title: Seroepidemiology of pertussis among elementary school children in northern Taiwan.
abstract: OBJECTIVE
  Pertussis has been considered a vaccine-preventable "childhood disease", but a shift in age distribution has been reported worldwide. We conducted a seroepidemiological study in 2013 in Taiwan to elucidate the seroprevalence of pertussis among elementary school children.
  
  
  METHODS
  With a multilevel randomized method, which included 14 variables (4 population variables, 4 socio-educational variables, and 6 medical facilities' variables), the 29 executive districts of New Taipei City, Taiwan, were categorized into five strata. From each stratum, the number of school children as well as the number of elementary schools were proportionally selected. Enzyme immunoassay was applied for pertussis immunoglobulin-G measurement.
  
  
  RESULTS
  A total of 936 children from 14 schools were recruited. Most participants (98.89%) received at least three doses of acellular diphtheria-tetanus-pertussis vaccine. The overall seropositive rate for pertussis was 33.97%. The seropositive rate was highest for students in Grade 1 (49.36%) and then declined with time, except for Grade 6 students. Students from Grade 1 to Grade 4 had a significant higher seropositive rate (37.18% vs. 27.56%, p = 0.002) than those from Grade 5 to Grade 6, but a lower geometric mean titer (18.71 NovaTec Unit/mL vs. 20.04 NovaTec Unit/mL, p = 0.20). For the class grades, geometric mean titers were positively correlated with seroprevalence (p < 0.005).
  
  
  CONCLUSIONS
  Currently, almost one-third of elementary school children in Taiwan were seropositive for pertussis, a rate lower than expected. Seroprevalence declined with increasing class grades except for Grade 6. The current national immunization program may not provide adequate protection for children against pertussis.
authors: Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors: Ching-Chia
authors: CC
authors: Kuo
authors: Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan. Electronic address: ychuang@cgmh.org.tw.
authors: Yhu-Chering
authors: YC
authors: Huang
authors: Department of Pediatrics, Chang Gung Children's Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors: Yu-Chia
authors: YC
authors: Hsieh
authors: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors: Ya-Ling
authors: YL
authors: Huang
authors: Department of Laboratory Medicine, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan.
authors: Yu-Chiau
authors: YC
authors: Huang
authors: Department of Political Science, National Taiwan University, Taipei, Taiwan.
authors: Yung-Tai
authors: YT
authors: Hung
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007124:Immunoenzyme Techniques; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D012574:Schools; D016036:Seroepidemiologic Studies; D013334:Students; D013624:Taiwan / Q000453:epidemiology; D014917:Whooping Cough / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D007074:Immunoglobulin G
keywords: Taiwan; children; pertussis; seroepidemiology