title: Immune protection induced on day 10 following administration of the 2009 A/H1N1 pandemic influenza vaccine.
abstract: The 2009 swine-origin influenza virus (S-OIV) H1N1 pandemic has caused more than 18,000 deaths worldwide. Vaccines against the 2009 A/H1N1 influenza virus are useful for preventing infection and controlling the pandemic. The kinetics of the immune response following vaccination with the 2009 A/H1N1 influenza vaccine need further investigation.
  
  
  
  58 volunteers were vaccinated with a 2009 A/H1N1 pandemic influenza monovalent split-virus vaccine (15 µg, single-dose). The sera were collected before Day 0 (pre-vaccination) and on Days 3, 5, 10, 14, 21, 30, 45 and 60 post vaccination. Specific antibody responses induced by the vaccination were analyzed using hemagglutination inhibition (HI) assay and enzyme-linked immunosorbent assay (ELISA). After administration of the 2009 A/H1N1 influenza vaccine, specific and protective antibody response with a major subtype of IgG was sufficiently developed as early as Day 10 (seroprotection rate: 93%). This specific antibody response could maintain for at least 60 days without significant reduction. Antibody response induced by the 2009 A/H1N1 influenza vaccine could not render protection against seasonal H1N1 influenza (seroconversion rate: 3% on Day 21). However, volunteers with higher pre-existing seasonal influenza antibody levels (pre-vaccination HI titer ≥1∶40, Group 1) more easily developed a strong antibody protection effect against the 2009 A/H1N1 influenza vaccine as compared with those showing lower pre-existing seasonal influenza antibody levels (pre-vaccination HI titer <1∶40, Group 2). The titer of the specific antibody against the 2009 A/H1N1 influenza was much higher in Group 1 (geometric mean titer: 146 on Day 21) than that in Group 2 (geometric mean titer: 70 on Day 21).
  
  
  
  Recipients could gain sufficient protection as early as 10 days after vaccine administration. The protection could last at least 60 days. Individuals with a stronger pre-existing seasonal influenza antibody response may have a relatively higher potential for developing a stronger humoral immune response after vaccination with the 2009 A/H1N1 pandemic influenza vaccine.
authors.affiliation: Key Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Yizhuo
authors.initials: Y
authors.lastname: Sun
authors.forename: Chao
authors.initials: C
authors.lastname: Bian
authors.forename: Ke
authors.initials: K
authors.lastname: Xu
authors.forename: Weibin
authors.initials: W
authors.lastname: Hu
authors.forename: Tongyan
authors.initials: T
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Cui
authors.forename: Hongqiang
authors.initials: H
authors.lastname: Wu
authors.forename: Zhiyang
authors.initials: Z
authors.lastname: Ling
authors.forename: Yongyong
authors.initials: Y
authors.lastname: Ji
authors.forename: Guomei
authors.initials: G
authors.lastname: Lin
authors.forename: Lin
authors.initials: L
authors.lastname: Tian
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Bingnan
authors.initials: B
authors.lastname: Li
authors.forename: Guiyu
authors.initials: G
authors.lastname: Hu
authors.forename: Ning
authors.initials: N
authors.lastname: Yu
authors.forename: Wenqi
authors.initials: W
authors.lastname: An
authors.forename: Ruowen
authors.initials: R
authors.lastname: Pan
authors.forename: Paul
authors.initials: P
authors.lastname: Zhou
authors.forename: Qibin
authors.initials: Q
authors.lastname: Leng
authors.forename: Zhong
authors.initials: Z
authors.lastname: Huang
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Ma
authors.forename: Bing
authors.initials: B
authors.lastname: Sun
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006385:Hemagglutination Inhibition Tests / Q000379:methods; D006388:Hemagglutinins / Q000737:chemistry; D006801:Humans; D007107:Immune System; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D058873:Pandemics / Q000517:prevention & control; D012621:Seasons; D013997:Time Factors
chemical_list: D000914:Antibodies, Viral; D006388:Hemagglutinins; D007252:Influenza Vaccines