Flu may be spread just by breathing, new study shows; coughing and sneezing not required

January 18, 2018, University of Maryland
A study participant sits in the Gesundheit II machine, which is used to capture and analyze influenza virus in exhaled breath at the University of Maryland School of Public Health. Credit: University of Maryland

It is easier to spread the influenza virus (flu) than previously thought, according to a new University of Maryland-led study released today. People commonly believe that they can catch the flu by exposure to droplets from an infected person's coughs or sneezes or by touching contaminated surfaces. But, new information about flu transmission reveals that we may pass the flu to others just by breathing.

The study "Infectious virus in of symptomatic seasonal influenza cases from a college community," published in the Proceedings of the National Academy of Sciences, provides new evidence for the potential importance of because of the large quantities of infectious virus researchers found in the exhaled breath from people suffering from flu.

"We found that contaminated the air around them with infectious virus just by breathing, without coughing or sneezing," explained Dr. Milton, M.D., MPH, professor of environmental health in the University of Maryland School of Public Health and lead researcher of this study. "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."

Researchers from the University of Maryland, San Jose State University, Missouri Western State University and University of California, Berkeley contributed to this study funded by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health.

Dr. Milton and his research team captured and characterized influenza virus in exhaled breath from 142 confirmed cases of people with influenza during natural breathing, prompted speech, spontaneous coughing, and sneezing, and assessed the infectivity of naturally occurring influenza aerosols. The participants provided 218 nasopharyngeal swabs and 218 30-minute samples of exhaled breath, spontaneous coughing, and sneezing on the first, second, and third days after the onset of symptoms.

The analysis of the infectious virus recovered from these samples showed that a significant number of flu patients routinely shed infectious virus, not merely detectable RNA, into particles small enough to present a risk for airborne transmission.

Surprisingly, 11 (48%) of the 23 fine aerosol samples acquired in the absence of coughing had detectable viral RNA and 8 of these 11 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 shedding in aerosols.

"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," said 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 ."

According to the authors, the findings could be used to improve mathematical models of the risk of airborne influenza transmission from people with symptomatic illness and to develop more effective public health interventions and to control and reduce the impact of epidemics and pandemics. Improvements could be made to ventilation systems to reduce transmission risk in offices, school classrooms and subway cars, for example. Meanwhile, we can all heed the advice to stay home, if possible, when we are beginning to get sick to prevent even greater numbers of flu cases. And, get vaccinated—it is not perfect but does prevent a significant amount of severe illness.

Explore further: Study provides new clues to how flu virus spreads

More information: Jing Yan et al. Infectious virus in exhaled breath of symptomatic seasonal influenza cases from a college community, bioRxiv (2017). DOI: 10.1101/194985 , https://www.biorxiv.org/content/early/2018/01/03/194985 ; PNAS http://www.pnas.org/content/early/2018/01/17/1716561115.abstract

Related Stories

Study provides new clues to how flu virus spreads

March 7, 2013
People may more likely be exposed to the flu through airborne virus than previously thought, according to new research from the University of Maryland School of Public Health. The study also found that when flu patients wear ...

Repeated influenza vaccination helps prevent severe flu in older adults

January 8, 2018
Repeated vaccination for influenza in older adults reduced the severity of the virus and reduced hospital admissions, found new research published in CMAJ (Canadian Medical Association Journal)

Patients can emit small, influenza-containing particles into the air during routine care

January 31, 2013
A new study suggests that patients with influenza can emit small virus-containing particles into the surrounding air during routine patient care, potentially exposing health care providers to influenza. Published in The Journal ...

Virulence factor made by influenza virus is potential target for vaccine drug development

August 14, 2017
A new study describes how NS1, a protein produced by influenza A viruses, suppresses the body's immune responses to viral infection. Researchers present the potential to develop a live attenuated vaccine based on an engineered ...

Ferrets, pigs susceptible to H7N9 avian influenza virus

May 23, 2013
Chinese and U.S. scientists have used virus isolated from a person who died from H7N9 avian influenza infection to determine whether the virus could infect and be transmitted between ferrets. Ferrets are often used as a mammalian ...

Recommended for you

Tibetan sheep highly susceptible to human plague, originates from marmots

August 16, 2018
In the Qinghai-Tibet plateau, one of the region's highest risk areas for human plague, Himalayan marmots are the primary carriers of the infectious bacterium Y. pestis. Y. pestis infection can be transmitted to humans and ...

Autoimmunity plays role in development of COPD, study finds

August 16, 2018
Autoimmunity plays a role in the development of chronic obstructive pulmonary disease (COPD), according to a study led by Georgia State University and Vanderbilt University Medical Center that analyzed human genome information ...

Scientists identify nearly 200 potential tuberculosis drug targets

August 16, 2018
Tuberculosis is one of the top 10 causes of death worldwide. Nearly 2 million people die every year from this infectious disease, and an estimated 2 billion people are chronically infected. The only vaccine, developed almost ...

Reliable point-of-care blood test can help prevent toxoplasmosis

August 16, 2018
A recent study, performed in Chicago and Rabat, Morocco, found that a novel finger-prick test for infection with the parasite Toxoplasma gondii during pregnancy—and many other potential applications—is 100 percent sensitive ...

First mouse model to mimic lung disease could speed discovery of more effective treatments

August 16, 2018
The biggest hurdle to finding effective therapies for idiopathic pulmonary fibrosis (IPF) – a life-threatening condition in which the lungs become scarred and breathing is increasingly difficult – has been the inability ...

Anticancer drug offers potential alternative to transplant for patients with liver failure

August 15, 2018
Patients suffering sudden liver failure could in the future benefit from a new treatment that could reduce the need for transplants, research published today shows.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.