title: [Immunogenicity and safety of a booster dose of inactivated polio vaccine].
abstract: OBJECTIVE
  To evaluate the immunogenicity and safety of a boost dose of inactivated polio vaccine (IPV) among children aged 18 months who had been administered with primary doses of IPV.
  
  
  METHODS
  Form 2011 to 2012, a total of 97 children were enrolled in the present study who were vaccinated with IPV at 2, 3, 4 months of age and boosted with the same vaccine at 18 months of age. Anti-poliovirus neutralizing antibody titers in serum were measured before and after booster vaccination, geometric mean titers (GMT) and seroprotection rate were calculated. Adverse events occurring within 30 days after booster vaccination were observed, including pain, redness/swelling and induration at the injection site, fever, vomit, abnormal crying, drowsiness, loss of appetite, irritability, and all other physical discomfort and related medications were also recorded. A descriptive analysis was performed for the safety assessment.
  
  
  RESULTS
  Immunogenicity was assessed in 84 subjects. The pre-booster seropositivity rates of neutralizing antibody against poliovirus type 1, 2, 3 before booster were all 100% (84/84) and the corresponding GMT (95% CI) was 1: 148.5 (116.49-189.29) , 1: 237.68 (178.39-316.67) and 1: 231.87 (181.27-296.58) , respectively. The seropositivity rates of neutralizing antibody against the three types of poliovirus after booster were all 100% (84/84) and the corresponding GMT (95% CI) was 1: 1612.14 (1470.57-1767.34) , 1: 1854.92 (1715.83-2005.29) and 1: 1625.50 (1452.12-1819.58) , respectively. The pre-booster titer of neutralizing antibody against poliovirus type 1, 2, 3 mainly ranged 1: 128-1: 512, which accounted for 65% (55/84) , 55% (46/84) , 74% (62/84) in each type. After the booster immunization, titers of neutralizing antibody against type 1, 2, 3 were increased as subjects with titer ≥ 1: 1024 accounted for 94% (78/84) , 95% (80/84) , 92% (77/84) , respectively.Safety was evaluated in 96 subjects, of which 16 subjects reported adverse events with the rate of 17%. The observed local events were mainly tenderness 3% (3/96) , redness/swelling and induration were not reported. The systemic adverse events included loss of appetite (8%, 8/96) , irritability (8%, 8/96) , fever (7%, 7/96) , abnormal crying (6%, 6/96) , drowsiness (6%, 6/96) and vomit (1%, 1/96) . All reported adverse events were mild or moderate. All of the local events occurred in the day of vaccination and lasted for 1-2 days, while systemic events almost developed within 2 days after vaccination and last less than 3 days.
  
  
  CONCLUSIONS
  IPV booster dose has good immunogenicity and safety profile, which provides effective protection against poliovirus.
authors.affiliation: Department of Immunization,Beijing Centre for Disease Control and Prevention,Beijing 100013, China.
authors.forename: Xiao-mei
authors.initials: XM
authors.lastname: Li
authors.forename: Zhu-jia-zi
authors.initials: ZJ
authors.lastname: Zhang
authors.forename: Hai-hong
authors.initials: HH
authors.lastname: Wang
authors.forename: Fang
authors.initials: F
authors.lastname: Liu
authors.forename: Li-wen
authors.initials: LW
authors.lastname: Zhang
authors.forename: Ping
authors.initials: P
authors.lastname: Chu
authors.forename: Ying
authors.initials: Y
authors.lastname: Xu
authors.forename: He-run
authors.initials: HR
authors.lastname: Zhang
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Dong-lei
authors.initials: DL
authors.lastname: Liu
authors.affiliation: Email: lulibj@sina.com.
authors.forename: Li
authors.initials: L
authors.lastname: Lu
mesh_terms: D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002681:China; D005260:Female; D006801:Humans; D007117:Immunization, Secondary / Q000009:adverse effects; D007223:Infant; D008297:Male; D011051:Poliomyelitis / Q000517:prevention & control*; D011054:Poliovirus Vaccine, Inactivated / Q000009:adverse effects / Q000276:immunology* / Q000627:therapeutic use*
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D011054:Poliovirus Vaccine, Inactivated