Epidemiological characteristics of varicella outbreaks in schools and child care settings in Xihu district of Hangzhou, 2009-2014

Objective To understand the epidemiological characteristics of varicella outbreaks in schools and child care settings in Xihu district of Hangzhou, and provide scientific evidence for the varicella prevention and control in schools.Methods Descriptive epidemiological analysis was conducted on the incidence data of varicella outbreaks in the schools and child care settings in Xihu district during 2009-2014.Results A total of 28 varicella outbreaks occurred in schools and child care settings during this period, and 354 cases reported with the incidence of 6.59. The incidence peaks were during March-April and during September-December. Seventeen outbreaks occurred in primary schools(60.71%). The cases were mainly distributed in age group 6-11 years(250 cases, 70.62%). A total of 179 breakthrough cases were reported from 2009 to 2014, accounting for 50.56% of the total cases. The index cases were breakthrough cases in 13 outbreaks(46.43%).Conclusion The incidence of varicella outbreak was high in schools, especially primary schools, but the protective effect of one dose varicella vaccination is insufficient, The immunization of 2 dose varicella vaccine would facilitate the varicella prevention and control in schools.