Chickenpox Vaccine Overview
The chickenpox vaccine is called varicella vaccine, with the primary brand name being Varivax (monovalent varicella vaccine) and ProQuad (combination measles-mumps-rubella-varicella or MMRV vaccine). 1
Available Vaccine Formulations
Varivax is a monovalent (single-antigen) varicella vaccine manufactured by Merck & Co, approved for use in individuals 12 months of age and older, including adolescents and adults 1
ProQuad is a combination quadrivalent vaccine (MMRV) also manufactured by Merck & Co, approved only for children aged 12 months through 12 years 1
Both vaccines are live-attenuated vaccines derived from the Oka strain of varicella-zoster virus 2
Vaccine Composition and Administration
The vaccine is a lyophilized (freeze-dried) preparation containing live-attenuated varicella-zoster virus 1
It is administered subcutaneously in 0.5-mL doses 1
The vaccine uses the Oka strain originally licensed from the Biken Institute at Osaka University in Japan 2
Clinical Context
Varicella vaccine was first licensed in the United States in 1995 1
The Centers for Disease Control and Prevention (CDC) notes that before vaccine availability, varicella caused approximately 4 million cases, 11,000 hospitalizations, and 100 deaths annually in the United States 1
The vaccine prevents chickenpox, a highly contagious disease caused by varicella-zoster virus that typically presents with fever, malaise, and a generalized vesicular rash of 250-500 lesions 3
Recommended Dosing Schedule
Children 12 months through 12 years: Two 0.5-mL doses separated by at least 3 months, with the first dose routinely given at 12-15 months and the second dose at 4-6 years 1, 4
Persons 13 years and older: Two 0.5-mL doses separated by at least 28 days 1, 4
If the second dose is inadvertently given between 28 days and 3 months after the first dose in children, it does not need to be repeated 1, 4
Vaccine Effectiveness
Two-dose vaccination provides 98% efficacy for prevention of any varicella disease and 100% efficacy for prevention of severe disease, compared to 94% efficacy with a single dose 1
Recipients of two doses are 3.3-fold less likely to experience breakthrough varicella compared to those receiving only one dose 1
Long-term studies demonstrate 90% vaccine effectiveness with no waning over a 14-year follow-up period 5