Statistical modeling for correlate of protection using accelerated failure time models and piecewise methods.

Abstract

Chicken pox is an important childhood illness affecting mostly school-going children. The disease can be spread through contacts between infected and susceptible individuals. It is a very contagious disease caused by the varicella-zoster virus. Its main symptoms are: blister-like rash, tiredness, itching, and fever. Chicken pox can be serious, especially in adults, babies, and people with weakened immune systems. The objective of this study was to apply parametric survival models to determine whether there is a relationship between the risk of developing a varicella case and the titer obtained after vaccination and also to apply accelerated failure time models and the piecewise exponential model to determine the threshold that corresponds to the titer which best reflects the change in the risk of breakthrough varicella disease. In this analysis we applied the accelerated failure time models (Weibull model, the Log-logistic, the lognormal model) and the piecewise exponential model. The