Varicella Vaccine Dosing Schedule
All healthy children should receive two doses of varicella vaccine: the first dose at 12-15 months of age and the second dose at 4-6 years of age, with a minimum interval of 3 months between doses for children aged 1-12 years, while adolescents and adults ≥13 years require two doses separated by at least 4 weeks. 1, 2
Children (12 months through 12 years)
Primary Schedule
- First dose: Administer at 12-15 months of age 1, 2
- Second dose: Administer at 4-6 years of age (before entering prekindergarten, kindergarten, or first grade) 1, 2
- Minimum interval: 3 months between doses 1, 2
- Acceptable alternative: If the second dose is inadvertently given 28 days to 3 months after the first dose, it does not need to be repeated 2
Catch-Up Vaccination
- Children who have not received their second dose should complete the schedule by age 11-12 years 1
- For previously unvaccinated children, begin the two-dose series immediately with the same 3-month minimum interval 2
Vaccine Formulation Options
- Monovalent varicella vaccine (Varivax): Approved for all ages ≥12 months, 0.5 mL subcutaneously 1, 2, 3
- Combination MMRV vaccine (ProQuad): Approved only for ages 12 months through 12 years 1, 2
- Important safety consideration: For the first dose in children aged 12-47 months, separate MMR and varicella vaccines are preferred over MMRV due to approximately one additional febrile seizure per 2,300-2,600 doses with MMRV 2
Adolescents and Adults (≥13 years)
Dosing Schedule
- Two doses required: 0.5 mL subcutaneously per dose 1, 2
- Minimum interval: 4 weeks (28 days) between doses 1, 2
- Recommended interval: 4-8 weeks between doses 1, 2
- Vaccine formulation: Must use single-antigen varicella vaccine (Varivax); MMRV is not licensed for this age group 1, 2
Priority Groups for Vaccination
Adults without evidence of immunity who should receive special consideration for vaccination include: 1
- Healthcare personnel
- Household contacts of immunocompromised persons
- Teachers and child-care employees
- College students and military personnel
- Nonpregnant women of childbearing age
- International travelers
- Residents and staff of institutional settings (including correctional institutions)
Immunocompromised Patients
General Contraindications
- Highly immunocompromised patients should NOT receive varicella vaccine, including those with: 1
- HIV infection with severe immunosuppression (CD4 <15% or CD4 count <200 cells/mm³)
- Hematologic and solid tumors
- Congenital immunodeficiency with defective T-cell-mediated immunity
- Long-term immunosuppressive therapy
Corticosteroid Considerations
- Contraindicated in patients receiving high-dose systemic corticosteroids (≥2 mg/kg/day prednisone or ≥20 mg/day) for ≥14 days 1, 2
- Wait at least 1 month after discontinuing corticosteroid therapy before vaccinating 1, 2
- Acceptable for patients on inhaled, nasal, and topical steroids 1
Special Populations Who MAY Receive Vaccine
HIV-infected children: May receive vaccine if asymptomatic with CD4 T-lymphocyte percentage ≥15% (children aged 9 months-5 years) or CD4 count ≥200 cells/mm³ (adults) 1, 2
Patients with primary complement deficiency or chronic granulomatous disease (without T-cell defects) may receive vaccine with a 2-dose schedule separated by 3 months 1
Pre-Immunosuppression Vaccination
- Ideally vaccinate ≥4 weeks before initiating immunosuppressive therapy 1
- Use 2-dose schedule: separated by ≥28 days for those aged ≥13 years and by ≥3 months for children aged 1-12 years 1
- Immune response is nearly optimal in 2-3 weeks, and replicating virus should be cleared after 3 weeks 1
Evidence of Immunity (No Vaccination Needed)
Adults are considered immune and do NOT require vaccination if they have any of the following: 1, 2
- Documentation of 2 doses of varicella vaccine at least 4 weeks apart
- U.S.-born before 1980 (except healthcare personnel and pregnant women)
- Healthcare provider-verified history of varicella or herpes zoster
- Laboratory evidence of immunity or laboratory-confirmed disease
Absolute Contraindications
- Pregnancy: Contraindicated; women should receive first dose upon completion or termination of pregnancy and second dose 4-8 weeks later 1, 2, 3
- Severe anaphylactic reaction to vaccine components (neomycin or gelatin) 1, 2, 3
- Active untreated tuberculosis 1
- Highly immunocompromised states as detailed above 1, 2
Important Clarifications on Non-Contraindications
- Egg allergy is NOT a contraindication (vaccine contains no egg protein) 1, 2
- Contact dermatitis to neomycin is NOT a contraindication 2
- Having a pregnant household member is NOT a contraindication for vaccinating other family members 2
Clinical Efficacy of Two-Dose Schedule
The two-dose regimen provides superior protection compared to single-dose vaccination: 2
- 98% efficacy against any varicella disease (vs. 94% with one dose)
- 100% efficacy against severe disease
- Recipients of 2 doses are 3.3-fold less likely to experience breakthrough varicella
- >99% of children achieve protective antibody levels after two doses (vs. 76-85% after one dose)
Special Precautions
- Avoid salicylates for 6 weeks after vaccination due to risk of Reye syndrome 3
- Tuberculin skin testing should be performed before vaccination, on the same day, or at least 4 weeks following vaccination 3
- Immune globulins and blood products may interfere with vaccine response; follow ACIP recommendations for appropriate intervals 3
- Isolate vaccinees who develop a post-vaccination rash until all lesions have crusted 2
Postexposure Prophylaxis
- Unvaccinated persons exposed to varicella should receive vaccine within 3 days of exposure (>90% effective in preventing disease) 2
- Vaccination within 5 days is approximately 70% effective in preventing varicella and 100% effective in modifying severe disease 2
- Varicella-zoster immune globulin (VariZIG) is indicated for susceptible high-risk individuals (immunocompromised, pregnant women without immunity, certain neonates) within 10 days of exposure 1, 2