Journal of Infectious Diseases
Volume 207 Issue 7   April 1, 2013
http://www.journals.uchicago.edu/toc/jid/current

MAJOR ARTICLES AND BRIEF REPORTS
VIRUSES
Exposure to Influenza Virus Aerosols During Routine Patient Care
Werner E. Bischoff, Katrina Swett, Iris Leng, and Timothy R. Peters
J Infect Dis. (2013) 207(7): 1037-1046 doi:10.1093/infdis/jis773
http://jid.oxfordjournals.org/content/207/7/1037.abstract

Abstract
Background. Defining dispersal of influenza virus via aerosol is essential for the development of prevention measures.

Methods. During the 2010–2011 influenza season, subjects with influenza-like illness were enrolled in an emergency department and throughout a tertiary care hospital, nasopharyngeal swab specimens were obtained, and symptom severity, treatment, and medical history were recorded. Quantitative impaction air samples were taken not ≤0.305 m (1 foot), 0.914 m (3 feet), and 1.829 m (6 feet) from the patient’s head during routine care. Influenza virus was detected by rapid test and polymerase chain reaction.

Results. Sixty-one of 94 subjects (65%) tested positive for influenza virus. Twenty-six patients (43%) released influenza virus into room air, with 5 (19%) emitting up to 32 times more virus than others. Emitters surpassed the airborne 50% human infectious dose of influenza virus at all sample locations. Healthcare professionals (HCPs) were exposed to mainly small influenza virus particles (diameter, <4.7 µm), with concentrations decreasing with increasing distance from the patient’s head (P < .05). Influenza virus release was associated with high viral loads in nasopharyngeal samples (shedding), coughing, and sneezing (P < .05). Patients who reported severe illness and major interference with daily life also emitted more influenza virus (P < .05).

Conclusions. HCPs within 1.829 m of patients with influenza could be exposed to infectious doses of influenza virus, primarily in small-particle aerosols. This finding questions the current paradigm of localized droplet transmission during non–aerosol-generating procedures.