immunology and Allergy Clinics of North America 2003;23(4):635-48.

Zeiger RS. Current issues with influenza vaccination in egg allergy. Journal of Allergy and Clinical Immunology 2002;110(6):834-40.

[Previous] [Table of Contents] [Next]