title: Epidemiology of pediatric herpes zoster after varicella infection: a population-based study.
abstract: BACKGROUND
  There are limited population-based data regarding pediatric herpes zoster (HZ).
  
  
  METHODS
  Children aged <12 years with varicella infections between 2000 and 2006 were identified from a national population-based database and followed-up for a diagnosis of HZ until December 2008. Since a routine varicella vaccination program was started in 2004, vaccinated children without medically attended varicella were identified between 2004 and 2006, and followed-up for a diagnosis of HZ until December 2008.
  
  
  RESULTS
  Of 27 517 children with medically attended varicella, 428 developed HZ. The incidence of HZ was 262.1 per 100 000 person-years. Of 25 132 vaccinated children without medically attended varicella, 106 developed HZ. The incidence of HZ was 93.3 per 100 000 person-years. The mean duration from varicella to HZ was 4.12 years. Children diagnosed with varicella at aged <2 years had a higher incidence (P < .001) and shorter duration (P = .04) than those diagnosed aged ≧2 years. Children diagnosed with varicella aged ≥2 but <8 years had a significantly increased incidence of HZ after than before the vaccination program (relative risk = 1.85 at 3 years of follow-up, P = .03). Children with varicella infections had a significantly greater risk of HZ than vaccinated children without a history of varicella (relative risk = 2.31 at 4 years of follow-up, P < .001).
  
  
  CONCLUSIONS
  This study demonstrates the population-based epidemiologic characteristics of pediatric HZ among those who contracted varicella. In the early postvaricella vaccination period, an increased HZ incidence was observed among children with varicella infection aged ≥2 years.
authors.affiliation: Department of Dermatology, Taipei City Hospital, Renai Branch, Taipei, Taiwan; Center for General Education, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan;
authors.forename: Su-Ying
authors.initials: SY
authors.lastname: Wen
authors.affiliation: Institute of Clinical Research and Training, Taipei City Hospital, Taipei, Taiwan and Department of Nursing, National Taipei University of Nursing and Health Sciences, Taipei, Taiwan suyinwen@ms15.hinet.net.
authors.forename: Wen-Liang
authors.initials: WL
authors.lastname: Liu
mesh_terms: D002644:Chickenpox / Q000453:epidemiology* / Q000517:prevention & control; D019433:Chickenpox Vaccine / Q000627:therapeutic use*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006562:Herpes Zoster / Q000453:epidemiology* / Q000517:prevention & control; D014645:Herpesvirus 3, Human / Q000276:immunology*; D022283:Herpesvirus Vaccines / Q000627:therapeutic use*; D006801:Humans; D017589:Immunization Programs; D015994:Incidence; D007223:Infant; D008297:Male; D011159:Population Surveillance; D012189:Retrospective Studies; D013624:Taiwan / Q000453:epidemiology; D014611:Vaccination / Q000379:methods*
chemical_list: D019433:Chickenpox Vaccine; D022283:Herpesvirus Vaccines
keywords: children; epidemiology; herpes zoster; risk factors; varicella