[Varicella vaccination]

Varicella is a highly contagious disease due to varicella-zoster virus (VZV) belonging to the herpesvirus family. Following infection, the virus remains latent in neural ganglia, and upon subsequent reactivation VZV may cause zoster. While mostly a mild disorder in childhood, varicella tends to be more severe in adults. Healthy individuals may develop complications such as bacterial superinfections, pneumonia or encephalitis. Varicella may be fatal, especially in neonates and in immunocompromised persons. Control of varicella can be achieved only by widespread vaccination. The purpose of this review is to summarize the impact and the concerns of an universal varicella vaccination. The vaccines are based on the attenuated Oka-strain. The positive results of extensive safety, efficacy and cost-effectiveness analyses have warranted the introduction of these vaccines in the USA in 1995 and, more recently, in Australia and in Canada. However, European countries have some concerns. At low levels of coverage, there is a possible shift of the disease in older children and adults. At high levels of coverage, without natural exposure to the wild virus, the duration of the protection against varicella in vaccinated children could wane and zoster in elderly could increase. Recent reports suggest that a booster dose or a two doses regimen would be better for adequate immunisation in childhood. Vaccines combining measles, mumps, rubella and varicella are currently under studies and would warrant a high coverage.