About the Vaccine

Varicella Vaccine Composition, Dosage, and Administration

Two vaccines containing varicella virus are licensed for use in the United States.

• Varivax® is the single-antigen varicella vaccine.
• ProQuad® is a combination measles, mumps, rubella, and varicella (MMRV) vaccine.

Note: ProQuad® is not currently available. For more information, see Merck’s Web site on vaccine supply.

Both vaccines contain live, attenuated varicella-zoster virus derived from the Oka strain.

Children 12 months through 12 years old

• 2 doses (0.5 ml each) of varicella vaccine should be given subcutaneously, separated by at least 3 months
• MMRV vaccine is approved for healthy children in this age group

Single-antigen vaccine and MMWR vaccine can be used for the routine 2-dose varicella vaccination.

• First dose: 12 through 15 months
• Second dose: 4 through 6 years.

For the first dose, CDC recommends that MMR and varicella vaccines be given separately in children 12 through 15 months old unless the parent or caregiver expresses a preference for MMRV vaccine.

Both vaccines may be given at the same time as other vaccines for children 12 through 15 months and 4 through 6 years old.

People 13 years or older

• 2 doses (0.5 ml each) of the single-antigen varicella vaccine subcutaneously 4 to 8 weeks apart
• MMRV vaccine is not approved for people in this age group

For package inserts, see Varivax® and ProQuad®.

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Varicella Vaccine Effectiveness and Duration of Protection

Vaccine Effectiveness

One dose

• 1 dose of single-antigen varicella vaccine is—
  • 85% effective at preventing any form of varicella
  • almost 100% effective against severe varicella

Two doses

• In a pre-licensure clinical trial, 2 doses of vaccine were—
  • 98% effective at preventing any form of varicella
  • 100% effective against severe varicella
• In post-licensure studies, 2 doses of vaccine were—
  • 88% to 98% effective at preventing all varicella

In Children with HIV-infection

• 1 dose of single-antigen varicella vaccine is—
  • 82% effective at preventing any form of varicella

Duration of Protection

It is not known how long a vaccinated person is protected against varicella. But, live vaccines in general provide long-lasting immunity.

• Several studies have shown that people vaccinated against varicella had antibodies for at least 10 to 20 years after vaccination. But, these studies were done before the vaccine was widely used and when infection with wild-type varicella was still very common.
• A case-control study conducted from 1997 to 2003 showed that 1 dose of varicella vaccine was 97% effective in the first year after vaccination and 86% effective in the second year. From the second to eighth year after vaccination, the vaccine effectiveness remained stable at 81 to 86%. Most vaccinated children who developed varicella during the 8 years after vaccination had mild disease.¹
• A clinical trial showed that children with 2 doses of varicella vaccine were protected 10 years after being vaccinated. Fewer people had breakthrough varicella after 2 doses compared with 1 dose. The risk of breakthrough varicella did not increase over time.²
  

  ¹Vázquez M, LaRussa PS, Gershon AA, Niccolai LM, Muehlenbein CE, Steinberg SP, Shapiro ED. Effectiveness over time of varicella vaccine. JAMA. 2004 Feb 18;291(7):851-5.

  ²Kuter B, Matthews H, Shinefield H, Black S, Dennehy P, Watson B, et al. Ten year follow-up of healthy children who received one or two injections of varicella vaccine. Pediatr Infect Dis J. 2004;23:132–7.

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