Impact on immunization of seasonal cycle of chickenpox

The objective of this work was to study the effect of incorporating a seaso nal term in a compartmental age-structured theoretical transmission model, on the performance of vaccination strategies for chickenpox. The epidemiolo gic parameters are taken from data or are based on a review of literature. We used a realistic age-structure model (RAS): It is a model that incorpora te both age and seasonal structure. The seasonality was introduced in the m odel with the addition of sinusoidal forcing term. This seasonal term varie s between 0 and 1. From a susceptible/exposed/infectious/removed (SEIR) mod el with or without age-structure, the pattern of time series is dramaticall y modified after introducing a seasonal term. This dynamic ends to the tran sition to chaos. Regarding the evaluation of vaccination strategies, the re sults of the model without seasonality may be disturbed when the seasonalit y is introduced, especially during the first 30 years of simulations.