Also known as: ovalbumin, egg albumin
Egg Protein (Ovalbumin)
Sourced from FDA-approved package inserts (DailyMed). Last verified: 2026-07-07.
What It Is & Why It's in Vaccines
Residual egg protein (primarily ovalbumin) from the embryonated chicken eggs used to grow certain influenza and yellow fever vaccine viruses. Most egg protein is removed during purification; trace amounts may remain.
Not deliberately added — residual from the egg-based manufacturing process for influenza (most inactivated influenza vaccines), yellow fever, and some other vaccines grown in embryonated chicken eggs. Cell-culture-based and recombinant influenza vaccines (e.g., Flucelvax, Flublok) do not use eggs and contain no egg protein.
Dose-in-Context
Per-Dose Quantity
≤1 mcg per dose for most current influenza vaccines (highly purified); older formulations or less-purified products may contain more. FDA/USP limit: ≤1.2 mcg ovalbumin per dose.
Reference Comparison
An egg contains approximately 4 grams (4,000,000 mcg) of protein. The ≤1 mcg in a highly purified influenza vaccine represents approximately 0.000025% of the protein in one egg.
Source: CDC. Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2025–26 Influenza Season. MMWR Recomm Rep. Current edition.
Route-of-Administration Note
Injected route. Egg protein hypersensitivity is primarily a systemic IgE-mediated food-allergy phenomenon. The CDC and ACIP currently state that individuals with egg allergy of any severity may receive any licensed, recommended, age-appropriate influenza vaccine without additional precautions beyond standard observation — this represents a 2023 update from previous more restrictive recommendations based on accumulated safety data.
Documented Adverse Effects
Multiple large studies have demonstrated that egg-allergic individuals — including those with a history of severe anaphylaxis to egg ingestion — can safely receive inactivated influenza vaccines with standard observation, without the need for allergy specialist referral, graded dosing, or extended observation that was previously recommended. The trace quantities of residual ovalbumin in current purified influenza vaccines are below the threshold for triggering IgE-mediated reactions in egg-allergic individuals.
Yellow fever vaccine — which contains higher residual egg protein than current influenza vaccines — still carries an egg-allergy precaution. Egg-allergic individuals should be evaluated by an allergist before receiving yellow fever vaccine.
Vaccines Containing Egg Protein (Ovalbumin)
MMR — PRIORIX (GlaxoSmithKline Biologicals)
Contains no gelatin — relevant for gelatin allergy. Residual ovalbumin possible from chick-embryo manufacture.
Influenza — Fluzone Quadrivalent (Sanofi Pasteur)
Always check vial type: preservative status differs between single-dose and multi-dose presentations.
Yellow Fever — YF-VAX (Sanofi Pasteur)
ⓘ Methodology Disclaimer: Ingredient lists are sourced from official FDA-approved package inserts for the specific branded products named on each vaccine page. Formulations can change between manufacturing lots and over time — always verify against the current package insert before making a clinical decision. The presence of a substance in a vaccine does not by itself indicate harm; toxicology is dose-, route-, and context-dependent. Comparisons to reference exposure levels are provided with their sources where available, and are approximate — see the cited source for full methodology.