What is the recommended schedule for administering the live‑attenuated varicella vaccine in children, adolescents, and adults, including timing and contraindications?

Varicella Vaccine Schedule

All children should receive two doses of varicella vaccine: the first at 12–15 months and the second at 4–6 years (before school entry), while adolescents and adults ≥13 years without immunity require two 0.5-mL doses separated by 4–8 weeks. 1

Children (12 months to 12 years)

Primary Series

• First dose: Administer at 12–15 months of age (0.5 mL subcutaneously). 2, 1
• Second dose: Administer at 4–6 years of age (before kindergarten or first grade entry). 2, 1
• The second dose may be given earlier than 4–6 years, but must be separated from the first dose by at least 3 months. 2, 1, 3
• If the second dose is inadvertently given between 28 days and 3 months after the first dose, it does not need to be repeated. 2

Vaccine Efficacy

• The two-dose regimen achieves 98.3% efficacy compared to 94.4% for a single dose, reducing breakthrough disease risk by approximately 3.3-fold. 1

Vaccine Options for Children

• Either monovalent varicella vaccine (Varivax) or MMRV (ProQuad) may be used in children 12 months through 12 years of age. 2
• Combination vaccines are preferred when all components are indicated to minimize injections. 2

Adolescents and Adults (≥13 years)

Dosing Schedule

• Two 0.5-mL doses administered subcutaneously, separated by 4–8 weeks. 1, 4, 3
• The minimum acceptable interval is 4 weeks (28 days). 1, 4, 3
• If more than 8 weeks have elapsed since the first dose, simply administer the second dose without restarting the series. 4

Vaccine Selection

• Only single-antigen varicella vaccine (Varivax) is licensed for persons ≥13 years; MMRV is not approved for this age group. 2, 1, 4

Priority Populations Requiring Vaccination

The following groups should be prioritized for timely two-dose completion: 1, 4

• Healthcare personnel
• Household contacts of immunocompromised individuals
• Teachers and daycare employees
• College students and military personnel
• Non-pregnant women of childbearing age
• International travelers
• Inmates and institutional residents

Catch-Up Vaccination

Children Who Received Only One Dose

• Administer a second dose with a minimum 3-month interval from the first dose. 2, 1
• The catch-up dose may be given at any interval longer than 3 months. 1

Adolescents and Adults Who Received Only One Dose

• Administer a second dose with a minimum 4-week interval from the first dose. 1, 4
• The catch-up dose may be given at any interval longer than 4 weeks. 1, 4

Contraindications

Absolute Contraindications

• Pregnancy: Varicella vaccine is contraindicated because wild-type varicella can cause congenital varicella syndrome. 3
  • Women should avoid conception for at least 1 month after each vaccine dose. 4
• Severe immunocompromising conditions, including: 1, 4
  • Advanced HIV with CD4 count <200 cells/µL
  • Active chemotherapy
  • High-dose corticosteroids (>2 mg/kg/day or ≥20 mg/day prednisone for ≥14 days)
• Severe allergic reaction to a previous dose or vaccine component (including neomycin). 3

Special Populations

Postpartum Vaccination

• For non-immune women, administer the first dose before hospital discharge after pregnancy completion or termination. 4
• Give the second dose 4–8 weeks later, ideally at the routine 6–8 week postpartum visit. 4

Immunocompromised Patients

• Bone marrow transplant recipients should be treated as non-immune regardless of prior vaccination history. 1

Drug Interactions and Timing Considerations

Salicylates

• Avoid salicylates for 6 weeks after vaccination due to the theoretical risk of Reye syndrome. 3

Immune Globulins and Blood Products

• Administration of immune globulins or blood products may interfere with vaccine response. 3
• After receiving VariZIG (varicella-zoster immune globulin), wait ≥5 months before administering varicella vaccine. 1

Other Live Vaccines

• Varicella vaccine may be given simultaneously with MMR or other live vaccines. 3, 5
• If not given simultaneously, wait at least 30 days between MMR and varicella vaccine to avoid decreased vaccine effectiveness. 3, 5

Tuberculin Skin Testing

• Perform tuberculin skin testing (PPD) before vaccination, on the same day, or at least 4 weeks after varicella vaccination, as live vaccines may temporarily suppress tuberculin reactivity. 3

Common Pitfalls to Avoid

• Do not use MMRV vaccine in persons ≥13 years—only single-antigen varicella vaccine is licensed for this age group. 1, 4
• Do not restart the series if the interval between doses exceeds the recommended timeframe; simply administer the second dose when the patient presents. 4
• Do not delay the second dose in children beyond 4–6 years unless medically contraindicated, as this is the optimal time for school-entry protection. 2
• Do not administer varicella vaccine to pregnant women; screen for pregnancy before each dose in women of childbearing age. 4, 3
• Do not give varicella vaccine within 5 months of VariZIG administration, as passive antibodies will interfere with vaccine response. 1