What are the recommendations for Varicella (chickenpox) vaccination as per the Indian Academy of Pediatrics (IAP)?

Varicella Vaccination Recommendations as per IAP

The Indian Academy of Pediatrics (IAP) recommends a two-dose varicella vaccination schedule with the first dose at 12-15 months and the second dose at 4-6 years, with a minimum interval of 3 months between doses. While the provided evidence primarily references international guidelines (ACIP, AAP, CDC), these form the basis for IAP recommendations, as India has not yet included varicella vaccine in its Universal Immunization Program.

Primary Vaccination Schedule

First Dose Timing

• Administer the first dose at 12-15 months of age for all healthy children 1, 2
• The vaccine is approved for use starting at 12 months of age 1
• This timing aligns with other routine childhood immunizations and provides early protection 2

Second Dose Timing

• Administer the second dose at 4-6 years of age (before entering prekindergarten, kindergarten, or first grade) 3, 1, 2
• The second dose may be given earlier, provided the minimum 3-month interval is maintained 3, 1
• This timing is strategically chosen because varicella incidence and outbreaks are higher among elementary school-aged children 1

Minimum Intervals Between Doses

For Children 12 Months to 12 Years

• The recommended minimum interval is 3 months between first and second doses 3, 1, 2
• If the second dose is inadvertently given between 28 days and 3 months after the first dose, it is considered valid and does not need to be repeated 3, 1
• The absolute minimum acceptable interval is 28 days, though this is not preferred 1, 2

For Adolescents and Adults ≥13 Years

• The minimum interval is 4 weeks (28 days) between doses 3, 1, 2
• Two 0.5-mL doses should be administered subcutaneously 3, 2

Catch-Up Vaccination

Children Who Missed Initial Vaccination

• Begin the two-dose series immediately at the current visit, regardless of age 1, 2
• For a 7-year-old who has never been vaccinated, give the first dose immediately and schedule the second dose 3 months later 1
• There is no need to restart the vaccine series regardless of time elapsed 1

Children Who Received Only One Dose

• All children and adolescents who received only 1 dose previously should receive a second dose 3
• The minimum 3-month interval applies for children under 13 years 1, 2

Available Vaccine Formulations

Single-Antigen Varicella Vaccine

• Approved for use in healthy persons aged ≥12 months 3, 1
• Must be used for persons ≥13 years (MMRV is not licensed for this age group) 3, 1

Combination MMRV Vaccine

• Approved only for children aged 12 months through 12 years 3, 1
• Preferred when all components (measles, mumps, rubella, varicella) are indicated and not contraindicated 3

Rationale for Two-Dose Schedule

Improved Efficacy

• Two doses provide 98% vaccine efficacy compared to 94% for a single dose 1, 2
• Recipients of 2 doses are 3.3-fold less likely to experience breakthrough varicella 3, 1, 2
• After two doses, >99% of children achieve protective antibody levels compared to 76-85% after a single dose 3, 1, 2

Immunological Response

• Studies demonstrate a greater-than-tenfold boost in antibody titers when measured 6 weeks after the second dose 3
• The second dose provides improved protection to the 15-20% of children who do not respond adequately to the first dose 3
• Indian data confirms high seroconversion rates (93.3% post first-dose, 100% post two-doses) with the 3-month interval 4

School Entry Requirements

• All children entering school should have received two doses of varicella vaccine or have other evidence of immunity 3, 1
• The high transmission risk in school settings necessitates this requirement 1
• College students and those in postsecondary educational institutions should also receive 2 doses if lacking evidence of immunity 3

Contraindications

Absolute Contraindications

• Severe anaphylactic reaction to vaccine components (neomycin or gelatin) 1
• Pregnancy 1
• Known altered immunity: HIV with CD4 <15%, hematologic or solid tumors, congenital immunodeficiency 1
• High-dose systemic corticosteroids (≥2 mg/kg/day prednisone or ≥20 mg/day) for ≥14 days 1

Important Clarifications

• Egg allergy is NOT a contraindication (vaccine contains no egg protein) 1
• Wait at least 1 month after discontinuing corticosteroid therapy before vaccinating 1

Special Populations

HIV-Infected Children

• May receive varicella vaccine if CD4 T-lymphocyte percentage ≥15% 1
• Use 2 doses of monovalent vaccine with a 3-month interval 1

Healthcare Personnel and High-Risk Groups

• Healthcare workers must be vaccinated due to risk of VZV transmission in healthcare settings 3
• Other priority groups include household contacts of immunocompromised persons, teachers, daycare employees, and nonpregnant women of childbearing age 1

Postexposure Prophylaxis

• Administer vaccine within 3 days of exposure (>90% effective in preventing varicella) 1
• Vaccination within 5 days is approximately 70% effective in preventing varicella and 100% effective in modifying severe disease 1
• Avoid salicylates for 6 weeks after vaccination due to risk of Reye syndrome 1

Indian Context Considerations

Current Status in India

• Varicella vaccine is not included in India's Universal Immunization Program due to cost considerations and the belief that lifelong immunity occurs following primary infection 5, 6
• Despite this, the expanded spectrum of VZV disease and mounting evidence suggest the need for routine immunization 6
• Indian studies demonstrate that a two-dose schedule administered 3 months apart is safe and immunogenic in Indian children 4

Disease Burden

• In India, varicella outbreaks are reported at a younger age, making a two-dose vaccine schedule administered early highly efficacious 4
• The actual disease burden is underestimated as most infected individuals may not visit physicians 6
• Complications include bacterial infections (up to 5%), pneumonia, encephalitis (1 in 10,000 cases), and severe invasive group A streptococcal disease 5

Common Pitfalls to Avoid

• Do not delay the second dose beyond 4-6 years unless there are specific contraindications, as this leaves children vulnerable during peak transmission years
• Do not use MMRV vaccine in children ≥13 years—only single-antigen varicella vaccine is licensed for this age group 3, 1
• Do not restart the series if the interval between doses is longer than recommended—simply continue with the next dose 1
• Do not withhold vaccination from children with egg allergy—this is not a contraindication 1