title: Use of a human influenza challenge model to assess person-to-person transmission: proof-of-concept study.
abstract: BACKGROUND
  Influenza transmission in humans remains poorly understood. In particular, the relative contribution of contact, large droplet, and aerosol transmission is unknown. The aims of this proof-of-concept study were to determine whether an experimentally induced influenza infection is transmissible between humans and whether this would form a viable platform for future studies.
  
  
  METHODS
  In a quarantine facility, healthy volunteers ("donors") were inoculated with A/Wisconsin/67/2005 (H3N2) influenza virus via intranasal drops. On study days 2 and 3 "recipient" volunteers were exposed to donors under close living conditions. Volunteers socialized for 30 hours during a 2-day period. Infection was confirmed by ≥1 positive results from polymerase chain reaction, virus culture, or serology.
  
  
  RESULTS
  After inoculation, 4 of 9 donors developed symptoms consistent an influenza-like illness (ILI) and 7 of 9 were proven to be influenza-infected. After exposure, 4 of 15 recipients developed symptoms of ILI and 3 of 15 were proven to be infected. Serum collected within 2 days of study initiation indicated that 1 donor and 3 recipients were seropositive at study initiation. After adjustment for preexposure immunity, the overall secondary attack rate was 25% (3 of 12).
  
  
  CONCLUSIONS
  Experimental human exposure studies offer an attractive potential method for answering outstanding questions related to influenza transmission and the evaluation of interventions to reduce it.
authors: Division of Epidemiology and Public Health, University of Nottingham. ben.killingley@nottingham.ac.uk
authors: Ben
authors: B
authors: Killingley
authors: Joanne E
authors: JE
authors: Enstone
authors: Jane
authors: J
authors: Greatorex
authors: Anthony S
authors: AS
authors: Gilbert
authors: Rob
authors: R
authors: Lambkin-Williams
authors: Simon
authors: S
authors: Cauchemez
authors: Jacqueline M
authors: JM
authors: Katz
authors: Robert
authors: R
authors: Booy
authors: Andrew
authors: A
authors: Hayward
authors: John
authors: J
authors: Oxford
authors: Carolyn B
authors: CB
authors: Bridges
authors: Neil M
authors: NM
authors: Ferguson
authors: Jonathan S
authors: JS
authors: Nguyen Van-Tam
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology / Q000302:isolation & purification; D007251:Influenza, Human / Q000097:blood / Q000175:diagnosis / Q000635:transmission*; D008297:Male; D008954:Models, Biological
chemical_list: D000914:Antibodies, Viral