Epidemiological characteristics of varicella epidemic situation at schools and kindergartens in JinShan District of Shanghai during 2015－2022 and antibody level analysis of varicella zoster virus in healthy population / 公共卫生与预防医学

ABSTRACT

Objective To analyze the epidemiological characteristics of varicella epidemic in kindergartens and schools in Jinshan District of Shanghai from 2015 to 2022，and to understand the varicella antibody level in students aged under 30 years old，to provide evidence for developing control and prevention strategies． Methods Data of varicella epidemic situation at schools and kindergartens and varicella cases were analyzed by descriptive methods．Collect serum from healthy individuals under 30 years old to detect IgG antibody levels of varicella zoster virus.Results From 2015 to 2022, a total of 91 cases of chickenpox were reported in kindergartens and schools in Jinshan District, Shanghai, involving 412 cases.The peak incidence occurs from October to December，kindergarten childcare and primary school children were at high risk of varicella .The incidence of fever(χ2=12.93，P＜0.001) and moderate to severe rash(χ2=28.79，P＜0.001) in patients with varicella vaccination was lower than that in patients without varicella vaccination. A total of 227 people were surveyed，the positive rate of varicella antibody was 62. 56%，the geometric mean titer ( GMT) was 2.22±0.68（165.96mIU/ml）．The difference of GMT(F=6.87，P＜0.001) and positive rate (χ2=29.14，P＜0.001)of antibody in different age groups was statistically significant，the positive rate was lowest in the age group of 1-3 years, and gradually increased with the increase of age. Conclusion Autumn and winter in Jinshan District are the seasons with high incidence of chickenpox in kindergartens and primary schools，two doses of chickenpox inoculation can not only reduce clinical symptoms, but also block the transmission of chickenpox epidemic，it is suggested schools and health facilities make chicken pox monitoring work, get the chickenpox vaccine on time.