People can transmit the flu from six feet away, study finds

Researchers: Findings question our understanding of flu transmission

Individuals with the flu can give off virus particles into the air up to six feet away, a greater distance than previously thought, according to a new study in the Journal of Infectious Diseases.

For the study, Wake Forest University researchers screened 94 patients admitted with flu symptoms to Wake Forest Baptist Medical Center and its ED during the 2010-2011 flu season. As patients were screened, the researchers recorded the number of times they coughed and sneezed, assessed the severity of symptoms, and collected air samples taken from one foot, three feet, and six feet away from the patient.

Although flu particles were concentrated in the air immediately around a patient, they could be detected up to six feet away.

The patients who emitted the highest levels of the flu virus into the air also reported the worst flu-like symptoms. The sickest patients gave off 32 times more virus particles than the rest of the patients, making them significantly more likely to spread the illness.

Based on the findings, the researchers concluded that health care workers may be exposed to infectious doses of flu particles at work.

"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 study says.

Moreover, the study results "question the traditional belief that influenza is primarily spread by close contact with an infected person or by direct contact with infectious secretions," University of Rochester School of Medicine professor Caroline Breese Hall wrote in an accompanying editorial (Dallas, HealthDay/Philadelphia Inquirer, 2/4).

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