Exposure to influenza virus aerosols during routine patient care.
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.
Section on Infectious Diseases, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA. wbischof@wfubmc.edu
Werner E
WE
Bischoff
Katrina
K
Swett
Iris
I
Leng
Timothy R
TR
Peters
D000293:Adolescent; D000328:Adult; D000336:Aerosols; D000391:Air Microbiology; D002648:Child; D002675:Child, Preschool; D003371:Cough / Q000821:virology; D003428:Cross Infection / Q000473:pathology / Q000821:virology; D004636:Emergency Service, Hospital; D005260:Female; D006282:Health Personnel; D006801:Humans; D017758:Infectious Disease Transmission, Patient-to-Professional; D007251:Influenza, Human / Q000635:transmission*; D019570:Inhalation Exposure / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000821:virology; D009975:Orthomyxoviridae / Q000235:genetics / Q000302:isolation & purification*; D012367:RNA, Viral / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012720:Severity of Illness Index; D012912:Sneezing; D011795:Surveys and Questionnaires; D062606:Tertiary Care Centers; D019562:Viral Load; D055815:Young Adult
D000336:Aerosols; D012367:RNA, Viral