Universal varicella vaccine immunization in Japan

Area of Science:

• Virology and Immunology
• Vaccine Development and Public Health

Background:

• The Oka strain live attenuated varicella vaccine, developed in Japan in 1974, saw limited voluntary use until universal immunization began in 2014.
• Prior to universal immunization, Japan's varicella vaccine coverage was approximately 40% due to voluntary administration.

Observation:

• The United States demonstrated the efficacy of the Oka strain vaccine following its universal adoption in 1996.
• Data on the co-administration of the varicella vaccine with measles, mumps, and rubella (MMR) vaccine was lacking in Japan.
• Determining the optimal interval between the first and second vaccine doses was crucial for effective universal immunization.

Findings:

• Efficacy and safety data for co-administering the varicella vaccine with the measles and rubella (MR) vaccine in Japan were required.
• Distinguishing between wild-type and Oka vaccine strains in herpes zoster patients with a history of varicella vaccination is important.

Implications:

• Universal immunization in Japan requires robust data on vaccine efficacy, safety, and appropriate administration schedules.
• Monitoring varicella and herpes zoster epidemiology is essential following the shift to universal varicella vaccination.
• Accurate strain differentiation is key for managing herpes zoster cases in vaccinated populations.