title: Population-based incidence of herpes zoster after introduction of a publicly funded varicella vaccination program.
abstract: BACKGROUND
  Past varicella infection (chicken pox) may reactivate into herpes zoster (shingles). Varicella vaccination leads to a reduction in cases of varicella that may in turn increase herpes zoster rates due to reduction in the immune boosting effect of exposure to varicella zoster virus against varicella reactivation. We assessed the impact of childhood varicella vaccination in Ontario, Canada on zoster incidence and healthcare visits, and established baseline zoster rates prior to zoster vaccine introduction.
  
  
  METHODS
  We used population-based, administrative databases to identify zoster incidence and healthcare use from April 1992 to March 2010.
  
  
  RESULTS
  After routine varicella vaccination, zoster incidence rates decreased 29% for children aged 0-9 and changed minimally for other ages. Age-standardized rates of hospitalizations during the study period declined by 53%, while outpatient rates declined by 9%. The annual zoster incidence for those 60 or older was 740 per 100,000.
  
  
  CONCLUSIONS
  In the early post-varicella vaccination period, incidence rates of medically attended herpes zoster did not increase for the overall population and decreased moderately for children 9 years and younger, the age group targeted for varicella vaccination.
authors.affiliation: Institute for Clinical Evaluative Sciences, Toronto, ON, Canada. peter.tanuseputro@utoronto.ca
authors.forename: Peter
authors.initials: P
authors.lastname: Tanuseputro
authors.forename: Brandon
authors.initials: B
authors.lastname: Zagorski
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Chan
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Kwong
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019433:Chickenpox Vaccine / Q000008:administration & dosage* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D006562:Herpes Zoster / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D014611:Vaccination / Q000379:methods*; D055815:Young Adult
chemical_list: D019433:Chickenpox Vaccine