The incidence of varicella in southern Taiwan: a life table method estimation among susceptible population

Previous studies have failed to estimate the size of population at risk and underestimated the incidence of varicella among susceptible population. In this study, we calculated the incidence of varicella and its complications in Taiwan based on a life table method, in which the size of population at risk was taken into account. Population-based data were obtained from the Bureau of National Health Insurance. The age-specific incidences estimated by the uncorrected and corrected methods were compared. The incidence of varicella increased sharply after infancy and peaked at 16.7% in children aged 5 years. A correction which assumes the introduction of varicella vaccine resulted in a higher incidence of 19.5% in children aged 5 years. The lifetime cumulative incidence increased to around 76%. Sensitive surveillance of varicella and correct incidence estimate among susceptible population are essential in countries that have implemented or are about to implement varicella vaccination.