Summary of Rationale for Varicella Vaccination

Information for Healthcare Providers

Varicella vaccine is effective at preventing varicella and its complications

  • Studies show that 1 dose of varicella vaccine is 85% effective.
  • Studies show that 2 doses of varicella vaccine will provide additional protection to 1 dose of varicella vaccine (88 to 98% vaccine effectiveness).
  • Varicella vaccine is almost 100% effective at preventing severe cases of varicella.
  • Vaccination prevents an estimated 3.5 million cases of varicella and 9,000 hospitalizations and 100 deaths from varicella in the United States each year.

Varicella vaccine protects people who cannot get vaccinated

  • Varicella vaccine is not licensed for several groups of people at high risk for severe varicella. This includes infants less than 12 months of age, pregnant women, and people who have compromised immune systems due to disease or medications. For more information, see Contraindications and Precautions for Varicella Vaccination.
  • Vaccination of eligible children and adults, including family contacts, and healthcare professionals reduces varicella transmission and protects people who are not eligible for vaccination. Maintaining high vaccine coverage in the community protects everyone, including those at highest risk.

Evolution of use of varicella vaccine in the United States

  • 1995: Food and Drug Administration licensed varicella vaccine.
  • 1996: The Advisory Committee on Immunization Practice (ACIP) recommended
    • routine vaccination of children aged 12 to 18 months,
    • catch-up vaccination of susceptible children aged 19 months to 12 years, and
    • vaccination of susceptible people, such as healthcare professionals and family contacts, who interact closely with people at high risk for serious complications from varicell

    ACIP recommended 1 dose of varicella vaccine for children aged 12 months to 12 years, and 2 doses separated by 4 to 8 weeks for people aged 13 years and older.

  • 1999: ACIP updated the recommendations to include use of varicella vaccine
    • in people exposed to varicella and for outbreak control, and
    • in adolescents and adults at high risk for exposure or transmission of varicella.
  • 2007: ACIP adopted new recommendations for the use of live attenuated varicella vaccines which included implementation of a routine 2-dose varicella vaccination program for children and 2 doses of vaccine for all adolescents and adults without evidence of immunity to varicella. ACIP recommended that children get one dose at age 12 to 15 months and another dose at age 4 to 6 years.Two doses of varicella vaccine were recommended to:

    1) further decrease cases of varicella and its complications

    2) further decrease and prevent varicella outbreaks

    • Despite the successes of the 1-dose vaccination program in children, 1 dose was not sufficient to prevent varicella outbreaks in high transmission settings (e.g., schools, hospitals, and residential settings).
    • Outbreaks were fewer and smaller in size than in the pre-vaccine era, but they continued to occur in schools with high 1-dose coverage.

    3) improve protection against varicella

    • Studies of immune response showed that a greater proportion of people who had received 2 doses of vaccine had antibody titers ≥5 gpELISA U/mL (an approximate correlate of protection) and a >10-fold boost in geometric-mean-titer at 6 weeks after vaccination compared with people who had received 1 dose of vaccine.


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Page last reviewed: August 22, 2012