[A live attenuated varicella vaccine].

Area of Science:

• Virology
• Immunology
• Public Health

Context:

• The Oka strain vaccine was developed from a wild-type varicella-zoster virus (VZV) isolated in 1974.
• Initial use targeted hospitalized children to prevent nosocomial varicella outbreaks due to limited alternatives.
• Extensive studies have demonstrated the vaccine's immunogenicity, tolerability, and efficacy in various populations.

Purpose:

• To describe the development, adaptation, and clinical evaluation of the Oka strain varicella vaccine.
• To analyze the epidemiological impact of different vaccination strategies, particularly universal immunization.
• To advocate for the adoption of universal varicella vaccination in Japan.

Summary:

• The Oka strain vaccine, adapted in MRC-5 cells, contains cell-free VZV and prevents varicella transmission.
• Licensed in Japan in 1987, its uptake remained low (~40% in 2008) due to non-compulsory status, failing to alter VZV circulation.
• Universal immunization in the USA since 1996 (89% coverage in 2006) led to dramatic reductions in varicella incidence, hospitalizations, and mortality.

Impact:

• Successful global administration to millions, demonstrating widespread acceptance and availability.
• Significant public health benefits observed in countries with high vaccination coverage, including reduced disease burden and healthcare expenditures.
• Highlights the critical need for universal immunization strategies to control varicella effectively.