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Pandemic Advances Scientific Understanding Of Viruses' Air Transmission


As the year wraps up, we're taking a look back at some of 2020's major events, and one of the most remarkable scientific advances this year came in our understanding of how respiratory viruses can be transmitted from one person to another through the air. The coronavirus pandemic obviously made this an urgent question. And NPR's Nell Greenfieldboyce reports that old scientific ideas quickly got thrown out of the window.

NELL GREENFIELDBOYCE, BYLINE: For decades, the prevailing idea about respiratory viruses was that some were airborne and some just weren't.

LINSEY MARR: So back in January, the understanding of how viruses spread through the air was really primitive and incorrect.

GREENFIELDBOYCE: Linsey Marr is a researcher at Virginia Tech who studies virus transmission. She says textbooks and research papers said an airborne virus was something like measles. It can be breathed out in tiny particles called aerosols that hang in the air. Those aerosols can travel long distances, from room to room. All of that was very different from nonairborne viruses, like flu and the common cold. Those were thought to spread through coughs and sneezes, big droplets that travel just a few feet. Marr says this whole simplistic picture was just wrong.

MARR: There were a very small number of people in the world, I think, who really understood at that time how viruses spread through the air.

GREENFIELDBOYCE: And these people realized that the new coronavirus might be airborne - at short distances, that is. If people talked or sang, the virus could be in small particles, as well as the big droplets in coughs. And in a poorly ventilated space, these particles could build up. As the coronavirus outbreak took off, these experts started making a lot of noise about this, and people paid attention. Marr says she thought it would take 30 years for more nuanced ideas about airborne transmission to gain widespread acceptance, but it's happened in months.

MARR: It's been pretty wild to see airborne transmission of viruses become big news.

GREENFIELDBOYCE: Scientific studies came super fast. Josh Santarpia is a researcher at the University of Nebraska Medical Center.

JOSH SANTARPIA: We're not even 12 months in, and we know things about this virus that, you know, we don't know about some viruses that we've had around for decades.

GREENFIELDBOYCE: His medical center took care of some of the first people with coronavirus in the United States. Santarpia recalls standing at the end of their beds with a device that collected air while they talked or breathed. His lab then analyzed the tiny airborne droplets, looking for the genetic signature of the coronavirus.

SANTARPIA: We were getting positives, more than one positive, in the air samples. And I can't say the words that I said (laughter) because you're going to broadcast this, but I was shocked.

GREENFIELDBOYCE: Signs of the virus were in such tiny particles. He worried that nothing less than the most protective masks could stop it. Soon, though, studies showed that even basic cloth masks were able to reduce the amount of virus that gets out into the air, and suddenly mask-wearing became routine. Santarpia was floored at how ventilation became part of the normal daily conversation.

SANTARPIA: You know, how well ventilated is the space? Should I be spending time inside or outside? You know, how much - all these things. It's changed so much about the way we view the world.

GREENFIELDBOYCE: The question is, will this be a lasting change? Donald Milton is a researcher at the University of Maryland School of Public Health. He's spent years showing how better ventilation in dorms or offices is associated with a lower risk of respiratory disease transmission. He says we need to figure out engineering solutions to improve the safety of indoor spaces, like getting better ventilation, using air filters, even using special lights up by a room's ceiling to disinfect circulating air.

DONALD MILTON: I want to see us understand how it is that you can make a restaurant a safe place to be during flu season and during a pandemic. I think it's doable.

GREENFIELDBOYCE: But he's afraid that once vaccines get this virus in check, people will lose interest - at least until the next pandemic.

Nell Greenfieldboyce, NPR News.

(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright NPR.

Nell Greenfieldboyce is a NPR science correspondent.
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