Hepatitis Research Today is a free monthly online journal that collates and summarizes the latest research about Hepatitis, including details on hepatitis a, b, c, causes, symptoms.

Estimating the impact of vaccination using age-time-dependent incidence rates of hepatitis B.

Hens N, Aerts M, Shkedy Z, Kung'u Kimani P, Kojouhorova M, van Damme P, Beutels P

Center for Statistics, Hasselt University, Diepenbeek, Belgium. niel.hens@uhasselt.be

The objective of this study was to model the age-time-dependent incidence of hepatitis B while estimating the impact of vaccination. While stochastic models/time-series have been used before to model hepatitis B cases in the absence of knowledge on the number of susceptibles, this paper proposed using a method that fits into the generalized additive model framework. Generalized additive models with penalized regression splines are used to exploit the underlying continuity of both age and time in a flexible non-parametric way. Based on a unique case notification dataset, we have shown that the implemented immunization programme in Bulgaria resulted in a significant decrease in incidence for infants in their first year of life with 82% (79-84%). Moreover, we have shown that conditional on an assumed baseline susceptibility percentage, a smooth force-of-infection profile can be obtained from which two local maxima were observed at ages 9 and 24 years.

Published 4 February 2008 in Epidemiol Infect, 136(3): 341-51.
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