title: [Comparison of subclinical infection rates between vaccinated group with type I inactivated vaccine against hemorrhagic fever and controls].
abstract: OBJECTIVE
  To compare subclinical infection rate in the vaccinated group with type I inactivated vaccine against hemorrhagic fever with renal syndrome (HFRS) with that in the controls and to understand its enhancement.
  
  
  METHODS
  A trial field was selected in Jiande County, Zhejiang Province during July 1974 to November 1997. Paired-sera before and after vaccination were collected from 401 vaccinee and 360 controls, respectively. Serum titer of indirect immunofluorescent IgG antibody (IFAT) against HFRS was detected for each of them, and its cut-off value depended on the distribution of serum antibody titer in the second determination in the controls, which could be used to evaluate subclinical infection before vaccination.
  
  
  RESULTS
  There was no significant difference in subclinical infection between those with positive and negative IFAT before vaccination, with different cut-off values for identifying subclinical infection. In both vaccinated and control groups with negative IFA before vaccination, subclinical infection rate was 7.62% in the controls, and 2.17% and 1.63% in the vaccinated ones, with cut-off values of 1:160 and 1:320, respectively, significantly different from that in the former. Subclinical infection rate was 11.38% and 6.78% in the vaccinated ones, as cut-off values of 1:20 and 1:40, respectively, without significant difference from the controls.
  
  
  CONCLUSIONS
  No increase in subclinical infection in the vaccinated group with type I inactivated vaccine against HFRS was found.
authors.affiliation: Department of Epidemiology, Shanghai Medical University, Shanghai 200032.
authors.forename: Y
authors.initials: Y
authors.lastname: Ruan
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: S
authors.initials: S
authors.lastname: Shao
authors.forename: Z
authors.initials: Z
authors.lastname: Tong
authors.forename: S
authors.initials: S
authors.lastname: Weng
authors.forename: W
authors.initials: W
authors.lastname: Zhou
authors.forename: H
authors.initials: H
authors.lastname: Gu
authors.forename: Z
authors.initials: Z
authors.lastname: Zhu
authors.forename: Z
authors.initials: Z
authors.lastname: Xu
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002681:China / Q000453:epidemiology; D005260:Female; D018063:Hantaan virus / Q000276:immunology*; D006480:Hemorrhagic Fever with Renal Syndrome / Q000453:epidemiology / Q000517:prevention & control*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D015994:Incidence; D008297:Male; D008403:Mass Screening; D014611:Vaccination; D015164:Vaccines, Inactivated; D014765:Viral Vaccines
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D015164:Vaccines, Inactivated; D014765:Viral Vaccines