25 years' experience with the Biken Oka strain varicella vaccine: a clinical overview.

Although commonly considered a benign disease in childhood, varicella is a potentially serious infection not only in high risk groups such as children with immune deficiencies, but also in otherwise healthy adults and children. Complications include bacterial superinfections, pneumonia and encephalitis, and the infection can be fatal. In addition to the substantial burden of clinical disease, varicella presents a large economic burden to society. In the absence of a satisfactory treatment for varicella infection, vaccination has an important role in preventing the disease and its sequelae. The original Oka strain live attenuated varicella vaccine was developed in 1974 at the Biken Institute in Japan. Since its development more than 25 years ago, the Biken varicella vaccine has been studied in a large number of clinical trials. The wealth of clinical experience obtained with this vaccine serves to confirm its tolerability, immunogenicity and efficacy in both healthy and high risk individuals. Vaccination has been shown to prevent clinical infection and provide effective protection against the severe complications of varicella. This historical review summarises the long clinical experience with the Biken varicella vaccine and confirms that the vaccine is very well tolerated and provides long term immunity from varicella infection.