Varicella disease after introduction of varicella vaccine in the US, 1995-2000

Chickenpox is now one of the last of the infectious diseases of childhood that remain mostly uncontrolled. An effective vaccine has been available for many years but has not been used for routine immunisation in many countries. This is because the effect of giving the vaccine in early life on the subsequent development of herpes zoster is not known; high immunisation rates are important to ensure that the age distribution does not shift towards older age groups in whom the disease is more serious; and the disease is generally considered innocuous, especially in childhood when about 95% of infections occur.