Epidemiology of Varicella-Zoster Virus in England and Wales.

Many countries are studying currently the possibility of mass vaccination against varicella. The objective of this study was to provide a complete picture of the pre-vaccine epidemiology of the Varicella-Zoster Virus in England and Wales to aid in the design of immunisation programs. Population-based data including general practitioner sentinel surveillance, hospitalisation data, and death certificates from England and Wales were analysed. The average incidence rates for varicella and zoster between 1991 and 2000 were 1,291 and 373 per 100,000 years, respectively. Overall hospitalisation rates were equal for varicella and zoster (4.5 vs. 4.4 hospitalisation per 100,000 population) with 5 and 8%, respectively, having underlying immunosuppressive conditions. The age-specific proportion of cases hospitalised and length of stay were similar between the two diseases. However, the overall burden of disease is considerably higher for zoster. The number of inpatient days and case-fatality due to zoster are roughly 4 to 6 times greater than for varicella (11 vs. 3 days and 25 vs. 4 deaths per 100,000 case). These results provide base-line estimates should mass varicella vaccination be introduced in England and Wales.