Is the MMRV (Measles, Mumps, Rubella, and Varicella) vaccine safe as the first dose in a 3-year-old?

Safety of MMRV as First Dose in a 3-Year-Old

For a 3-year-old child, either MMR vaccine and varicella vaccine administered separately or MMRV vaccine may be used for the first dose, but unless the parent specifically requests MMRV, separate MMR and varicella vaccines are recommended due to a slightly increased risk of febrile seizures with MMRV in children under 48 months. 1

Age-Based Recommendations for MMRV Administration

First Dose at Age 12-47 Months (Includes 3-Year-Olds)

• For children aged 12-47 months receiving their first dose of measles, mumps, rubella, and varicella vaccines:
  • Either MMR + varicella vaccines (as separate injections) or MMRV vaccine may be used
  • CDC recommends separate MMR and varicella vaccines unless parents specifically prefer MMRV 1
  • The 3-year-old in question falls within this age range (36 months)

Risk of Febrile Seizures

• MMRV vaccine is associated with a higher risk of fever and febrile seizures 5-12 days after the first dose compared to separate MMR and varicella vaccines 1
• Risk estimate: Approximately one extra febrile seizure for every 2,300-2,600 MMRV vaccine doses 1
• The 47-month cutoff for this recommendation was selected because approximately 97% of febrile seizures occur in children aged ≤47 months 1

Contraindications and Precautions

Absolute Contraindications for MMRV

• History of anaphylactic reaction to neomycin
• Allergic reaction to gelatin or other vaccine components
• Immunocompromised status (blood dyscrasias, leukemia, lymphomas, immunodeficiencies)
• Family history of congenital immunodeficiencies (unless immune competence has been demonstrated)
• Systemic immunosuppressive therapy
• Pregnancy 1

Important Precaution

• A personal or family history (sibling or parent) of seizures of any etiology is a precaution for MMRV vaccination 1
• Children with personal or family history of seizures should receive separate MMR and varicella vaccines instead of MMRV 1

Vaccine Efficacy and Benefits

• Both vaccination approaches (MMRV or separate MMR+V) provide the same protection against measles, mumps, rubella, and varicella 1
• The two-dose regimen provides significantly higher protection (98.3% efficacy) compared to a single dose (94.4% efficacy) 2
• MMRV requires one fewer injection, which may be preferred by some parents and children 1

Clinical Decision Algorithm

1. Assess age: The child is 3 years old (36 months), falling within the 12-47 month range
2. Assess seizure history:
   • If personal or family history of seizures: Use separate MMR and varicella vaccines
   • If no seizure history: Proceed to next step
3. Discuss with parents:
   • Explain that MMRV results in one fewer injection
   • Explain the slightly increased risk of febrile seizures with MMRV
   • Use Vaccine Information Statements to facilitate discussion
4. Make recommendation:
   • Unless parents specifically request MMRV, recommend separate MMR and varicella vaccines
   • Document discussion and parental preference

Important Considerations

• The risk of febrile seizures is highest in younger children and decreases with age, but the precaution still applies to 3-year-olds 1
• Febrile seizures, while concerning and requiring medical attention, generally have an excellent prognosis 1
• The benefit of fewer injections with MMRV must be weighed against the small increased risk of febrile seizures 1
• For the second dose (typically at age 4-6 years), MMRV is generally preferred regardless of which vaccines were used for the first dose 1