Also known as: rHA, recombinant human albumin, HSA
Human Serum Albumin (Recombinant)
Sourced from FDA-approved package inserts (DailyMed). Last verified: 2026-07-07.
What It Is & Why It's in Vaccines
Recombinant human albumin (rHA) is a synthetic version of the most abundant protein in human blood plasma. In older vaccine formulations, human serum albumin was sourced from donated human blood; current products use recombinant DNA technology (produced in yeast or other expression systems) to eliminate the theoretical risk of blood-borne pathogen transmission.
Stabilizer — albumin prevents surface adsorption of antigens to the vial/container walls (a phenomenon called 'surface losses'), maintaining accurate dosing. It also acts as a cryoprotectant and prevents protein aggregation during freeze-drying and storage.
Dose-in-Context
Per-Dose Quantity
≤0.3 mg per dose in products that list it (e.g., M-M-R II). Human blood contains approximately 40 grams of albumin per liter — a 0.3 mg vaccine dose represents less than 0.001% of the albumin in a single mL of the recipient's own blood.
Reference Comparison
The recombinant human albumin in current vaccines is structurally identical to endogenous human albumin. It is not immunogenic in humans (it is recognized as 'self' by the human immune system). This is fundamentally different from bovine or other animal-derived stabilizers, which can provoke an immune response.
Source: DailyMed package insert: M-M-R II.
Route-of-Administration Note
Injected route. Human albumin is a normal plasma protein; injected albumin distributes into the intravascular compartment and is gradually catabolized with a half-life of approximately 15–20 days — identical to endogenous albumin.
Documented Adverse Effects
Recombinant human albumin has no documented adverse effects at vaccine stabilizer quantities. Older plasma-derived human albumin products carried theoretical infectious disease risk; current recombinant products eliminate this concern entirely.
Individuals with genuine human albumin allergy — an exceedingly rare condition — could theoretically react to even recombinant albumin. No specific cases have been documented in the vaccine context.
Vaccines Containing Human Serum Albumin (Recombinant)
ⓘ 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.