[Immunization of adults against varicella and herpes zoster]

Following the commercialisation in France of the varicella vaccine and the European marketing authorization for a vaccine against zoster, this article intends to review the epidemiology of varicella and herpes zoster, to expose the characteristics of the available vaccines, and to consider the advantages and caveats of the different immunisation strategies.

In France, from 550.000 to 750.000 cases of varicella are reported each year, which result in more than 3.500 hospitalizations and about 20 deaths. Subjects>or=15 years old represent 8.3% of the total number of cases of varicella, 26% of varicella-related hospitalisations and 69% of all varicella-related deaths. The susceptibility rate for the 15 years old is 10,3 and 79% of these non-immune subjects are expected to contract varicella. The vaccines currently marketed against varicella are safe, have a good immunogenicity and remain effective over the evaluated periods. Two vaccination strategies are considered: a generalized vaccination of the infants and children, or a vaccination targeted against high-risk populations and non-immune teenagers and adults. The incidence of herpes zoster is estimated in France at 235.000 new cases per year, from which 1% is hospitalized. A live attenuated vaccine using the same strain as the varicella vaccine, but at a much higher dose, proved its efficacy in terms of reducing shingles and postherpetic neuralgia incidences, of 51 and 67% respectively. This vaccine received a marketing authorisation in France, for adults>or=60 years old.

Uncertainties about the impact of vaccination on varicella and herpes zoster epidemiology have yet to be solved, such as the potential increase in herpes zoster incidence or in the absolute number of diagnosed varicella cases in older age groups, or the loss of vaccination-induced immunity with time. These questions demonstrate the need for an operational real-time surveillance network to monitor varicella and herpes zoster incidence in the setting of general population immunisation.