Varicella in non-immune persons: incidence, hospitalization and mortality rates.

This study was conducted to estimate the varicella morbidity and mortality rates per age group among the non-immune population in France. Morbidity and mortality data for the years 1990-9 were derived from nationwide databases and surveillance systems. An incidence/prevalence model was designed to quantify the non-immune population per age group. The incidence of varicella in the non-immune population peaks during childhood and again in the 25-35 years age group. For children aged 1-4 years, adults aged 25-34 years and those older than 65 years, the hospitalization rates are respectively 235, 1,438 and 8,154 per 100,000 cases, and the death rates are respectively 7, 104 and 5,345 per million cases. Case fatality or case hospitalization rates were not evenly distributed among adults and increased dramatically with age.