MMR Vaccine Names
The MMR vaccine is available in the United States as M-M-R II (manufactured by Merck & Co., Inc.) and PRIORIX (manufactured by GlaxoSmithKline Biologicals), both of which are fully interchangeable for all indications for which MMR vaccination is recommended. 1
Available MMR Vaccine Formulations
Primary MMR Vaccines:
- M-M-R II (Merck & Co., Inc.) - Available in the US since 1978 1
- PRIORIX (GlaxoSmithKline Biologicals) - FDA approved in June 2022 1
Both vaccines contain live attenuated strains of measles, mumps, and rubella viruses that are genetically similar or identical to each other 1.
Composition Details:
- Each dose of M-M-R II contains approximately 0.3 milligrams of human albumin, 25 micrograms of neomycin, 14.5 milligrams of sorbitol, and 14.5 milligrams of hydrolyzed gelatin 1
- PRIORIX is formulated without preservatives and is administered as a subcutaneous injection (the same as M-M-R II) 1
Interchangeability and Administration
The Advisory Committee on Immunization Practices (ACIP) has determined that:
- PRIORIX and M-M-R II are fully interchangeable for all indications 1
- Either vaccine can be used according to the existing MMR recommended schedules 1
- Both vaccines can be administered as a single dose or in a series regardless of which product was used for previous doses 1
Important Clinical Considerations
- Both vaccines are administered subcutaneously 1
- PRIORIX is supplied as a single-dose vial of lyophilized antigen to be reconstituted with the accompanying prefilled syringe of sterile water diluent 1
- A single dose after reconstitution is approximately 0.5 mL 1
- Both vaccines have demonstrated high immunogenicity with seroconversion rates of 95-100% for each component 2
Potential Pitfalls and Contraindications
When administering either MMR vaccine, be aware of these contraindications:
- Genuine hypersensitivity to eggs
- Hypersensitivity to aminoglycoside antibiotics (kanamycin and neomycin) 2
- Additional live virus vaccines not administered on the same day should be separated by ≥4 weeks 1
Availability Benefits
Having two interchangeable vaccines from different manufacturers helps safeguard the U.S. vaccine supply to maintain measles and rubella elimination and mitigate mumps cases and outbreaks 1. This is particularly important given the ongoing need to maintain high vaccination coverage to prevent disease resurgence.