Breathing is enough to pass the flu virus along, according to a study published in the Proceedings of the National Academy of Sciences.
The finding shed new light on how the virus is passed, that is, not just through exposure to droplets from an infected person’s cough or sneezes, or touching contaminated surfaces.
The research by San Jose State University and UC Berkeley was done at the University of Maryland during the flu season of December 2012 to March 2013.
Based on 142 student volunteers, who had shown symptoms within three days of contracting flu, the researchers extracted 218 swabs from the upper part of the throat just behind the nose from the volunteers.
The researchers also collected 218 samples of the students’ breath, and spontaneous coughing and sneezing on the first, second and third days after the onset of flu symptoms. Cultures of the air breathed out by the patients were then cultured.
Half of the breath samples had detectable viral flu in them, suggesting that coughing or sneezing isn’t the only way to spread flu.
“We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing,” said Dr Donald Milton, professor of environmental health in the University of Maryland School of Public Health.
“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.”
Dr. Milton also cited previous studies that showed that the flu virus lingers in the air, further driving home the message that “staying home could make a real difference” to those coming down with the flu.
The researchers hope that their findings could be used to improve ventilation systems and reduce flu’s transmission risk.