Development, Formulation and Administration
The component viral strains of MMR vaccine were developed by propagation in animal and human cells. The live viruses require animal or human cells as a host for production of more virus.
For example, in the case of mumps and measles viruses, the virus strains were grown in embryonated hens' eggs and chick embryo cell cultures. This produced strains of virus which were adapted for the hens egg and less well-suited for human cells. These strains are therefore called attenuated strains. They are sometimes referred to as neuroattenuated because these strains are less virulent to human neurons than the wild strains.
The Rubella component, Meruvax, is propagated using a human cell line (WI-38, named for the Wistar Institute) derived in 1961 from embryonic lung tissue.
| Disease Immunized | Component Vaccine | Virus Strain | Propagation Medium | Growth Medium |
|---|---|---|---|---|
| Measles | Attenuvax | Enders' attenuated Edmonston strain | chick embryo cell culture | Medium 199 |
| Mumps | Mumpsvax | Jeryl Lynn (B level) strain | ||
| Rubella | Meruvax II | Wistar RA 27/3 strain of live attenuated rubella virus | WI-38 human diploid lung fibroblasts | MEM (solution containing buffered salts, fetal bovine serum, human serum albumin and neomycin, etc.) |
MMR II is supplied freeze-dried (lyophilized) and contains live viruses. Before injection it is reconstituted with the solvent provided.
The MMR vaccine is administered by a subcutaneous injection.The second dose may be given as early as one month after the first dose. The second dose is a dose to produce immunity in the small number of persons (2–5%) who fail to develop measles immunity after the first dose. In the U.S. it is done before entry to kindergarten because that is a convenient time.
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