Fully Vaccinated Can Unmask Often, CDC Says

11:45 minutes

a white woman looking off screen taking off her mask
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This story is a part of Science Friday’s coverage on the novel coronavirus, the agent of the disease COVID-19. Listen to experts discuss the spread, outbreak response, and treatment.

As the number of vaccinated Americans continues to rise and evidence mounts that the vaccines may reduce viral transmission in addition to lessening disease severity, the CDC announced Thursday that fully-vaccinated people may be able to go mask-free except in specific crowded indoor situations. The announcement caused celebration in some circles and anxiety in others, with people wondering how the new guidelines fit into their personal risk assessments. 

Sarah Zhang, staff writer at The Atlantic, joins Ira to talk about the latest news in the pandemic and beyond, including a WHO committee report discussing the early days of the outbreak, the latest on the Colonial gas pipeline shutdown, research into cats’ love of sitting in boxes, and more. 

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Segment Guests

Sarah Zhang

Sarah Zhang is a staff writer at The Atlantic, based in Washington, D.C..

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, we’ll be talking about an AI algorithm studying pain and a story that may drive you to nuts. But first, last week we anticipated the impending green light for use of the Pfizer COVID vaccine in adolescents. That approval came through this week, and people aged 12 to 15 can now get the vaccine.

This week, the CDC changed its guidance on the coronavirus somewhat, officially acknowledging what many people have been taking for granted– the airborne nature of the virus’s spread. And the CDC said that fully vaccinated people might be able to go mask-free in many situations. In fact, CDC head Rochelle Walensky spoke at a White House briefing yesterday.

ROCHELLE WALENSKY: Anyone who is fully vaccinated can participate in indoor and outdoor activities, large or small, without wearing a mask or physical distancing. If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic.

IRA FLATOW: Here to talk about that and other short subjects in science is Sarah Zhang, staff writer for The Atlantic. Hi, Sarah.

SARAH ZHANG: Hi, Ira. Thanks for having me.

IRA FLATOW: So the big COVID news this week for many people is probably this guidance that masks might not be necessary for fully vaccinated people. Help us unpack that a bit.

SARAH ZHANG: So the CDC says that if you’re vaccinated, you don’t have to wear a mask indoors, though there are a couple exceptions. The couple exceptions are doctors’ offices and public transportation, because these are places where your risk of exposure might just be higher. From the biology itself, this makes a lot of sense. We know right now that if you are vaccinated, you’re very unlikely to get sick. If you do get sick, you’re very unlikely to get seriously sick.

So it is quite clear that if you’re vaccinated, the risk to yourself is just very, very low at this point. I think where the remaining questions are and where people might still have some hesitations is that a lot of parents, their kids might still not be vaccinated, or if they’re young, they might not be vaccinated for a long time. So I think one thing to think about this is the floor, right? Like, cities and local governments and even individual stores might still have mask guidances, and we’ll still have to follow those.

IRA FLATOW: I guess there might be a lot of trust involved here, because the challenge is that now you won’t know if someone is, in fact, vaccinated or just refusing to wear a mask.

SARAH ZHANG: Yeah, that’s right, and I think that’s what people who still have unvaccinated people in their lives are worried about. The risk is certainly not zero, just because even in very small cases you can be vaccinated and still perhaps get it asymptomatically. But it does still reduce the risks a lot, and of course if you’re still worried, feel free to keep wearing a mask.

IRA FLATOW: Of course. And in other COVID news, a committee of the World Health Organization issued a report on what went wrong last year in the early stages of a global response to the disease, and it called February 2020 “a lost month.” Tell us why that is.

SARAH ZHANG: Yeah, well if you remember back to February 2020, I think those of us in the US, we were seeing all these countries in Asia lock down, we had a lot of questions about, how are these going to affect our supply chains? And no one here was really thinking that much, oh, this is going to happen to us. So this report from– it’s a independent panel set up by the WHO to assess how we did, and looking back over the year, I think we can all agree that we could have done a lot better.

The panel has a bunch of specific recommendations for what the WHO could have done. But I think the big takeaway for me, the big conceptual takeaway, is the precautionary principle, which is that we should act even before we are perfectly certain of something. And so remember a year ago we had all these questions, is this virus spreading from person to person? Is it spreading asymptomatically? Is it airborne? And it took some time for the evidence to really accumulate 100%.

And so when you’re acting on a pandemic, you sometimes need to act before you know it’s 100%. Maybe it’s starting to look likely that it is asymptomatic. OK, we need to start making sure that people are wearing masks and shutting down, even before we’re 100% sure of that.

IRA FLATOW: Yeah, don’t assume anything. Take precautions in advance. In other news, let’s move on, it appears that the Colonial Pipeline has paid that ransom to get its pipeline back online.

SARAH ZHANG: (Laughs) Yes, that’s right.

IRA FLATOW: Is there a gas shortage, or is there not? It sort of seems it depends on where you live.

SARAH ZHANG: It does seem to depend on where you live. So the Colonial Pipeline carries about half the fuel on the East Coast. So it was shut down for about a week, I think they just turned it back on on Wednesday, so that did cause a bit of a supply crunch.

But the other thing that was happening is that people were hearing about the hack, people were going out and filling up their cars, and then there were lines at the gas station, then people were seeing, oh, there are lines at the gas station, those gas stations are running out, I have to go to the gas station. So suddenly you had this huge spike in demand as well. The problem was not that there was not enough gas on the East Coast, necessarily, but just that it was not in the right places where people wanted it at this moment.

IRA FLATOW: Yeah, because there were some photos of people filling up just about any plastic container they could get their hands on.

SARAH ZHANG: Yes, which you should not do.


IRA FLATOW: No. You know, did this not sort of remind you of the great toilet paper crisis from last March?

SARAH ZHANG: Yeah, yeah. In the same way is that it wasn’t like that there was necessarily a lack of toilet paper in the world, it was just about getting the right toilet paper to the right people who wanted it at this exact time. And suddenly everyone wanted it at the same time, and then you had a problem.

IRA FLATOW: Did they actually figure out what was behind this pipeline problem?

SARAH ZHANG: The pipeline itself was actually not hacked. What happened was that the company that runs the pipeline was hacked. It’s called a ransomware hack. They basically stole their data and said, unless you pay us this money, you can’t do anything. The reporting suggests that it actually took down their billing system. And of course, the company was worried that they weren’t able to run anything, so they just shut everything down for several days.

The ironic thing is that I think they actually paid the ransom, but unlocking their data took so long that it was faster for them to just go back and restore through their backups. (LAUGHS) It is a kind of ironic little twist there.

IRA FLATOW: Yeah, this sort of portends bad news for any other infrastructure.

SARAH ZHANG: Yeah, all of our electrical plants, these are all really vulnerable to hacks like this.

IRA FLATOW: Yeah, not only that, but our financial institutions, banks, maybe the stock market.

SARAH ZHANG: Yeah, these ransomware hacks have actually been happening usually to smaller institutions, but they’ve been happening at hospitals, local institutions, local city governments, and a lot of times if you’re a small– I think in this case, the government got involved, and Colonial Pipeline’s a pretty big company– but if you’re a small company, sometimes you just have to pay up, because that seems like the easiest way to deal with it.

IRA FLATOW: Yeah, like the hospitals. Let’s move on to other news. There’s important old seed news this week, old seeds.

SARAH ZHANG: Old seeds have sprouted. So the reason this is important is because this is actually part of a 140-year experiment to see how long seeds can last. So back in 1879, a botanist by the name of William James Beal had actually hidden thousands of seeds around Michigan. He literally buried them in a secret spot. And the idea is that he and his future colleagues every 20 years would go out and dig up these seeds under the cover of dark and then plant them and then see if they will still sprout. And so this latest excavation happened this past April, and some of these seeds have sprouted, about a dozen of them so far.

IRA FLATOW: Wow. What kinds of seeds are we talking about here?

SARAH ZHANG: Yeah, well, the funny thing is that it seems like all of the seeds that have sprouted all belong to one species, something called a moth mullein, which is like a flowering herb. The slightly bad news is that they are an invasive species. So now that we know that they can stay in the ground for 140 years and still germinate, that’s not great.

IRA FLATOW: No. No, well, that might explain why they’re so invasive, too.



IRA FLATOW: You have a story about an aquarium favorite, the betta fish, the Siamese fighting fish, those brightly colored fish kept in little round bowls. Tell us about that.

SARAH ZHANG: Yeah, so these fish were initially domesticated in Southeast Asia, where they’re native, as, as you said, fighting fish. They’re kind of like an aquatic version of cockfights that people like to watch and bet on. And so scientists are actually really interested in studying the genetics of aggression in these fish, because they’re easy to keep in the lab, especially compared to something like a bull or a chicken, that might be bred for aggression. A betta fish is a lot easier.

And so they went and looked at the DNA of these domesticated betta fish and actually found something unrelated that was surprising, which is that they have a sex gene that is not found in the same way in wild betta fish. So this might seem like, they have a sex gene, that’s pretty normal, but what’s unusual about fish is that the way they become male or female is just so varied and so diverse and far weirder than we think of as humans. Sometimes it’s based on temperature, sometimes if it’s all males one of the males will turn into a female, so we don’t really know what’s going on in wild betta fish. But in the process of breeding betta fish that are more beautiful, maybe better fighters, we seem to have also accidentally given them a sex gene.

IRA FLATOW: Wow. Who knew? I guess now we know, right?


SARAH ZHANG: Now we know. Yeah. No one set out looking for it, but there it was.

IRA FLATOW: So they don’t know what accounts for the sex in the wild betta fish?

SARAH ZHANG: No, it might be more than one factor. Sometimes breeders have talked about maybe temperature affecting whether it’s going to be a mostly female or mostly male brood. But it might be multifactorial. There are other– not betta fish, but there are other species of fish out there that have kind of similar chromosomes to humans, an XY, others have similar chromosomes to birds. Some have both at the same time. It’s just there are dozens and dozens of ways in which sex is determined in fish.

IRA FLATOW: Really interesting. Sticking with our potential pet theme this morning, there’s cat psychology news, the whole cats in boxes effect. Tell us about that.

SARAH ZHANG: Yeah, so we probably all know that cats love boxes and shopping bags and suitcases, and the theory is that these boxes just feel safe, they’re kind of swaddled and sheltered from everything else in the world. But what’s also interesting is that cats also love to sit on flat objects, 2D objects, like if I leave a sweater on my bed, my cat will always sit on the sweater, which is annoying because then sometime I want to wear the sweater. Or there are videos where if you take a scarf and you make a circle on the ground, the cat will go and sit inside that circle. Or even if you just tape a box on the ground, the cats would go and sit inside that box.

So the latest wrinkle to this is scientists actually did a study where, what happens if you don’t even have a box, you just have an illusion of a box? This is an optical illusion where you take a circle, cut out some wedges, and arrange them so it looks like there’s a box, but it’s not actually enclosed. And it seems like, even then, some cats will go sit in this illusory box. 500 cats participated, only 30 made it through, as you can imagine, being cats. But it does seem like that they’re fooled even by this optical illusion.

IRA FLATOW: Wow, so we’ve now given all our listeners something to do this weekend with their cats. Make that illusion.


IRA FLATOW: Thank you very much, Sarah.

SARAH ZHANG: Thank you.

IRA FLATOW: Sarah Zhang, staff writer for The Atlantic.

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