title: The environmental deposition of influenza virus from patients infected with influenza A(H1N1)pdm09: Implications for infection prevention and control.
abstract: In a multi-center, prospective, observational study over two influenza seasons, we sought to quantify and correlate the amount of virus recovered from the nares of infected subjects with that recovered from their immediate environment in community and hospital settings. We recorded the symptoms of adults and children with A(H1N1)pdm09 infection, took nasal swabs, and sampled touched surfaces and room air. Forty-two infected subjects were followed up. The mean duration of virus shedding was 6.2 days by PCR (Polymerase Chain Reaction) and 4.2 days by culture. Surface swabs were collected from 39 settings; 16 (41%) subject locations were contaminated with virus. Overall, 33 of the 671 (4.9%) surface swabs were PCR positive for influenza, of which two (0.3%) yielded viable virus. On illness Day 3, subjects yielding positive surface samples had significantly higher nasal viral loads (geometric mean ratio 25.7; 95% CI 1.75, 376.0, p=0.021) and a positive correlation (r=0.47, p=0.006) was observed between subject nasal viral loads and viral loads recovered from the surfaces around them. Room air was sampled in the vicinity of 12 subjects, and PCR positive samples were obtained for five (42%) samples. Influenza virus shed by infected subjects did not detectably contaminate the vast majority of surfaces sampled. We question the relative importance of the indirect contact transmission of influenza via surfaces, though our data support the existence of super-spreaders via this route. The air sampling results add to the accumulating evidence that supports the potential for droplet nuclei (aerosol) transmission of influenza.
authors.affiliation: Health Protection and Influenza Research Group, Division of Public Health and Epidemiology, University of Nottingham, Nottingham, UK.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Killingley
authors.affiliation: Public Health England, Clinical Microbiology and Public Health Laboratory, Cambridge, UK.
authors.forename: Jane
authors.initials: J
authors.lastname: Greatorex
authors.affiliation: The Roslin Institute, University of Edinburgh, Edinburgh, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Digard
authors.affiliation: The Roslin Institute, University of Edinburgh, Edinburgh, UK.
authors.forename: Helen
authors.initials: H
authors.lastname: Wise
authors.affiliation: Public Health England, Clinical Microbiology and Public Health Laboratory, Cambridge, UK.
authors.forename: Fayna
authors.initials: F
authors.lastname: Garcia
authors.affiliation: Public Health England, Clinical Microbiology and Public Health Laboratory, Cambridge, UK.
authors.forename: Harsha
authors.initials: H
authors.lastname: Varsani
authors.affiliation: MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Cauchemez
authors.affiliation: Health Protection and Influenza Research Group, Division of Public Health and Epidemiology, University of Nottingham, Nottingham, UK.
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Enstone
authors.affiliation: Department of Infection and Population Health, University College London, London, UK.
authors.forename: Andrew
authors.initials: A
authors.lastname: Hayward
authors.affiliation: Public Health England, Clinical Microbiology and Public Health Laboratory, Cambridge, UK.
authors.forename: Martin D
authors.initials: MD
authors.lastname: Curran
authors.affiliation: Clinical and Experimental Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Read
authors.affiliation: Department of Respiratory Medicine, Nottingham University Hospitals NHS Trust, Nottingham, UK.
authors.forename: Wei S
authors.initials: WS
authors.lastname: Lim
authors.affiliation: Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, UK.
authors.forename: Karl G
authors.initials: KG
authors.lastname: Nicholson
authors.affiliation: Health Protection and Influenza Research Group, Division of Public Health and Epidemiology, University of Nottingham, Nottingham, UK. Electronic address: jvt@nottingham.ac.uk.
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Nguyen-Van-Tam
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D018562:Disease Transmission, Infectious / Q000517:prevention & control; D004783:Environmental Microbiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D017053:Infection Control / Q000379:methods; D053118:Influenza A Virus, H1N1 Subtype / Q000302:isolation & purification*; D007251:Influenza, Human / Q000517:prevention & control* / Q000635:transmission / Q000821:virology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009666:Nose / Q000821:virology*; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D013997:Time Factors; D014776:Virus Cultivation; D017201:Virus Shedding; D055815:Young Adult
keywords: Control; Deposition; Environmental; Infection; Influenza