Study shows flu may be spread just by breathing

Flu breathing
© Anatoliy Cherkas

New research suggests that it is easier to spread the influenza virus than previously thought.

We all know how the flu is spread, right? A sick someone sneezes or coughs and the infected mist greets the systems of unsuspecting people nearby; likewise, we might touch a contaminated surface and then infect ourselves from there.

Which is all kinds of awful for the flu averse, but thought to be somewhat manageable with good sickness etiquette and vigilant hand-washing. But now, alas, a University of Maryland-led study finds that it is easier to spread the influenza virus: We may transmit the flu to others just by breathing.

The study, "Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community," published in the Proceedings of the National Academy of Sciences, offers more reasons why those with the flu should stay home.

"We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing," says lead researcher, Dr. Milton, M.D., MPH, professor of environmental health in the University of Maryland School (UMD) of Public Health. "People with flu generate infectious aerosols (tiny droplets that stay suspended in the air for a long time) even when they are not coughing, and especially during the first days of illness. So when someone is coming down with influenza, they should go home and not remain in the workplace and infect others."

Dr. Milton and his multi-university team of researchers studied the flu virus in exhaled breath from 142 confirmed cases of people with influenza during normal breathing, speech, coughing, and sneezing, and examined the infectivity of the influenza aerosols within; the samples were taken during the first three days after symptoms began.

(If you are wondering how they collect and study flu-tinged breath and spray, behold the "Gesundheit II machine" below, which lives at the University of Maryland School of Public Health. A shout out to flu-afflicted students who endured the contraption while sick!)

Flu machine© University of Maryland

The team was surprised to find that almost 50 percent of the samples collected not from coughing had detectable viral RNA and the majority contained infectious virus, "suggesting that coughing was not necessary for infectious aerosol generation in the fine aerosol droplets." In addition, the few sneezes observed were "not associated with greater viral RNA copy numbers in either coarse or fine aerosols, suggesting that sneezing does not make an important contribution to influenza virus shedding in aerosols," notes a statement from UMD.

"The study findings suggest that keeping surfaces clean, washing our hands all the time, and avoiding people who are coughing does not provide complete protection from getting the flu," says Sheryl Ehrman, Don Beall Dean of the Charles W. Davidson College of Engineering at San José State University. "Staying home and out of public spaces could make a difference in the spread of the influenza virus."

Learn more about the research in the video below. And remember not to breathe if you have to go out while suffering from the flu. (That's a joke, but try to stay home if you can!)

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