Epidemiological Characteristics of Varicella in Yunyang County, Chongqing from 2013 to 2017

Objective: To study the epidemic situation of varicella in Yunyang County from 2013 to 2017, and to provide the scientific basis for establishing measures of prevention and control. Method: The data of varicella cases were from China Information System for Diseases Prevention and Control, and varicella outbreaks were from National Management Information System for Public Health Emergency. Statistical analysis was performed with the use of Excel 2003 and descriptive epidemiological analysis was performed. Result: 2854 cases of varicella were reported in Yunyang County from 2013 to 2017, with average annual incidence of 61.67/100,000 and annual incidence of 36.45/100,000 to 92.05/100,000, in which the highest rate was in 2015 and the lowest in 2014; varicella occurred in all 4 sub district and 38 villages and towns; cases occurred all year round but with more in spring and winter; most of the sufferers were between 5 and 14 years old and students, kindergarten children and scattered children were susceptible population of varicella, in which 2660 cases were reported in total, accounting for 93.20% of the total; male to female ratio was 1.2:1 and 2404 case were reported in population under 15 years old, accounting for 84.23% ( 2404/2854); 26 cases occurred in clusters, mainly of middle and primary schools and kindergartens. There are few genotyping studies on VZV clinical isolates and no reports on new clade typing in China and susceptible population aged 1 and above recommended to get varicella vaccine in vaccination schedule. Conclusion: Most varicella outbreaks in Yunyang County occurred during winter and spring and students, kindergarten children and scattered children were high risk population of varicella. We should improve the living and learning environment of schools, knowledge so coverage rate of the first injection of varicella vaccine and maintain high coverage rate in children, as well as actively discuss about the second injection, in order to effectively control varicella situation and protect public health.