KATHLEEN DAVIS: This is Science Friday. I’m Kathleen Davis.

IRA FLATOW: And I’m Ira Flatow. I want to get personal for a moment because last week, guess what? Maybe you can hear it in my throat. I got COVID-19 for the first time. It’s a very mild case. Thank you. Very low fever I had. I finished my last dosage of Paxlovid on Tuesday. So please excuse my voice. It comes with the illness. It was a bit of an eye-opening experience.

It was a reminder that despite a lot of people acting like they were before COVID-19, well, it is still out there. And I’m beginning to mask up again. Statistics say COVID is on the rise, this new wave. So what’s better than talking about the latest thinking on the vaccines and the disease’s evolution?

And to do that, I want to welcome back our long-time expert, Dr. Angela Rasmussen, virologist at VIDO, the Vaccine and Infectious Disease Organization, University of Saskatchewan. That’s in Saskatoon, Canada. I love to say that name. Welcome back.

ANGELA RASMUSSEN: Thanks so much for having me back, Ira. And I’m sorry about the circumstances.

IRA FLATOW: What’s the deal? Is there an outbreak, a new outbreak of it? Is there a new variant going around? Because I have seen so many people getting it now.

ANGELA RASMUSSEN: So I wouldn’t call it a new outbreak. In many ways, the outbreak has been going on since 2020 when it first emerged. But there certainly is a rise in cases compared to what we had several months before. There are also new variants around or, really, more accurately, they’re subvariants all derived from the omicron family.

So we’ve been dealing essentially with the same variants of concern since late 2021. However, there is a new omicron subvariant in town as well as several others that have been spreading for the last six to nine months or so.

IRA FLATOW: Now I need a little bit of advice about getting tested because I’m testing myself just about every day. And I have seen conflicting advice in how often you get tested after you get positive results the first time.

Some people are saying keep testing until you’re twice negative. On the other extreme, I’ve heard doctors say no need to keep testing, as you will keep testing positive for a while. And you can go out after you tested positive after five days. What’s the thinking? What is the thinking here now?

ANGELA RASMUSSEN: Yeah, so this is something that has been perpetually very, very confusing for people. And I think a lot of it stems from the CDC’s guidance, which now says that you are supposed to wait and isolate for five days after you test positive. But then you can go ahead, essentially, and go back to your usual life, although certainly it’s safer for other people if you do wait until you test negative. And there’s all sorts of rules and guidelines for different scenarios.

If you still have symptoms after five days, and the symptoms haven’t gotten better, then maybe you should consider isolating for a longer period of time. But what do people really need to know? I mean, I think there’s a lot of confusion here because the tests themselves, the rapid antigen tests, don’t necessarily prove that you are infectious, that you’re shedding actually infectious virus. What those tests look for is the nucleocapsid protein of SARS-2, which is a major component of the virus particle.

So if you have a positive test, that means you’re shedding a lot of N protein from your nose. A lot of people assume that that means that you’re also shedding infectious virus, and that would be my assumption as well. But there’s not a lot of numbers that clearly correlate when a person actually stops being contagious with a potential to infect other people.

Now to be really, really sure, you can, of course, test two days in a row or have two negative tests within 48 hours of each other. Then you’re pretty sure that it’s not going to come back, and you’re not going to test positive. But at the same time, I would say that it’s best and safest for everybody else around you to go ahead and wait until you do test negative at least once.

IRA FLATOW: OK, a question from Sam on Threads, who asks, how prepared are we for new waves or variants now that the government subsidies for free tests are gone? And boy, did I notice that? It’s $10 or $20, a two-pack of tests. The free tests are gone, although the Paxlovid is free.

ANGELA RASMUSSEN: Yeah, this is another big issue, I think. And this may be part of the reason that the CDC continues to be somewhat unclear on their guidance or have at least multiple scenarios that you can kind of follow because certainly not everybody’s going to be able to afford to test constantly, with the test costing so much and no free testing available. Without question, the loss of resources in general, tests and even tracking in many public health departments in many communities.

There’s no funding for that anymore. And so that money did come from somewhere. It doesn’t exist anymore, and it does make us less prepared and less capable of responding to increases in cases. So this is a problem in many places, including the US. And I don’t see it, unfortunately, getting any better. I don’t think that there’s going to be, all of a sudden, more money to provide resources to people. And so, unfortunately, that means that a lot of us just have to do the best we can.

IRA FLATOW: Because the assumption that we’ve been told recently is, well, COVID is now benign enough to be just as bad as any other kind of respiratory infection, the flu or something like that, unless you get it, and you’re a long hauler, right?

ANGELA RASMUSSEN: That’s absolutely right. And I think for many people, the same thing is true with seasonal influenza. For many people, it can be a manageable disease. But for many other people, it’s not. People who are at high risk of getting COVID, people who are immunosuppressed, people who are elderly, people who have other comorbidities can’t necessarily expect it to be a walk in the park.

Now vaccines do work reliably at protecting against severe disease, but they don’t protect everybody. So if there’s a lot of cases in the community, even if the overall proportion is low, there will still be a percentage of people who are going to get very sick from COVID-19 because they are higher risk. And there will be a percentage of people who end up with long COVID.

And to me, I think that it’s generally a bad idea to dismiss anything that is a persistent public health problem, which COVID-19 is. Just because it’s not an emergency anymore doesn’t mean that it’s not still a problem and doesn’t mean that it’s not something we should still take seriously and try to avoid.

IRA FLATOW: All right. You mentioned vaccines. Let’s talk about vaccines. There’s a new monovalent booster coming out.

ANGELA RASMUSSEN: There is, yes. So because omicron has been with us for the last almost two years, people have been discussing changing and updating the vaccine. So previously, about almost a year ago now, we started looking at bivalent vaccines.

So the bivalent vaccines were vaccine boosters that included one dose of the old-fashioned original recipe SARS-coronavirus-2 that was in the original vaccines as well as a bivalent second dose, essentially, of BA.5, which was the omicron subvariant that was circulating primarily in the US at the time. And so people were getting that.

And that definitely does improve immunity, especially short-term immunity, to BA.5. But that immunity is somewhat short term. After a while, the antibodies that those booster shots elicit will go back down. You will still have the same protection against severe disease that all of the COVID shots have provided, but you won’t necessarily have as good of protection against getting infected.

And obviously, that’s something that a lot of people would like to avoid. So the vaccines have now been reformulated again to provide these updated boosters, which are going to be specific for XBB.1.5, which is a variant that was up until very recently the dominant variant.

Now all of the variants that are circulating, for the most part, the majority of them are derived from the XBB family. And we can talk about that in a moment, but that’s the reasoning behind updating that booster. It’s to make it a little bit more specific for the viruses that are currently circulating now.

IRA FLATOW: Because I had heard a while back that they were going to combine the seasonal flu shot, right, with this new booster. But that’s not going to happen?

ANGELA RASMUSSEN: I don’t think that’s going to happen, at least not this year. The seasonal flu shot will be, just like in previous years, using the existing sort of flu shot technology, which is older vaccine technology. I think you can still probably get the flu shot at the same time as you get the SARS-2 booster, but they won’t be combined into one vaccine.

IRA FLATOW: OK, now I’m just getting over COVID now. For everybody who’s getting over it, do I have to wait a certain time to get that new vaccine?

ANGELA RASMUSSEN: So previously, you were asked to wait for a period of at least four weeks. And usually, sometimes it would be more. So 8 to 12 weeks, perhaps, after you’ve recovered from COVID or had a recent booster. And that varies depending on where you are and which boosters will be available for you. But yes, in general, you do want to wait after you get a booster or you recover from COVID to get another one.

The reason for this is that your immune system will respond to an infection or a booster shot. And that response can actually be fairly drawn out. It takes a while for the immune system to essentially internalize all the lessons that it just learned from that exposure and to go back to effectively a quiescent state, where it’s ready to learn about the next new thing that it has to develop immunity against.

IRA FLATOW: Yeah, we want that. OK, listener [? Kathy ?] asks, why is the CDC saying yearly vaccines, like flu shots, when the vaccines are only good for six months, and we get surges in the summer talking about the COVID vaccine?

ANGELA RASMUSSEN: Yeah, that’s a great question. And part of this has to do with the fact that we’ve been dealing with influenza, seasonal influenza, for a really long time, for decades. That seasonality is completely well understood. It is not as well understood for SARS-coronavirus-2.

Now I think it’s probably safe to say that we can expect to see surges in SARS-2 cases or COVID cases in the fall and winter during cold and flu season for the same reason that we see a lot of respiratory viruses surge during that time. The weather gets colder. People start spending more time indoors. People are engaging in behavior, like family gatherings around the holidays, things like that that put them at higher risk for COVID.

So I think that it’s reasonable to expect that we will be experiencing this for winters to come. With a summer, it’s a little bit trickier because there have been these summer surges or at least increases in cases. This year is no exception, although this increase in cases is smaller than it has been in previous years.

So it’s unclear, I think, really over the long term whether this is something that we’re going to be dealing with in every year and in every location because some of this might also be reflective of people’s behavior and the environment. So for example, we’ve had terrible heat waves in many parts of the country, many parts of North America. And when that happens, people also spend a lot of time indoors together. So I think that some of it has to do with that. But the other thing is is that there is a point of diminishing returns.

The demand for boosters has continually gone down. Asking people to go back and get boosters twice a year, for many people, can be an issue of access. And it can actually be kind of a heavy lift for people, especially when the boosters themselves and these vaccines are not completely protective against infection, which is also the case for seasonal influenza. I mean, the flu shot does not prevent every influenza infection.

But like the SARS-CoV-2 shots, they do protect against more severe disease. They can make it a lot less severe, and they can keep you out of the hospital and keep you out of the morgue.

And I think that is really the focus with the COVID vaccines is now to make it an annual thing, which is I think a lot easier for people to do. It’s less of an ask for people. And it can be combined with a visit to get your seasonal flu shot. And it will provide that protection against severe disease for the entire year.

IRA FLATOW: This is Science Friday from WNYC Studios. This question about getting vaccinated again raises an interesting point that [? Cavett ?] on Twitter asks and saying, we eliminated smallpox. Why can’t we eliminate COVID?

ANGELA RASMUSSEN: That’s a great question. And there’s a couple answers, and not all of them actually have to do with vaccines. So smallpox eradication was incredibly effective for a couple reasons. One, the vaccine completely protects against actually contracting variola virus, which causes smallpox.

And obviously, the COVID vaccines are very good at protecting against the disease that SARS-coronavirus-2 causes, but they don’t completely protect against getting infected with the virus. So that’s one problem. But another problem has to do with the different types of hosts that the viruses can infect. So variola virus smallpox was very specialized to only infect humans.

And it largely circulated only within the human population. SARS-coronavirus-2 is a much less picky virus about what its host can be. So we already know that SARS-coronavirus-2 can infect cats, dogs, actually all types of cats. So many big cats in zoos have been infected as well. So tigers, lions, panthers, cougars, things like that.

We know white-tailed deer have been infected, and wild white-tailed deer are transmitting variants that are no longer even present in the human population amongst each other. We know that many minks and other species of carnivores, including things that are farmed, which is how the mink infections were discovered, can get it. And they can pass it to each other. They can also pass it back to humans. So there’s a lot of different potential hosts for SARS-coronavirus-2.

And when SARS-coronavirus-2 or any virus really gets into an animal population after it’s been into the human population, and it can be sustained in those animals, that means that it’s going to be a lot more difficult to eradicate because there are going to be animals, especially since many of these animals are wild, that we can’t vaccinate. We can’t track down every single white-tailed deer in North America and give it a COVID shot, much less a booster.

So unfortunately, we are stuck with SARS-coronavirus-2 circulating in the human population, in our animal populations, for the foreseeable future. It’s really important, I think, if we ever do want to eliminate it, which is a little different than eradication. That just means that it’s not actively spreading through the population, but it’s still out there.

If we wanted to eliminate it, I think we are going to have to develop better vaccines that can produce more sterilizing immunity, so immunity that doesn’t allow infection at all. And that will be one way that we will be able to potentially eliminate it and not have to worry about it so much. But it’s very challenging to do that for respiratory viruses. And I’m happy to chat about that a little more, if you’re interested.

IRA FLATOW: Yes, we’ll get into it next time because we’ve run out of time. This has just been terrific, Angela.

ANGELA RASMUSSEN: It’s wonderful being here, Ira. And as much as I’m tired of talking about COVID, it’s always a pleasure to come talk to you about it.

IRA FLATOW: [LAUGHS] Well, thank you very much, Dr. Angela Rasmussen, virologist at VIDO, the Vaccine and Infectious Disease Organization. That’s at the University of Saskatchewan in Saskatoon, Canada.

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