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Varicella Vaccine Effectiveness and Duration of Protection

Information for Healthcare Providers

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
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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)

    (1)Vázquez 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.

    (2)Kuter 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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References

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