title: The effects of school holidays on transmission of varicella zoster virus, England and Wales, 1967-2008.
abstract: BACKGROUND
  Changes in children's contact patterns between termtime and school holidays affect the transmission of several respiratory-spread infections. Transmission of varicella zoster virus (VZV), the causative agent of chickenpox, has also been linked to the school calendar in several settings, but temporal changes in the proportion of young children attending childcare centres may have influenced this relationship.
  
  
  METHODS
  We used two modelling methods (a simple difference equations model and a Time series Susceptible Infectious Recovered (TSIR) model) to estimate fortnightly values of a contact parameter (the per capita rate of effective contact between two specific individuals), using GP consultation data for chickenpox in England and Wales from 1967-2008.
  
  
  RESULTS
  The estimated contact parameters were 22-31% lower during the summer holiday than during termtime. The relationship between the contact parameter and the school calendar did not change markedly over the years analysed.
  
  
  CONCLUSIONS
  In England and Wales, reductions in contact between children during the school summer holiday lead to a reduction in the transmission of VZV. These estimates are relevant for predicting how closing schools and nurseries may affect an outbreak of an emerging respiratory-spread pathogen.
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom; Statistics, Modelling and Economics Department, Public Health England, London, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Jackson
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Punam
authors.initials: P
authors.lastname: Mangtani
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Fine
authors.affiliation: Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom; Statistics, Modelling and Economics Department, Public Health England, London, United Kingdom.
authors.forename: Emilia
authors.initials: E
authors.lastname: Vynnycky
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002644:Chickenpox / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D014645:Herpesvirus 3, Human / Q000502:physiology*; D006693:Holidays / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008954:Models, Biological; D012574:Schools / Q000706:statistics & numerical data*; D013997:Time Factors; D014852:Wales / Q000453:epidemiology