Can a 3‑year‑4‑month‑old child receive the varicella (chickenpox) vaccine?

Varicella Vaccine Administration at 3 Years 4 Months

Yes, a 3-year-4-month-old child can and should receive the varicella vaccine if they have not been previously vaccinated or have no documented history of chickenpox. This age falls well within the approved and recommended vaccination window.

Age Eligibility and Approval

• The varicella vaccine (Varivax) is FDA-approved for administration starting at 12 months of age, making a 3-year-4-month-old child fully eligible 1
• The American Academy of Pediatrics recommends routine varicella vaccination for all healthy children beginning at 12-15 months of age 2, 3

Recommended Vaccination Schedule for This Age Group

For a 3-year-4-month-old child who has never been vaccinated:

• First dose: Administer immediately at the current visit 2
• Second dose: Schedule 3 months later as the recommended interval 2
• The minimum acceptable interval between doses is 3 months for children 12 months through 12 years of age 2, 1
• 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 Formulation Options

• Monovalent varicella vaccine (Varivax): Approved for all ages ≥12 months, administered as 0.5 mL subcutaneously 2, 1
• Combination MMRV vaccine (ProQuad): Also approved for this age (12 months through 12 years), but for children aged 12-47 months receiving their first dose, the CDC recommends using separate MMR and varicella vaccines rather than ProQuad due to increased febrile seizure risk (approximately one additional febrile seizure per 2,300-2,600 doses) 2
• Since this child is 3 years 4 months (40 months), they fall within the 12-47 month window where separate vaccines are preferred for the first dose 2

Critical Importance of Two-Dose Series

• Two doses provide 98% efficacy against any varicella disease and 100% efficacy against severe disease, compared to only 94% efficacy with one dose 2, 3, 4
• Recipients of two doses are 3.3-fold less likely to develop breakthrough varicella compared to one-dose recipients 2, 4
• After two doses, >99% of children achieve protective antibody levels, compared to only 76-85% after a single dose 2
• Single-dose vaccination has proven insufficient to prevent outbreaks even in highly vaccinated populations 5

Contraindications to Screen For

Before administering the vaccine, ensure the child does NOT have:

• History of severe anaphylactic reaction to neomycin or gelatin 2, 3
• Known severe immunodeficiency (HIV with CD4 <15%, hematologic or solid tumors, congenital immunodeficiency) 2
• Current high-dose systemic corticosteroids (≥2 mg/kg/day prednisone or ≥20 mg/day for ≥14 days) - if recently discontinued, wait at least 1 month before vaccinating 2
• Documented history of chickenpox verified by a healthcare provider (natural infection provides lifelong immunity and vaccination is unnecessary) 3, 6

Important clarifications:

• Egg allergy is NOT a contraindication (the vaccine contains no egg protein) 2
• Contact dermatitis to neomycin is NOT a contraindication 2
• Inhaled, nasal, or topical steroids do NOT contraindicate vaccination 2

Administration Details

• Each dose is 0.5 mL administered subcutaneously or intramuscularly 1
• The vaccine must be reconstituted immediately before use and administered within 30 minutes 1
• Do not freeze reconstituted vaccine 1

Common Pitfall to Avoid

Do not delay vaccination thinking the child is "too young" or needs to wait until 4-6 years of age. While the second dose is routinely recommended at 4-6 years before school entry, the first dose should be given as soon as possible starting at 12 months 2. This 3-year-4-month-old child is already overdue for their first dose if they have never been vaccinated.