Until now, most people thought you caught the flu after being exposed to droplets from an infected person’s coughs or sneezes, or by touching contaminated surfaces.
But a study released last month in the Proceedings of the National Academy of Sciences reveals that we may pass the flu to others just by breathing.
The study — which included researchers who are now working at San Jose State University and UC Berkeley — offers new evidence on the importance of the flu’s airborne qualities and how it can easily be transmitted to others. Researchers found large quantities of infectious viruses in the breath exhaled by those suffering from the flu.
“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,” Sheryl Ehrman, who is now dean of the College of Engineering at San Jose State University, said in a statement. “Staying home and out of public spaces could make a difference in the spread of the influenza virus.”
Ehrman said the study was launched at the University of Maryland during the flu season of December 2012 through March 2013. Researchers including Jovan Pantelic, who now works at UC Berkeley, recruited 178 volunteers, mostly students, who had shown flu symptoms within three days of the flu’s onset.
Over those four months, researchers captured and characterized the flu virus in 142 of the volunteers with confirmed cases of the flu while they breathed naturally, talked, coughed or sneezed.
The researchers then assessed the severity of naturally occurring flu aerosols — tiny droplets that stay suspended in the air for a long time.
The study’s participants provided 218 swabs from their nasopharynx, the upper part of the throat that lies just behind the nose. They also provided 218 samples — over a period of 30 minutes — of exhaled breath, spontaneous coughing, and sneezing on the first, second, and third days after the onset of flu symptoms.
The analysis of the infectious virus recovered from these samples showed that a significant number of flu patients routinely shed an infectious virus into tiny aerosol particles that can be transmitted through the air.
Surprisingly, the study suggested that coughing or sneezing was not necessary to be infectious.
“We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing,” Dr. Donald Milton, professor of environmental health in the University of Maryland School of Public Health, said in a statement.
“People with flu generate infectious aerosols even when they are not coughing, and especially during the first days of illness,” he said. “So when someone is coming down with influenza, they should go home and not remain in the workplace and infect others.”
The researchers believe that their findings could be used to improve mathematical models about the risk of airborne flu transmission from people with flu symptoms, and may help control and reduce the impact of influenza epidemics and pandemics.
Improvements also could be made to ventilation systems to reduce transmission risk in offices, school classrooms and subway cars, for example, the study said.
For now, the researchers — and public health experts — say everyone should heed the advice to stay home, if possible, when they’re starting to come down with the flu to prevent the virus from spreading.
And while getting a flu vaccine isn’t a guarantee that you won’t get the flu, experts say it provides some protection and helps reduce the chances that you’ll get seriously ill from the flu.
Which foods can help you fight the flu?
Some are advising that in addition to the usual rules about getting your flu shot, washing your hands more often and getting enough sleep, you should also think about shifting your diet towards foods that may boost your immunity.
“When we’re sick, we don’t want to eat and don’t want to drink, but you need to continue to eat and give your body the nutrients and energy you need for the immune system to function properly,” Michael P. Angarone, D.O., assistant professor of infectious diseases and medical education at Northwestern University’s Feinberg School of Medicine told Fox
But here are some foods you may not have thought about in terms of helping shield you during what is being called a deadly flu season. Try increasing the probiotics in your menu, because that boosts the health and wellness of your gut, which may aid your immune system. It’s pretty easy to do, too. Why not have some Greek yogurt at breakfast and dress up your hot dog with sauerkraut?
“Probiotics are healthy microorganisms that can help support bacterial balance in the gut,” dietitian Jaime Mass, R.D.N., L.D. told Fox.
Another good immune booster is ginger tea, a zesty and soothing choice for cold weather. In a review published in the International Journal of Preventative Medicine, as Today noted.
Another easy pick is blueberries, which are bursting with antioxidants that may help treat and prevent coughs and colds, advised Today.
You might also want to stock up on salmon, chicken, lamb, spinach, sesame seeds, lentils, and chickpeas, all of which have loads of zinc. While the jury is still out on how effective zinc is in terms of reducing cold symptoms, some studies have showed promise.
Researchers found that zinc, in comparison to a placebo, significantly reduced the severity and duration of symptoms when taken within 24 hours of the onset of cold symptoms. They also found that children who took 15 mg of zinc daily for seven months were a lot less likely to catch a cold during flu season.