Varicella vaccines.

BACKGROUND: Varicella zoster virus infection (VZV) is widespread and clinically important as the cause of varicella pneumonitis and meningoencephalitis (a complication of primary infection/zoster) and post-herpetic neuralgia (a complication of zoster/secondary infection). The use of live-attenuated varicella vaccine to reduce the burden of these diseases has been established in many countries for a number of years. SOURCES OF DATA: Original papers and review articles including guidelines and recommendations by the American Academy of Paediatrics Committee on Infectious Diseases, the Advisory Committee on Immunization Practices and EuroSurveillance. AREAS OF AGREEMENT: Immunoassay of VZV IgG by enzyme immunosorbent assay is used as a surrogate marker for previous primary infection or successful immunization. Patients who have had natural primary infection do not require vaccination against varicella. Live VZV vaccines are safe and effective at protecting against disease caused by VZV. To ensure long-term protection, a two-dose immunization regime is strongly recommended, due to significant waning of protection following a single dose. Universal two-dose immunization has been shown to be cost-effective in Western temperate countries. In many countries, routine vaccination of children is recommended but, due to cost, often not provided by universal programmes. Cost-effectiveness of a universal programme will be determined by the baseline rate of severe varicella disease. AREAS OF CONTROVERSY: No international consensus exists: measurement of VZV immunity or cost-effectiveness of introducing VZV vaccination to a country. Decisive factors will include the pre-vaccination burden of VZV-associated disease.