[Effectiveness on post-exposure vaccination of varicella and its influencing factors in elementary schools in Beijing].

Objective: To evaluate the effectiveness of post-exposure varicella vaccination in elementary schools in Beijing and to explore its influencing factors.

Methods: From May to July 2007, varicella cases from 49 elementary schools in 4 districts in Beijing were observed prospectively. The study included 7882 children who were from the same classrooms, same floor or same bungalow areas with the varicella cases.