How to diagnose gelatin allergy (vaccine ingredient)?

Overdiagnosis of vaccine allergy is a major public health problem http://buff.ly/1tI9y44

Vaccines that contain gelatin:

- Influenza (Fluzone, Sanofi Pasteur), Influenza (FluMist, MedImmune Vaccines, Gaithersburg, Maryland)
- Measles, Mumps, Rubella (MMRII, Merck, Whitehouse Station, New Jersey), Measles, Mumps, Rubella,
- Varicella (ProQuad, Merck), Varicella (VARIVAX, Merck)
- Rabies (RabAvert, Novartis, Emeryville, California)
- Typhoid Vaccine Live Oral Ty21a (VIVOTIF, Berna, Coral Gables, Florida)
- Yellow Fever (YF-VAX, Sanofi Pasteur),
- Zoster (ZOSTAVAX, Merck)

How to diagnose gelatin allergy (vaccine ingredient)?

Proceed with the following steps:

- check sIgE to both bovine and porcine gelatins (they are extensively cross-reactive but occasionally there may be disparate results)

- if sIgE is negative, perform a prick skin tests to gelatin (dissolve 1 teaspoon (5 g) of any sugared gelatin powder (for example Jell-O) in 5 mL of normal saline) to determine whether or not the patient is allergic to gelatin

- consider an intradermal test. If both a prick (full-strength) and ID skin tests (diluted 1:100) are negative, it is hard to imagine that the reaction was IgE mediated.

For subsequent vaccination, have a discussion with the parents regarding the risk of vaccination versus the risk of remaining unvaccinated and consider vaccination in graded doses under observation (For a vaccine where the full dose is 0.5 mL, give the following doses at 15-minute intervals as tolerated: 0.05 mL 1:10 dilution, 0.05 mL full-strength, 0.1 mL full-strength, 0.15 mL full-strength, 0.2 mL full-strength) perhaps with pretreatment with an antihistamine.

References:

Allergic reaction to Menactra and Varivax. AAAAI Ask the Expert, 2013 http://bit.ly/12zIxNA
2014 update: Influenza Vaccine and Egg Allergy: Nearing the End of an Evidence-based Journey http://buff.ly/1tHY0wd

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