Protection against varicella-zoster virus (VZV) infection through immunisation has been available since 1995 and this live attenuated vaccine is currently licensed for use in several countries, including the United States, although it is available on a named-patient basis only in the United Kingdom. The vaccine is administered subcutaneously as a single 0.5 ml dose to healthy children aged between 12 months and 12 years. It may also be administered as two 0.5 ml doses given 4-8 weeks apart to children over the age of 13 years and to adults. Seroconversion rates of 97% have been demonstrated in infants receiving one dose of vaccine, with consistently high levels of antibody present for up to 10 years following completion of the course. In those recipients over the age of 13 years, 78% seroconverted after the first dose, rising to 99% after completion of the course.
The vaccine is recommended routinely for all children aged 12-18 months, susceptible adolescents and adults, including high-risk occupational groups, e.g. health care workers, and nonpregnant women of childbearing age following determination of their immune status to VZV. Immunisation with varicella vaccine should also be considered for susceptible travellers, as confirmed by serological testing where appropriate. This applies particularly to those travelling to tropical countries, especially when close contact with the indigenous population is likely as varicella infection occurs predominantly in adolescents and adults, with significant morbidity and mortality in endemic countries. Recent immigrants from tropical to temperate climates may also be at risk of infection from the indigenous population to which they migrate. Consequently, if the same group return to their country of origin for a visit, they may inadvertently transmit varicella infection to those that they visit.
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