title: Entry and exit screening of airline travellers during the A(H1N1) 2009 pandemic: a retrospective evaluation.
abstract: OBJECTIVE
  To evaluate the screening measures that would have been required to assess all travellers at risk of transporting A(H1N1)pdm09 out of Mexico by air at the start of the 2009 pandemic.
  
  
  METHODS
  Data from flight itineraries for travellers who flew from Mexico were used to estimate the number of international airports where health screening measures would have been needed, and the number of travellers who would have had to be screened, to assess all air travellers who could have transported the H1N1 influenza virus out of Mexico during the initial stages of the 2009 A(H1N1) pandemic.
  
  
  RESULTS
  Exit screening at 36 airports in Mexico, or entry screening of travellers arriving on direct flights from Mexico at 82 airports in 26 other countries, would have resulted in the assessment of all air travellers at risk of transporting A(H1N1)pdm09 out of Mexico at the start of the pandemic. Entry screening of 116 travellers arriving from Mexico by direct or connecting flights would have been necessary for every one traveller at risk of transporting A(H1N1)pdm09. Screening at just eight airports would have resulted in the assessment of 90% of all air travellers at risk of transporting A(H1N1)pdm09 out of Mexico in the early stages of the pandemic.
  
  
  CONCLUSIONS
  During the earliest stages of the A(H1N1) pandemic, most public health benefits potentially attainable through the screening of air travellers could have been achieved by screening travellers at only eight airports.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, St Michael's Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada.
authors.forename: Kamran
authors.initials: K
authors.lastname: Khan
authors.forename: Rose
authors.initials: R
authors.lastname: Eckhardt
authors.forename: John S
authors.initials: JS
authors.lastname: Brownstein
authors.forename: Raza
authors.initials: R
authors.lastname: Naqvi
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: David
authors.initials: D
authors.lastname: Kossowsky
authors.forename: David
authors.initials: D
authors.lastname: Scales
authors.forename: Julien
authors.initials: J
authors.lastname: Arino
authors.forename: Michael
authors.initials: M
authors.lastname: MacDonald
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Jennifer
authors.initials: J
authors.lastname: Sears
authors.forename: Martin S
authors.initials: MS
authors.lastname: Cetron
mesh_terms: D059028:Airports / Q000706:statistics & numerical data*; D003362:Cost-Benefit Analysis; D014943:Global Health; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype; D007251:Influenza, Human / Q000175:diagnosis* / Q000453:epidemiology; D008403:Mass Screening / Q000191:economics / Q000379:methods* / Q000706:statistics & numerical data; D008800:Mexico / Q000453:epidemiology; D058873:Pandemics; D012189:Retrospective Studies; D014195:Travel / Q000706:statistics & numerical data*