Characteristics of breakthrough varicella cases with different doses of varicella vaccine immunization history in Tongzhou District of Beijing during 2013 to 2017

Abstract

Objective To analyze the epidemiological characteristics of breakthrough varicella cases with different doses of varicella vaccine immunization history in Beijing Tongzhou from 2013 to 2017. Methods Data about varicella incidence and immunization history were obtained through spot investigation and consulting the information systems of Chinese Disease Control and Prevention and Beijing′s Immunization Programme. Descriptive epidemiological method was used for statistical analysis. Results From 2013 to 2017, Tongzhou District reported 2 102 cases of varicella in primary and middle schools and kindergartens, which included 989 cases of primary varicella, 966 breakthrough varicella cases with one-dose vaccine immunization history, and 147 breakthrough varicella cases with two-dose vaccine immunization history. There were significant differences in gender, age, and occupation among the three groups. Among the primary cases, the incidence of fever and moderate and severe rash was 46.71% and 34.68%; among the breakthrough cases with one-dose immunization history, the incidence of fever and moderate and severe rash was 41.20% and 17.39%; among the breakthrough cases with two-dose immunization history, the incidence of fever and moderate and severe rash was 26.53% and 7.48%. There were significant differences in the incidence of fever and rash among the three groups. The median number of varicella morbidity interval was 5.11 years in one-dose immunization history group and 2.44 years in two-dose immunization history group, and the difference between them was statistically significant. Conclusions The symptoms of fever and rash in breakthrough varicella cases become less atypical as the dose of vaccination increases. Because the clinical symptoms are relatively mild, breakthrough cases as a source of infection in collective units are more likely to be neglected. Key words: Varicella; Breakthrough case; Characteristics