People Can Emit Flu Germs in Air Up to 6 Feet Away, Study Finds01/31/13
THURSDAY, Jan. 31 (HealthDay News) -- People suffering from the
flu can give off small virus particles into the air at greater
distances than previously thought, putting the health care workers
who treat these patients at increased risk for getting the virus
themselves, researchers report.
The investigators, from Wake Forest School of Medicine in North
Carolina, suggest that more studies are needed on how the flu is
spread. Infection-control guidelines for health care providers may
also need to be updated to help these workers protect their
The study was published in the current edition of the
Journal of Infectious Diseases.
"Our study offers new evidence of the natural emission of influenza and may provide a better understanding of how to best protect health care providers during routine care activities," the researchers, led by Dr. Werner Bischoff, wrote in the report.
For the study, Bischoff's team screened 94 patients with flu
symptoms who were admitted to the emergency department or inpatient
care unit of Wake Forest Baptist Medical Center during the
2010-2011 flu season. Health care providers at this hospital are
required to get a flu shot, the researchers pointed out in a Wake
Forest news release.
The investigators also collected air samples within one foot,
three feet and six feet of the patients screened. As the air
samples were taken, no aerosol-generating procedures -- such as
bronchoscopy, intubation or CPR -- were performed. The researchers
also recorded the number of times the patients coughed or sneezed
and rated the severity of these symptoms. The patients also
answered questions about their condition and how long they had been
The study authors found that 65 percent of the patients tested
positive for the flu. Of these people, 43 percent released
particles containing the virus into the air. Those who emitted the
highest levels of the flu virus into the air reported having the
worst flu-like symptoms. These patients also had the highest viral
loads in their collected samples.
Most of the flu virus found in the air samples was contained in
small particles up to six feet away from the infected patients.
Although concentrations of the virus decreased with distance, the
researchers noted that at this range health care providers may
still be exposed to infectious dosages of the flu.
Bischoff and colleagues also said that some patients were what
they called "super emitters," and gave off up to 32 times more
virus than the other patients. These people, they concluded, may be
more likely to pass the flu on to others.
Dr. Caroline Breese Hall, from the University of Rochester
School of Medicine and Dentistry in Rochester, N.Y., pointed out in
an accompanying journal editorial that the findings "question the
traditional belief that influenza is primarily spread by close
contact with an infected person or by direct contact with
And Dr. William Schaffner, chair of the department of preventive
medicine at Vanderbilt University School of Medicine in Nashville,
also commented on the study. "Influenza vaccination, although not
perfect, is the best tool we have to protect health care workers --
and their patients -- from influenza illness," he said in the news
release. Schaffner was not involved with the study.
The U.S. Department of Health and Human Services has more about
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