MR and MMR Vaccines

What Are These Vaccines?

Vaccine Strains (MMR)

• Measles: Schwartz or Moraten substrains of the Edmonston B strain
• Mumps: Jeryl Lynn strain
• Rubella: RA 27/3 strain

Immunization Schedule

India - National Immunization Schedule (NIS 2020)

International / MMR Schedule (USA/Global)

• 1st dose: 12-15 months of age
• 2nd dose: 4-6 years of age (at school entry), but can be given earlier if interval is at least 28 days after the first dose

• Children 6-11 months traveling internationally or during an outbreak: give MMR, but this dose is not counted - 2 valid doses still required from 12 months onward
• Catch-up for adolescents: given at 11-12 years if only 1 prior dose received (Red Book 2021)

Efficacy

• A single dose provides >95% lifelong immunity against measles
• Two doses give near-complete protection
• Herd immunity requires >93% vaccination coverage - below this, outbreaks can occur (Medical Microbiology 9e)

Contraindications

• Pregnancy (avoid conception for 1 month after vaccination)
• Severe immunosuppression (e.g., hematologic malignancy, congenital immunodeficiency)
• History of anaphylaxis to a prior MMR dose or to vaccine components (neomycin, gelatin)

• Children 1-13 years: CD4+ percentage <15%
• Adolescents ≥14 years: CD4+ count <200/mm³

Precautions

• Recent receipt of antibody-containing blood products (within 11 months) - delay vaccination
• Moderate or severe acute illness with or without fever
• History of thrombocytopenia or thrombocytopenic purpura
• Tuberculin skin test: can be done before or on the day of MMR; if not, postpone by 4-6 weeks (measles vaccination temporarily suppresses tuberculin reactivity)
• High-dose corticosteroids (≥2 mg/kg/day or ≥20 mg/day prednisone for ≥14 days): wait at least 4 weeks after stopping before vaccinating

Common Adverse Effects

• Low-grade fever (5-15% of recipients), 7-12 days after vaccination
• Mild rash (measles-like)
• Joint pain/arthralgia (mainly rubella component, more in adult women)
• Thrombocytopenic purpura (rare, ~1 in 30,000)
• MMRV only: increased risk of febrile seizures in 12-23 month-olds compared to MMR + varicella given separately

Adults Who Need MMR

• Unvaccinated adults, especially those of childbearing age lacking rubella immunity
• Students in post-secondary educational settings
• Healthcare personnel
• International travelers
• Two doses recommended for high-risk adults; one dose for other unvaccinated adults

Important Points

• A dose given before 12 months of age is NOT counted - 2 valid doses still required starting from 12 months
• MMR can be given to breastfeeding mothers without danger to the infant
• MMR should be given at least 2 weeks before planned immunoglobulin (IG) or blood product administration
• If IG is given within 14 days after MMR, the vaccine must be repeated after the appropriate interval
• Egg allergy is NOT a contraindication (reactions are unlikely)
• During outbreaks, a 3rd dose of mumps-containing vaccine may be recommended for individuals in high-risk settings (colleges, universities)