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A virologist answers viewer questions about coronavirus transmission

During this unprecedented crisis, we all have questions -- and the NewsHour is turning to experts for answers. In this edition of Ask Us, virologist Angela Rasmussen of Columbia University joins Amna Nawaz to take viewer questions on transmission of the novel coronavirus, including whether it can be contracted from swimming pools and street surfaces.

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  • Judy Woodruff:

    Now it's time for Ask Us.

    That's where we take your questions on the pandemic to experts who are helping us navigate these unprecedented times.

    We get your questions from our Web site, from Twitter, Instagram and Facebook.

    For the record, Facebook is a funder of the "NewsHour."

    Amna Nawaz has more.

  • Amna Nawaz:

    Thanks, Judy.

    And thanks to all of you for sending us your questions.

    Now, with so many communities opening back up across the country, a lot of you wrote in with questions on how to avoid catching or transmitting the coronavirus.

    To answer those questions and those concerns, we're joined by Angela Rasmussen. She's a virologist at Columbia University and holds a Ph.D. in microbiology.

    Angela, welcome to the "NewsHour." Thanks for being here.

  • Angela Rasmussen:

    Thanks for having me, Amna.

  • Amna Nawaz:

    So, let's jump right into these questions now.

    The first one comes from Carol Campbell. She's in Lynn, Massachusetts. She reached out to us on Facebook. And she sent us this video:

  • Carol Campbell:

    If a runner has the virus and coughs out loud, because there's no one around, does the virus linger in the air or on the ground? And, if yes, how long is the virus still viable?

  • Amna Nawaz:

    Angela, it's an important question dealing with maybe asymptomatic carriers out in public without masks. What do you say to her?

  • Angela Rasmussen:

    We don't really know in every situation how long the virus will linger in the air.

    But, in general, if you are just passing somebody on the street, walking by them, whether you're running or walking, the risk of transmission is probably fairly low.

    And the reason for that is that, in many cases where we have seen transmissions, they're usually happening in indoor environments, environments that have a lot of people or large crowds of people, where you're talking to that person for a longer duration of time.

    So, if you're just sort of incidentally passing somebody while you're out running or jogging, whether they cough or sneeze or anything else, the risk is not zero, but it's likely quite low.

  • Amna Nawaz:

    It's very good to know. We will hopefully ease some concerns out there.

    Let's move on to our next question. It comes from Nancy Pardo. She's from Mount Prospect, Illinois. And Nancy sent us this video:

  • Nancy Pardo:

    Why are other countries spraying disinfectant on the streets if it's safe to go outside? Should the U.S. be doing the same in New York, for instance?

  • Amna Nawaz:

    Angela, we have seen some of these videos in other countries, those masses of gases as people are spraying down subways and streets.

    What should we know about that? Should the U.S. be doing it?

  • Angela Rasmussen:

    So, I think that there is a difference between spraying down surfaces in a subway car vs. spraying down the road.

    To my knowledge, there is a very low, if not completely nonexistent risk from contracting coronavirus that might be on the ground, unless you're licking the ground or exposing your mouth, your nose to the bottom of your shoes.

    A subway car is a different story. In a subway car, you're going to have people breathing, producing respiratory droplets and potentially touching those surfaces. And you could potentially touch one of those surfaces, touch your hand to your mouth or nose and become infected that way.

    Certainly, there can be some value within an indoor environment, where there has been cases of transmission, to disinfect high-touch surfaces like a subway car. But, in general, I don't think that it's necessary to go out and start disinfecting the entire environment outdoors in the United States.

  • Amna Nawaz:

    Moving right along now to our next question, it comes to us from Liberty, Missouri. That's where we find Linda Armstrong. She reached out to us on Facebook and she sent us this video:

  • Linda Armstrong:

    What is the risk of swimming in a shared swimming pool?

  • Amna Nawaz:

    It's a very simple question, Angela.

    What do you say to her?

  • Angela Rasmussen:

    So, nobody has done any studies on SARS-Coronavirus-2 and how long it can persist in bodies of water, such as swimming pools, lakes, rivers, or the ocean.

    However, a group recently did analysis of other studies that had been published on other coronaviruses. And, in general, coronaviruses are fairly sensitive to chlorine and other oxidants that are put in swimming pools to disinfect them.

    So, at a pool, you're probably very unlikely to become infected by swimming in the actual pool. The biggest risk is going to be in crowds of people.

    So, one thing people should keep in mind is that viruses cannot reproduce on their own. They require a host to infect. So, you're always going to be at a higher risk of exposure to a virus when you're around other hosts.

    And for this virus, those other hosts are other people. So, if you're going to the pool or the beach in the summer, just make sure that you are practicing good physical distancing and avoiding crowds.

  • Amna Nawaz:

    All very good, useful information in this summer.

    Our last question comes to us from Gabriel Atchison. She's from Buffalo, New York. She reached out to us on our Web site, and she sent us this video:

  • Gabriel Atchison:

    I'm relying on deliveries of food and supplies in effort to stay home. How worried do we have to be about COVID-19 on cardboard boxes and plastic bags? Also, can the disease pass through food?

  • Amna Nawaz:

    Angela, so many people relying on those deliveries now.

    What do we know about transmission through the boxes and also through the food?

  • Angela Rasmussen:

    That's an excellent question.

    This has actually been studied for SARS-Coronavirus-2. And the virus can persist on cardboard for up to 24 hours. It can persist on plastic surfaces for up to three days, according to these experiments that were done under laboratory conditions.

    However, it's really important to note that, in these studies, after that period of time, while there was still infectious virus detectable, there were 1,000 times less virus particles than there were at the beginning of the experiment.

    And the good news about groceries and packages in general is that, if you wash your hands after you're handling these packages, the risk becomes even lower, to the point where it's probably minimal.

    As far as eating the virus and becoming infected with it by consuming food, we don't really have any information about that. But when you are eating, you're generally swallowing things.

    And those things go into your stomach, which is a very high — highly acidic environment. Most enveloped viruses, like coronaviruses, cannot survive and remain stable in that environment.

    Personally, I don't worry about contracting the virus from the food that I eat and the groceries that I prepare for meals for my family.

  • Amna Nawaz:

    Always good to know what someone, an expert in microbiology, is doing herself.

    Angela Rasmussen, thank you so much for taking the time to be with us today and taking these questions.

  • Angela Rasmussen:

    It's my pleasure. Thank you for having me, Amna.

  • Amna Nawaz:

    And thanks to all of you for your questions.

    You can send us more any time via "NewsHour"'s Twitter, Facebook and Instagram accounts or on our Web site. That's PBS.org/NewsHour.

  • Judy Woodruff:

    A lot of good advice.

    Thank you, Amna.

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