title: Immunogenicity of a monovalent 2009 influenza A (H1N1) vaccine in infants: randomized, observer-masked, single-center clinical study.
abstract: The aim of this study is to further investigate the immune response of the inactivated split-virion vaccine for infants. We tested the immunogenicity and safety of the inactivated split-virion vaccine in infants, aged 6-35 months, for a randomized, observer-masked, age-stratified clinical study. We randomly divided subjects into three groups: 7.5 μg, 15 μg of hemagglutinin antigen dosage groups and seasonal influenza vaccine for children dosage group in a 2 dose regimen. A serologic analysis was performed at baseline and on day 21 and 42. 312 infants received a single dose injection of vaccine and 265 (84.94%) infants received two doses injection of vaccine. Adverse reactions were mostly mild or moderate. Among the subjects who received 7.5 μg and 15 μg of vaccine for a single dose injection, the rate of hemagglutinin inhibition titer of 1:40 or greater were 52.48% (95% confidence interval (CI) 42.83 ~ 61.95) and 61.11% (95% CI 50.78 ~ 70.53), respectively. Among the subjects receiving 7.5 μg and 15 μg of vaccine for two doses injection, the rate of hemagglutinin inhibition (HI) titer of 1:40 or greater were 90.10% (95% CI 82.73 ~ 94.53) and 94.44% (95% CI 87.64 ~ 97.60), respectively. These data suggests that 15 μg or 7.5 μg dose of hemagglutinin antigen of the inactivated split-virion vaccine was safe and two doses of injection could induce a sufficient protective immune response in infants.
  
  
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  BACKGROUND
  NCT01494740.
authors.affiliation: Shanghai Institute of Biological Products, Shanghai, 200052 China.
authors.forename: Shilei
authors.initials: S
authors.lastname: Wang
authors.affiliation: Shanghai Institute of Biological Products, Shanghai, 200052 China.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Dong
authors.affiliation: Shanghai Institute of Biological Products, Shanghai, 200052 China.
authors.forename: Wenqing
authors.initials: W
authors.lastname: Chai
authors.affiliation: Hunan Provincial Center for Disease Prevention and Control, Changsha, Hunan, China.
authors.forename: Fangjun
authors.initials: F
authors.lastname: Li
authors.affiliation: Shanghai Institute of Biological Products, Shanghai, 200052 China.
authors.forename: Shuqiao
authors.initials: S
authors.lastname: Wang
authors.affiliation: Institute Pasteur of Shanghai, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Sun
authors.affiliation: Shanghai Institute of Biological Products, Shanghai, 200052 China.
authors.forename: Ze
authors.initials: Z
authors.lastname: Chen
keywords: Immunogenicity; Infant; Influenza; Vaccine
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