When Was the Varicella Vaccine First Introduced in the United States?
The varicella (chickenpox) vaccine was licensed in the United States in March 1995, and the Advisory Committee on Immunization Practices (ACIP) issued its first recommendations for routine vaccination in July 1996. 1
Timeline of Varicella Vaccine Introduction
Initial Licensure and Recommendations
- The FDA approved Varivax (Merck & Co.) in March 1995 for use in healthy children aged ≥12 months, adolescents, and adults 1, 2
- The vaccine uses the live-attenuated Oka strain of varicella-zoster virus, which was licensed from the Biken Institute at Osaka University in Japan 2
- ACIP issued its first formal recommendations for varicella prevention in July 1996, recommending routine vaccination of children aged 12-18 months, catch-up vaccination for susceptible children aged 19 months to 12 years, and vaccination of high-risk contacts 1
Evolution of Recommendations
- In February 1999, ACIP expanded its recommendations to include child care and school entry requirements, postexposure vaccination, outbreak control measures, vaccination of certain HIV-infected children, and strengthened recommendations for high-risk adults 1
- In June 2006, ACIP recommended a routine two-dose vaccination schedule to further reduce varicella disease and outbreaks, marking a major shift from the original single-dose recommendation 1, 3
- In September 2005, the combination MMRV vaccine (ProQuad) was licensed for children aged 12 months through 12 years 1
Impact Since Introduction
Disease Reduction
- Before vaccine availability, varicella caused an estimated 4 million cases, 11,000 hospitalizations, and 100 deaths annually in the United States 1, 4
- By 2000, vaccination coverage reached 74-84% in active surveillance communities, with reported cases declining 71-84% 1
- By 2005, national vaccination coverage among children aged 19-35 months reached 88%, with varicella incidence declining 53-88% in states with adequate reporting 1
- Varicella-related hospitalizations declined 88% during 1994-2002, with substantial declines across all age groups 1
Two-Dose Era Outcomes
- Following the 2006 two-dose recommendation, varicella incidence declined an additional 76-67% by 2010 in active surveillance areas, representing a 98% overall decline since 1995 3
- Varicella outbreaks decreased dramatically, from 236 outbreaks during 1995-1998 to only 12 during 2007-2010 in Antelope Valley, California 3
- The two-dose schedule provides 98% efficacy against any varicella disease and 100% efficacy against severe disease, compared to 94% efficacy with one dose 1, 5