On Friday, the Centers for Disease Control and Prevention recommended that Americans wear face coverings when venturing out in public. The new guidelines come a month after the surgeon general urged people to stop buying masks, tweeting that they are “NOT effective” in preventing the general public from contracting COVID-19. So, what exactly should people wear now and when should they wear them?

On this episode of the podcast Social Distance, James Hamblin answers Katherine Wells’s basic questions about the coronavirus. What is a virus? Why is this one so bad? And what should be done to avoid catching it?

Listen to the episode here:

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What follows is an edited and condensed transcript of their conversation.

Katherine Wells: What even is a virus?

James Hamblin: It's just a strand of nucleic acids, DNA or RNA, wrapped in some little coating or shell or capsule that can keep it alive for a small period of time.

Wells: Are viruses like early life forms?

Hamblin: This is a fundamental question of biology and beyond even: “Is a virus alive?” It depends on how you define alive. A virus requires a living being in order to reproduce. It cannot reproduce on its own. But in much subtler ways, most living things require other living things in order to continue living. Human beings can't reproduce on their own, if you take one human being and leave them in the middle of nowhere. So, there are kind of existential questions about where you draw that line of what defines life.

Wells: What's the evolutionary incentive of a virus? If it could, it would just kill everything and be everywhere?

Hamblin: I might think of it more like a tide when you take down a dam. It's not like the water wants anything. If there's a town below that dam, the water doesn't want to destroy anything. It doesn't even have an evolutionary instinct. It's just a physical force. It's just, this is what it does. It finds that receptor and invades the cell and makes more.

Wells: Is it adaptive for the virus to kill us?

Hamblin: That's part of what caused me initially to raise these alarm bells and get really concerned myself in February, is the basic science of it. I initially wrote this story, “You’re Likely to Get the Coronavirus,”  and it made the point that there are a lot of mild cases out there—mild in terms of COVID-19, which is not a mild disease—and that there are asymptomatic carriers. There’s a long period of incubation when you can be asymptomatic. And that is what’s so scary about it.

Wells: Like, if it was a worse disease, it wouldn’t be so dangerous?

Hamblin: Let’s talk about it as if it were a human. There are some people who are just really genuine and good and you want to be around them and work with them and have them be in your life. And there are people who are clearly malicious and terrible, and you can immediately tell, like: Get that person away from me. And even though you might think, Oh that person is straight up dangerous; they immediately threatened to kill me, the actual probably most dangerous person is the one who is what we’d call a psychopath. Someone who seems intuitive and smart and thoughtful and caring, but actually has all these devious plans and is actually able to carry them out because they aren’t out there threatening people and throwing off signals that they’re a dangerous person. That’s what this virus is, and that’s why people fell along a spectrum of how scared they were by this. Some people were like: “Oh, it looks like these other coronaviruses, where it causes a lot of mild cases where people don’t die, so it’s not that dangerous.” And other people were like: “No, it’s because it’s so good at spreading and doesn’t kill everyone that it is so dangerous.”

Wells: To the extent that I’m going to get what the virus is, I get it. But one of the things that’s been sort of paralyzing recently is, I don’t know where it is. If I walk outside, is it in the air? Is it on surfaces?

Hamblin: The main way that people get it is from touching things and then touching their face. That continues to be the main way. That’s why hand-washing is so important. That’s why not touching your face is so important.

The two types of viral transmission that we’ve long thought about are droplets or airborne, as in: Is it just in these gooey little drops that come out when you sneeze or cough? Some of them are tiny, and they might fly up to six feet, but ultimately, they’re going to fall down and hit the ground, versus: Do you mist this out and does it just hang in the air like oxygen or carbon dioxide and then sort of dissipates?

It turns out there’s not a black-and-white line between those two things. That dichotomy was false. This one appears to be almost entirely droplets. Occasionally, you can detect some lingering in the air for longer periods, but not clearly enough that it could infect someone unless someone is very sick, coughing and sneezing, and you were in close contact with them in a place with no airflow. So, you could be more than six feet away, but say we’re sharing a cruise-ship cabin and I'm just coughing and sneezing stuff into the air. It’s shooting out, and you're on the bed eight feet away, but we’re constantly just using the same air. There is a possibility that could happen.

Wells: So, it’s not impossible that I could walk outside and just breathe it in accidentally, even though there’s no one around?

Hamblin: No, that’s impossible. I want to say that’s impossible. I don’t think anyone should be worrying at that level, because we have to be able to say we can move about the world, not in states of constant fear. And walking is important, especially if we’re going to need to be doing this distancing stuff for a year. If people feel like they can’t go outside and can’t move their bodies, we are going to see compounding of all sorts of other health issues and worsening cases of this disease, because if you are worn down and not exercising and not sleeping and depressed and not eating well, you’re not priming yourself to be in good condition when you do get sick.

Wells: So as far as we understand, it's really: the gooey drops is the problem. Even if they're tiny, they fall to the floor quickly once they're expelled from someone's body. So, it really is getting close to other people and surfaces that are the problem. It's not just, like, the air.

Hamblin: The only instances where we believe the air would be a problem is in a constant exposure. And it would have to be a long-term thing. If you briefly shared an elevator with someone who didn’t even sneeze or cough and you were as far away from that person as you could be in an elevator, there is as close to zero percent chance of anything happening in that situation as possible.

Wells: Okay. So I don’t need to be terrified of going outside and of other people. That blanket terror is not rational. In what situations am I supposed to wear a mask, and what constitutes a “mask,” given that I don't actually have a mask?

Hamblin: Right, we should define “mask.” When you say “mask,” what do you think of?

Wells: Well, I understand there's the N95. I understand there's the surgical mask. And then I understand there's what I did this morning, which is take a scarf and loop it three times around my face, which I wouldn't call a mask, but it is an attempt at some sort of barrier.

Hamblin: So, a respirator is also sometimes referred to as a mask or an N95 mask. Those are these tightly woven things which are rigid and they look like a dog's snout and they are supposed to seal perfectly around your face. These are pretty much medical devices, not something you would wear all day, every day. That's what we definitely have a shortage of. We've exhausted our national strategic stockpile as of this week, which was supposed to last us for a long time. Those are so crucial for people who have to get up real close to someone who is coughing and sneezing. But you don't need that level of seal unless you are close to someone who is coughing and sneezing.

Wells: OK, so the N95 thing. I don't have an N95, I assume I couldn't get one if I tried. The doctors need them anyway. We're not talking about it N95s for the average person.

Hamblin: No. Apart from very specific cases. And this is going to be on everyone’s mind because the CDC is now telling people: Cover your face with something. If you’re sick, if you’re coughing and sneezing, just do not go out. When you are feeling okay and you need to go out, the recommendation now is that you wear something to cover your mouth. If you were practicing appropriate social distancing, that would be of no use, no value.

Wells: But it's very difficult. In New York City, when you're going into a store, even with all of these measures, it's not really possible to always stay six feet from other people.

Hamblin: Right. It's not clear to me what the utility of covering your face is if you are not coughing and sneezing, you're totally asymptomatic and you're not getting into a confined space for prolonged periods with someone else. The actual value of wearing a handkerchief over your mouth is not clear to me.

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