Short Wave - Coronavirus Can Live On Surfaces For Days. What That Really Means

Episode Date: March 18, 2020

It actually behaves much like other viruses in that regard. NPR health correspondent Allison Aubrey has more on what we know, what we don't, and tips on how to keep surfaces clean. More from her reporting is here. Following all of NPR's coverage of the coronavirus pandemic here. Email the show at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. So you might have heard that there's new evidence that coronavirus can live in the air for several hours and live on some surfaces for up to two to three days. And that sounds kind of scary, but it's actually not that unusual. So to put it all in perspective, we have NPR health correspondent, Alison Aubrey with us. Hey, Allison. Hey, Allison. Okay, so we're talking about a study led by science. at a NIH lab. What's the main finding?

The new study looked at the novel coronavirus in a laboratory setting and found the virus can survive for up to 72 hours on certain surfaces. We'll get to which of those surfaces later. But like you said, there are a few caveats here. For example, the study was done in a lab where the conditions are very stable. In the real world, factors such as sunlight can kill off viruses faster. Sunlight, a literal and figurative disinfectant, Allison, you know? That's right. Okay, so sit tight and we'll explain more about how long the virus lives in the environment, what we know now about how coronavirus is transmitted,

and some tips for keeping surfaces and yourself clean. I'm Maddie Safaya, and this is Shortwave, the Daily Science podcast from NPR. Okay, Allison, the first thing we've got to say is that this is one small study that has not been peer reviewed yet. That's right. And that's something we're likely to see more and more of because scientists are trying to learn a lot about this virus as fast as they can and get that information out to everybody.

Yes. I mean, I think it's a really important thing to keep in mind here. We still have so much to learn about this virus. But these findings are important. I mean, this one is all about how long this novel virus can survive outside the body. Before this, we had estimates based on how other coronaviruses behave. But this is the first study by scientists at a federal laboratory to test the actual virus causing this current pandemic. And it's obviously quite useful to know how long a virus can live on a surface. Because when a person coughs and sneezes, the virus can land on doorknabs, elevator buttons, handrails, countertops, you name it,

and potentially spread the virus to anybody who touches these surfaces. That's right. So to test the survival time on various surfaces, scientists at the Rocky Mountain Laboratories in Montana, it's part of the National Institutes of Health, conducted a series of experiments comparing this virus with the SARS virus, a similar coronavirus that led to an outbreak back in 2003. And what they found is that the novel coronavirus can survive on hard surfaces, such as plastic and stainless steel for up to 72 hours and on cardboard for up to 24 hours. We're talking about potentially days of infectivity on some of these surfaces. That is one of the authors of the study. That's James Lloyd Smith. And what they found for this novel coronavirus is that it behaves very similarly to the SARS virus. And we should point out that by those later time points, that 72 hours, there wasn't a ton of viable virus left. That said, do we know if people can become infected with the novel coronavirus?

if they touch a contaminated surface? Well, we do know that when an infected person coughs or sneezes out, little virus-leaded in respiratory droplets, as they're known, and then you happen to be standing within about six feet of that. Those droplets can land in your nose or mouth and you can become sick. Another possible route of transmission is that an infected person sneezes on a surface, like we said, a doorknob, an elevator button. You touch that.

Then you touch your eyes, nose, or mouth. those are possible entry points for the virus. The CDC says this is not thought to be the main way the virus spreads, but it is possible. Right. So that's why knowing about the two to three days of possible survival on a surface is important. But these tests were done in a lab, which is different than the real world, right? Absolutely. I mean, I'd say these findings establish a ballpark, you know, an estimate for the survivability of the virus. As you point out, it's a laboratory setting. The conditions are carefully controlled and very constant.

But in the real world, conditions fluctuate. So things like temperature, humidity, and light vary. And the survivability may vary too. For instance, direct sunlight can kill viruses. So the virus contaminates a sunny windowsill or a countertop in the sun. It may not last as long. Gotcha, gotcha. Okay.

So these scientists, they not only tested the survival. of the virus on surfaces, they tested it in the air, too. That's right. They wanted to see how long the virus could remain viable in the air. But these were not respiratory particles that a person sneezed out or coughed out. These were little bits of the virus. They used a machine to aerosolize the virus. Here's Lloyd Smith again. What these experiments show is that the virus can remain viable floating in the air for some number of hours.

The experiments went out to three days. hours and, you know, there were still viable viruses present. And what he told me is that this experiment definitely does not prove that people have been infected this way by particles of virus that float in the air, what scientists sometimes call aerosolized or airborne transmission. Right, right. And that is something that can be kind of confusing. So let's clear up the term airborne transmission. When scientists talk about airborne transmission, they're talking about how certain microbes can hang out in the air for a long time, sometimes traveling quite a distance

in the form of very, very small particles called aerosols. Yes. And those little particles can be inhaled by other people, sometimes hours after they've left the room, and that's enough to get them sick. The measles virus is like that. It's one of the reasons it's one of the most contagious pathogens on Earth. And so far, that is not what doctors think is going on with coronavirus. That's right. In fact, what we know about this coronavirus is that transmission seems to happen when people are in close quarters.

The evidence so far is that people with coronavirus sneeze or they cough. They release these larger droplets, as we talked about, these bits of virus that are encapsulated in saliva or mucus that you sneeze or cough out. And maybe, as we discussed, landing on another person or a contaminated surface. Now, these droplets technically travel through the air. But that's not airborne transmission. Right. And we're still figuring this all out. There's still a lot to learn about how coronavirus spreads.

There are a lot of things we don't know, so we do not yet know what the infectious dose is. And when I talked to Lloyd Smith, he brought up another point. He says what remains unknown is what dose or amount of the coronavirus is necessary to infect someone. Like exactly how many viral particles need to get into somebody's airway to initiate an infection? Right. That's something I'm really looking forward to learning because it is so important. We need to know how much virus it takes to get another person sick because it helps us plan and develop a prevention strategy. Yeah. I mean, part of the reason, say, measles is so contagious is because it doesn't take very much of the virus to get people sick. So to your point. So like you said earlier, in all these experiments, the new coronavirus is acting very similar to SARS, which, which is. Which leads to an interesting question, which is why has this virus spread much more widely than SARS ever did?

Right. I mean, that's kind of a million dollar question. You point out, SARS eventually sort of petered out. This virus is circling the globe. It is causing a pandemic. Lloyd Smith says there could be multiple reasons. Things like the apparent ability of this novel virus to be transmitted and shed by people who aren't showing severe symptoms or may. not be showing symptoms at all, which makes this virus much harder to contain. It's also worth pointing out that both of these viruses spread in hospital settings. It seems like the novel coronavirus is spreading more outside hospitals than SARS did. So you've got more cases of what we call person-to-person spread in communities. So that's really something to keep an eye on. And given all this, it makes this advice that we've been hearing for weeks now ever more important,

Right? And you know what I'm about to say here, right, Maddie? I know it. I can't wait. Wash your hands, right? Yes. Wash your hands. Don't touch your face. Sanitize your surfaces. These are the best way to protect yourself. And if you need to use hand sanitizer, make sure it's at least 60% alcohol. Yeah. And if you don't have to go out there in the world right now, don't.

It's called social distancing and it is the cool thing to do right now. I'm recording this episode from my closet. it. But if you absolutely have to go out in the world, wash your hands a lot, and that includes your third hand, your phone. Yes, because once your hands are clean and your surfaces are clean, then you pick up that cell phone. Well, guess what? It can be covered in potential pathogens. So disinfect your phone. I think our phones are often held close to our eyes, our nose, our mouth, where germs can enter the body. So wipe it down. Just use disinfecting wipes. like bleach wipes or alcohol wipes.

Alison, let's not act like you can get your hands on Clorox wipes right now. You know what I mean? Grocery stores are a barren wasteland. Yeah, you're right. I mean, these wipes are hard to come by at the moment, but you can buy a disinfecting spray. There's a list from the Center for Bioside Chemistries. It includes products, some of which you've heard of, some of which you haven't, a whole bunch of them there. You can also make your own bleach-based spray per the CDC's instructions.

It's pretty easy. Okay, Allison, we appreciate you. Thanks for the info. All right. Thanks, Maddie. In the notes for this episode, there's a link to Allison's story where you can find all the info we talked about here. And another link where you can follow all of NPR's coverage on the coronavirus pandemic. This episode was produced by Brent Bachman and edited by Viet Le.

I'm Maddie Safaya. Thanks for listening to Shortwave from NPR.