title: Effectiveness of seasonal influenza vaccine against clinically diagnosed influenza over 2 consecutive seasons in children in Guangzhou, China: a matched case-control study.
abstract: Influenza vaccine has to be reformulated each year due to the ever-changing antigenicity of the influenza virus. However, few post-licensure studies of influenza vaccine are available in China. We aimed to measure the effectiveness of seasonal influenza vaccine during 2 consecutive seasons. Among children in Guangzhou aged 6 to 59 mo in 2010-2012, we matched each child with clinically diagnosed influenza to 3 healthy children. Cases with clinically diagnosed influenza were identified from surveillance system. Healthy controls were randomly sampled from the Children's Expanded Programmed Immunization Administrative Computerized System. Conditional logistic regression was used to calculate vaccine effectiveness (VE). A total of 275 matched sets of subjects were included. VE levels against clinically diagnosed influenza for both seasons combined was 47.4% [95% confidence interval (CI), 8.5-69.8%] for full vaccination for children aged 6-35 mo, 33.6% (95% CI, 5.4-53.5%) for any vaccination for children aged 6-59 mo, respectively. VE by time since vaccination for any vaccination was 34.6% (95% CI, 4.7-55.2%) in 0-5 mo, and no protection was observed in 6-11 mo. Annual, full and timely vaccination should be encouraged for children.
authors.affiliation: Guangzhou Center for Disease Control and Prevention; Guangzhou, Guangdong, P.R. China; School of Public Health and Tropical Medicine; Southern Medical University; Guangzhou, Guangdong, P.R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: He
authors.forename: Jianxiong
authors.initials: J
authors.lastname: Xu
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Jianyun
authors.initials: J
authors.lastname: Lu
authors.forename: Kuibiao
authors.initials: K
authors.lastname: Li
authors.forename: Zhaotian
authors.initials: Z
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Wang
authors.forename: Qiongying
authors.initials: Q
authors.lastname: Yang
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Dong
authors.forename: Xiangyi
authors.initials: X
authors.lastname: Liu
authors.forename: Xuehong
authors.initials: X
authors.lastname: Wu
authors.forename: Wensui
authors.initials: W
authors.lastname: Hu
authors.forename: Danfeng
authors.initials: D
authors.lastname: Zhang
authors.forename: Jiayun
authors.initials: J
authors.lastname: Lv
authors.forename: Jun
authors.initials: J
authors.lastname: Nie
authors.forename: Wei
authors.initials: W
authors.lastname: Zhu
authors.forename: Chuanxi
authors.initials: C
authors.lastname: Fu
mesh_terms: D016022:Case-Control Studies; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D008297:Male; D011358:Product Surveillance, Postmarketing
chemical_list: D007252:Influenza Vaccines
keywords: China; case-control studies; children; seasonal influenza; vaccine