Eggs can be a problem from a food safety perspective because they provide a nearly ideal growth medium for microorganisms. Eggs have a high level of liquid in them, and are rich in nutrients, especially proteins, that allow for rapid bacterial growth. These characteristics, however troublesome for cooks and chefs, make eggs an excellent medium for the controlled growth of bacteria for vaccine purposes. This also means that anyone with an egg allergy must be cautious about receiving injections.
Egg Allergy
Eggs are one of the eight allergens that account for an estimated 90 percent of all known food allergies in the United States, according to the Food Allergy and Anaphylaxis Network. Their widespread use in baked goods and processed foods makes them an unusually difficult food to avoid. The potential presence of eggs in some vaccines is also a concern.
Growth Medium
A number of growth media are used for producing virus populations under controlled circumstances for vaccines. Two common choices are serum albumen derived from beef blood and human blood cells. A third is egg-derived media, such as chick embryo fibroblasts. Flu vaccines, for example, are commonly grown on an egg-derived medium. Vaccines vary in the degree of risk they represent for an egg-allergic person, so it's best to discuss this with your doctor before getting any injections.
Meruvax and MMR
Meruvax is grown on either human or bovine serum albumen, rather than egg-derived fibroblasts. Therefore, it's not a concern for anyone with an egg allergy. However, most Meruvax is not delivered on its own, but rather as part of a combined measles-mumps-rubella vaccine, known collectively as MMR. The MMR is administered twice during childhood, once at 12 to 15 months and once at 4 to 6 years. Both the measles and mumps portions of the combined vaccine are grown on an egg-derived medium.
Meruvax Safety
The chick fibroblasts that are used as a growth medium for mumps and measles vaccines contain no protein from the albumen, and therefore no egg antigens. This means they can be safely administered even to children who are at risk of anaphylactic shock from eggs, according to the American Academy of Pediatrics. Other vaccines are grown differently, and should be discussed individually with your doctor.
Although egg content is not an issue, there are other safety considerations with Meruvax. Allergic reactions, including anaphylactic shock, are not unknown. Pregnant and nursing women, those with depressed immune systems and those allergic to neomycin should avoid Meruvax.
References
- Food Allergy and Anaphylaxis Network: Egg Allergy
- Food Allergy and Anaphylaxis Network: Other Allergens
- Pediatrics in Review: Egg-Based Vaccines
- Drugs.com: Meruvax II
- Centers for Disease Control and Prevention: Guide to Vaccine Contraindications and Precautions
- Centers for Disease Control and Prevention: Measles, Mumps, and Rubella — Recommendations of the Advisory Committee on Immunization Practices
