Influence of two dose immunization schedule of varicella vaccine on epidemiological characteristics of varicella in Taizhou

ObjectiveTo understand the epidemiological characteristics of varicella in Taizhou after the implementation of two dose immunization schedule of varicella vaccine.

MethodsThe incidence data of varicella in Taizhou from 2011 to 2017 were collected, the epidemiological characteristics of varicella cases were analyzed by descriptive epidemiology.

ResultsA total of 16 895 cases of varicella were reported in Taizhou from 2011 to 2017 with an average annual reported incidence of 40.02/100 000. The highest incidence was 55.81/100 000 in 2015 and the lowest was 26.24/100 000 in 2011. The incidence of varicella increased from 2011 to 2015, and decreased during 2016–2017 after the implementation of two dose immunization schedule of varicella vaccine. The highest annual reported incidence was 103.77/100 000 in Tiantai county and the lowest was 17.46/100 000 in Yuhuan county. After the implementation of two dose immunization schedule of varicella vaccine, the vaccination rate increased, and there were no obvious changes in the sex ratio, seasonal distribution and age distribution of varicella cases. The incidence rate of increased in age group over 10 years and decreased in age group 0–9 years.

ConclusionThe rising trend of varicella incidence in Taizhou was eased and the incidence in vaccinated population decreased after the implementation of two dose immunization schedule of varicella vaccine, but the proportion of varicella cases in non-vaccinated population aged ≥10 years increased. It is necessary to continue the two dose immunization schedule of varicella vaccine.