title: Reconstructing the 2003/2004 H3N2 influenza epidemic in Switzerland with a spatially explicit, individual-based model.
abstract: world has not faced a severe pandemic for decades, except the rather mild H1N1 one in 2009, pandemic influenza models are inherently hypothetical and validation is, thus, difficult. We aim at reconstructing a recent seasonal influenza epidemic that occurred in Switzerland and deem this to be a promising validation strategy for models of influenza spread.
  
  
  METHODS
  We present a spatially explicit, individual-based simulation model of influenza spread. The simulation model bases upon (i) simulated human travel data, (ii) data on human contact patterns and (iii) empirical knowledge on the epidemiology of influenza. For model validation we compare the simulation outcomes with empirical knowledge regarding (i) the shape of the epidemic curve, overall infection rate and reproduction number, (ii) age-dependent infection rates and time of infection, (iii) spatial patterns.
  
  
  RESULTS
  The simulation model is capable of reproducing the shape of the 2003/2004 H3N2 epidemic curve of Switzerland and generates an overall infection rate (14.9 percent) and reproduction numbers (between 1.2 and 1.3), which are realistic for seasonal influenza epidemics. Age and spatial patterns observed in empirical data are also reflected by the model: Highest infection rates are in children between 5 and 14 and the disease spreads along the main transport axes from west to east.
  
  
  CONCLUSIONS
  We show that finding evidence for the validity of simulation models of influenza spread by challenging them with seasonal influenza outbreak data is possible and promising. Simulation models for pandemic spread gain more credibility if they are able to reproduce seasonal influenza outbreaks. For more robust modelling of seasonal influenza, serological data complementing sentinel information would be beneficial.
authors.affiliation: Institute for Environmental Decisions, Natural and Social Science Interface, ETH Zurich, Universitaetsstrasse 22, 8092 Zurich, Switzerland. timo.smieszek@env.ethz.ch
authors.forename: Timo
authors.initials: T
authors.lastname: Smieszek
authors.forename: Michael
authors.initials: M
authors.lastname: Balmer
authors.forename: Jan
authors.initials: J
authors.lastname: Hattendorf
authors.forename: Kay W
authors.initials: KW
authors.lastname: Axhausen
authors.forename: Jakob
authors.initials: J
authors.lastname: Zinsstag
authors.forename: Roland W
authors.initials: RW
authors.lastname: Scholz
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D058872:Epidemics; D005260:Female; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000635:transmission*; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015203:Reproducibility of Results; D013557:Switzerland / Q000453:epidemiology; D055815:Young Adult