Does breathing spread the influenza virus?

By ANNA CHEN | February 1, 2018


As college students, Hopkins students know all too well how dreadful — and how easy — it is to contract some sort of virus, one that will keep you up all night coughing your lungs out or force your runny nose through two full boxes of tissues a day. The constant sleep deprivation and nutrition-deficient meals definitely do not help. Getting sick in college is the worst.

And yet it seems that no matter what precautions students take, wiping the apartment down with Clorox wipes, refusing to share food with a sick friend or bringing hand sanitizer everywhere they go, they still end up getting that bug that is going around. Why?

This past week, researchers at the University of Maryland (UMD) published findings that shed some light on this matter.

Led by Dr. Donald Milton, professor of environmental health at the University of Maryland School of Public Health, the research team found that people with an infectious virus, such as the influenza virus, contaminate the air around them by merely breathing.

“[These viruses] 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,” Milton said in a press release.

With funding by the Center of Disease Control (CDC) and National Institutes of Health (NIH), the researchers at UMD collaborated with scientists from San Jose State University, Missouri Western State University and University of California, Berkeley and   found influenza virus in the exhaled breath of 142 confirmed cases of subjects with influenza. This exhaled breath included natural breathing, talking, and spontaneous sneezing and coughing.

They collected a total of 218 nasopharyngeal swabs and 218 30-minute breath samples on the first, second and third days of symptom onset. Upon analyzing the samples, both viral RNA and infectious influenza viruses that present a significant risk of airborne transmission were detected and characterized.

Of the 23 aerosol samples obtained in the absence of coughing, 11 (48 percent) had detectable viral RNA, and eight of those 11 contained infectious viruses. This suggests that coughing is not necessary to generate infectious aerosol particles.

In addition, scientists were surprised to find that the few recorded sneezes did not contain greater numbers of viral RNA particles in the generated aerosols than exhaled breath. Thus, contrary to popular belief, sneezing and coughing do not seem to make important contributions to the amount of influenza viruses in aerosols, at least not any more than breathing does.

The conclusions of this study suggest that the usual precautions people take, such as disinfecting surfaces and asking others to cover their mouths when they cough or sneeze, although important, do not provide enough protection from the flu.

It seems that just by breathing, people with the flu can pass the virus to others, and worse, to those who are vulnerable and likely to be among the 20-30,000 lives claimed by influenza in the United States each year.

Although this conclusion sounds dire, there is still good news. The flu virus may be more difficult to control than expected, but it is not entirely unavoidable.

In an interview with The News-Letter, Keri Althoff, associate professor of epidemiology at the Bloomberg School of Public Health, expressed her thoughts on the issue.

Althoff wanted to remind students that although it may not be foolproof, there are effective ways to prevent the flu.

“Get an influenza vaccine, because even when it is not a perfect match, some protection is better than none. Stay home if you are sick, particularly if you have a fever, and wash your hands often when you, or people around you, are sick,” Althoff said.

For those who do contract the virus, she also provides additional advice for students to catch up with the class content they miss if they become ill.

“This plan includes outreach to your professors and your peers, and it may help you feel less stress, rest easier and provide a roadmap [to] getting caught up on coursework when you recover,” Althoff said.

So although the researchers’ findings at UMD make the flu seem inescapable, being aware of how infectious diseases are transmitted and taking extra precautions to prevent contracting and spreading them do go a long way. Knowing how easily the flu spreads, learning to be extra careful about it and planning ahead will only be beneficial and would be a good start to a healthier, happier community.

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