Study on epidemic factors of varicella outbreak under high varicella vaccine coverage
10.16462/j.cnki.zhjbkz.2019.04.010
- Author:
Lei ZHANG
1
;
Yong WANG
;
Yuan-bao LIU
;
Xiang SUN
;
Fen-yang TANG
;
Ming-hao ZHOU
Author Information
1. School of Public Health, Nanjing Medical University, Nanjing 211166, China
- Publication Type:Research Article
- Keywords:
Varicella vaccine;
Vaccine effectiveness;
Breakthough cases
- From:
Chinese Journal of Disease Control & Prevention
2019;23(4):417-420,463
- CountryChina
- Language:Chinese
-
Abstract:
Objective To explore the epidemic factors of varicella transmission under high varicella vacince coverage, assess the vaccine effectineness of one dose of varicella vaccine, so as to provide scientific basis for controlling the varicella outbreak and optimizing the varicella immunization strategy. Methods A 1 ∶〗2 paired case-control study of a varicella outbreak was conducted in a primary school in central region of Jiangsu Province in 2018. Analysis of varicella epidemic factors was performed using conditional logistic stepwise regression. Results This outbreak lasted for 14 days. A total of 45 students were infected with varicella, of which 71.1% were breakthrough cases. The fever, rash degree and disease course of breakthrough cases were all relatively mild compared with those without immune history (all P<0.05).The results of conditional logistic stepwise regression suggested that participating in extracurricular tutoring institutions(OR=2.6, 95% CI:2.0-3.2), having brothers or sisters(OR=2.5, 95% CI:2.1-4.3), without vaccination history of varicella vaccine(OR=2.7, 95% CI:2.4-4.2), and contacting with varicella patients (OR=2.4, 95% CI:1.1-5.3) were risks factor for varicella transmission. Time since vaccination >5 years and the initial immunization age <15 months were potential risk factors for breakthrough cases. The overall vaccine effectiveness of one dose of varicella vaccine was 77.9%(95% CI: 53.3%-92.1%). The fever, severity of the rash and the course of the disease were all milder than those without the history of immunization (all P<0.05). Conclusions The clinical symptoms of the breakthrough cases are relatively mild, and one dose of varicella vaccine is insufficient to control the outbreak of varicella with limited vaccine effectiveness. Two doses of varicella immunization strategy is recommended.
