Coronapod: our future with an ever-present coronavirus

Benjamin Thompson

Welcome to Coronapod.

Noah Baker

In this show, we’re going to bring you Nature’s take on the latest COVID-19 developments.

Benjamin Thompson

And we’ll be speaking to experts around the world about research during the pandemic.

Amy Maxmen

We’re entering a new era now. We have new COVID strategies, there’s some new unknowns and we’ve got a vaccine.

Benjamin Thompson

Hi, listeners, Benjamin here coming to you from the South London basement. Once again, it’s time for another edition of Coronapod. Noah Baker is here of course, and joining us once more from Sydney, Australia is Nicky Phillips, Nature’s Asia-Pacific Bureau Chief. Hello to you both.

Nicky Phillips

Hello.

Noah Baker

Hi, Ben. Hi, Nicky.

Benjamin Thompson

Well, Nicky, we’ve not had you on the show for a while. I guess before we start talking about today’s subject, it might be worth just checking in. What’s going on with coronavirus in Australia?

Nicky Phillips

Well, I have to say, Ben, that actually things are looking pretty good in Australia. I guess we’re feeling very lucky here. I’m in the city of Sydney and I think we are about 30 days, maybe even 32 days, without a single case of local transmission, so a pretty enviable position, I would say, and really most of Australia is in that position, so we’ve managed to keep the virus very much under control here.

Noah Baker

Yeah, I remember when I last spoke to Smriti Mallapaty, one of our colleagues who’s also in Australia, and she said the same thing with this kind of like, ‘Sorry guys, but we’re in kind of an okay position.’ But then she did point out that the reason for that is really quite severe travel restrictions, so you can’t really get out of Australia or into Australia very easily right now.

Nicky Phillips

Yeah, that is the sacrifice we are making.

Benjamin Thompson

Well, today we’re going to be doing a bit of future gazing towards what the end of the pandemic might look like, and that’s something you’ve been investigating for Nature this week, Nicky. Now, there are obviously a lot of versions of what might happen, and you’ve actually gone out to speak to some experts to find out which they think is most likely.

Nicky Phillips

Yeah, so, I guess we were trying to look into the future a little bit and see where might this pandemic end and how might it end, so I did a survey with my colleagues here at Nature where we asked a bunch of people who’ve been working on the coronavirus whether or not they think this virus can ever be eradicated, and I guess the depressing answer to that was ‘No, we don’t think it can be eradicated,’ and I guess that’s partly because the virus has spread so far and is just across the globe everywhere. So, the consensus from about 100 experts, we’re talking virologists, epidemiologists, infectious disease experts, was that it’s very unlikely that we’ll be able to eradicate this virus. And so, what that means is that the virus becomes something we call ‘endemic’.

Noah Baker

‘Endemic’ is a word that we’re going to use a lot in this chat in Coronapod. I wonder if you can just give me a one-line definition of what ‘endemic’ means, Nicky?

Nicky Phillips

So, ‘endemic’ means that a virus continues to circulate in regions around the world. So, an example of an endemic virus is something like the flu which continues to circulate in people.

Noah Baker

Yeah, and I think, importantly, like the flu, although it can still cause illness and severe illness and can kill people, this is not the same as what we’re experiencing right now where there is a virus that’s transmitted around the world and we’re having to respond with quite extreme measures such as social distancing, isolation, travel bans and so on.

Nicky Phillips

Yeah, exactly. I mean, once a virus is endemic then there is usually an expected number of infections that we kind of are used to. At the moment, we’re in the pandemic phase of this virus which means that there’s still a lot of people who’ve never been exposed, who don’t have any immunity, so the number of infections is just rising and rising and rising.

Noah Baker

I have to say, way back at the beginning of the pandemic, in fact, before it had even been declared a pandemic when we published our first video about the virus which is called ‘Five things you need to know about the novel coronavirus’, one of those big things that scientists wanted to know was, ‘Will this virus become endemic?’ And now we really are faced with that question front and centre as we think about what the end game is of all of these various restrictions. People want to get out of them. How are they going to get out of them and what might that look like?

Nicky Phillips

Yeah, I think you’re right, Noah, and I think for a long time, scientists were pretty cautious about making a kind of statement either way, whether they thought it would or wouldn’t, just because there wasn’t enough evidence. But I feel like now that the virus has spread so far, and there are other aspects of the virus that we now know more about because people have been studying it for the past year, about whether people become immune to it and how long that immunity lasts. We’ve got vaccines now and so we’re getting some sense of whether vaccines just prevent people from getting severe disease or can it prevent people from being infectious and passing on the virus. Now that we know a little bit more about these things – I mean, there’s still a lot to learn, don’t get me wrong – I think scientists do feel more comfortable saying that, ‘Yes, we think it’s unlikely this virus can be eradicated.’ I mean, I should say, that makes it sound quite ominous and scary. I mean, no one really wants to really live another 2020. But I should say that just because a virus becomes endemic doesn’t mean that we are facing a future with the number of deaths and social isolation and devastation that we’ve had over the last 12 months. I mean, the scale of those things I don’t think needs to be our future, even if this virus does become endemic. We do have some control over how things pan out.

Noah Baker

One of the overarching things that I’m sort of feeling, Nicky, as you’re talking is, ‘God, this is complicated,’ as I think we have been feeling for much of this pandemic. If people are interested, you’ve written a fabulous feature that’s been published in Nature just a couple of days ago, and there is a flowchart in there that actually helps sort of make sense of all of these different possible outcomes. But I’m interested in kind of what are the kind of options we’re facing in the future, based on all of these different competing factors. What are the options, I suppose, with the pandemic?

Nicky Phillips

Yeah, sure. I mean, so, I guess one scenario is that the virus could be eradicated. As we’ve talked about today, that seems pretty unlikely and that’s the opinion of most scientists. Next option is that it could be eliminated in regions around the world, and this could be a little bit like we’ve eliminated measles from lots of countries around the world. So, that’s one scenario that we could see for SARS-CoV-2 as well. Another scenario is that the virus will continue to circulate, but once people have some immune protection either because they’ve been infected with the virus or they’ve got a vaccine then it could become a little bit like the other what we call ‘endemic coronaviruses’. There are these four endemic coronaviruses that circulate the globe that you and I and everyone has almost certainly come in contact with. They are the types of viruses that cause the common cold, the sniffles that your kids get, and they really don’t cause severe disease. I mean, the flipside of that is that the virus could continue to circulate and even though most people have some immunity, that is not enough to protect against severe illness, and I think in that scenario we would see that SARS-CoV-2 continues to be a burden on society for a long time and might require other interventions like the ones we’ve been living with for the last 12 months. And I guess another kind of iteration of that scenario is that the virus circulates seasonally a bit like flu.

Noah Baker

Yeah, I guess when you think about this, people often hark back to the 1918 flu pandemic, and that is an example of a virus that did eventually become endemic, and that was a very, very severe pandemic. Many, many millions of people died and now the seasonal flus kill something like 650,000 people a year, which is still pretty significant and not great, but scientists don’t think that coronavirus is going down that route. I mean, perhaps that might happen, but not with that kind of devastating impact.

Nicky Phillips

No, I don’t think so. I mean, influenza viruses are quite different from coronaviruses, so that’s sort of one factor to keep in mind. We’ve had a number of flu pandemics in the last 100 years. I mean, 1918 was particularly bad. And what happens is these are new viruses that the population is completely naïve to, so they are always going to have their kind of strongest, most devastating effect on a naïve population. But over time, these flu viruses continue to circulate and come into contact with more and more people who have immunity and so then they just kind of develop this seasonal pattern. But I mean, one thing to point out with flu viruses is that they evolve really quickly, which is the reason why you have to have a flu vaccine every year is because the virus itself is very good at outmanoeuvring our immune system. That might not be the case with coronavirus. We’ve got these great vaccines for the coronavirus which are really effective at preventing serious disease and death. So, there’s potential – we don’t know yet – that these vaccines will need to be remade, particularly as new variants of the coronavirus emerge and circulate, but it’s far from clear that these vaccines will need to be updated yearly like the flu.

Noah Baker

And I guess one of the goals of vaccine drives like we’re part of in kind of a really unprecedentedly global scale right now is to try to move towards a place where herd immunity exists, where there’s enough protection within a population from people that have been either exposed naturally to the virus or have had access to the vaccine, that the transmission rates slow and can even be halted completely, as has happened with something like measles, for example. Is that something that looks like it’s likely in the context of SARS-CoV-2?

Nicky Phillips

Yeah, that scenario very much depends on how well the vaccines perform at not just preventing disease but at preventing infectiousness. So, the idea that someone who has been vaccinated, if they got the infection, they can’t pass it on to people. Because herd immunity is all about having enough people immune that they offer some indirect protection to the people who don’t have immunity. The reason that can happen with measles is because the measles vaccine is really, really effective. It was made in the 1960s and it’s never needed to be reformulated. You have two doses when you’re a kid and that gives most people protection for life. So, because it’s such an effective vaccine, as long as enough people in a given community are given that vaccine then the effect of herd immunity can keep measles out of that community. What happens if there’s not enough people vaccinated then outbreaks can happen. So, whether or not we’re looking at that kind of scenario for SARS-CoV-2 will depend on how well the vaccines block transmission of the virus. And there are some early data that suggests that the vaccines can possibly block transmission. I mean, we’ve got these new variants that are coming up that might affect that, but I think it’s still very much yet to be seen, really. And so, when you have a vaccine that is really effective, say 90% effective, at blocking transmission, then you don’t need to have as many people in the community vaccinated. But if a vaccine is less than 90% effective then that means you have to vaccinate more people, so it’s sort of a bit of a balancing act and in some places, vaccinating 50% of people might be really difficult for a combination of reasons. We’ve seen with this pandemic a rise in vaccine hesitancy but also there is a lot of countries that just don’t have the infrastructure to distribute that many vaccines to make sure enough people get vaccinated to create that herd immunity effect.

Benjamin Thompson

Crystal ball gazing is always a bit tricky, Nicky, but it does seem from you feature article that another important aspect as to what scenario we end up going down is what does the immune system do and how long does it do it for, and that’s something that’s being looked at right now.

Nicky Phillips

In terms of this idea that your immunity could wane, at the end of last year we started to see studies that looked at immunity in people who had been infected with SARS-CoV-2, and how that immune memory had lasted over a period of time. And so, there was one study that was done by a group in the US that looked at people’s immune memory 6-8 months after they’d been infected, and what they found was that a lot of people had neutralising antibodies, which are these antibodies that sort of block reinfection, so they’re really important. So, lots of people had neutralising antibodies. They did sort of drop off from about 6-8 months, and that really worried people. There was a lot of press at the time. But this study that was done mostly by researchers in the US said, ‘Yes, that seems to be the case but actually we also found that lots of people who’ve had COVID also have really healthy amounts of these things called memory B cells and T cells.’ And memory B cells are what make antibodies and then once a virus is inside a cell it’s the T cells that kind of attack those cells. So, what you could take away from that study was quite positive, really. It suggested that people do have immune memory and that it lasts a long time. Now, whether or not it lasts 1 year, 2 years, 3 years or 5 years, we don’t know, but that’s what people are tracking now to see how long this immune memory lasts and how protective it is against reinfection.

Noah Baker

Okay, so if I put my rose-tinted goggles on, which I put on all the time now just to look at my living room to make myself feel better, and we imagine that immunity doesn’t wane over time and that the virus doesn’t evolve to escape the immune system and that people around the world are vaccinated in a relatively systematic way without holes, there is still one stumbling block and that is the possibility that the virus could have one final refuge in animals.

Nicky Phillips

Yeah, that scenario that you painted just before sounds a lot like measles, but what would make it quite different is if the virus was able to find a refuge in an animal population. A lot of scientists didn’t think this was a hugely likely scenario, but we can’t rule it out because SARS-CoV-2 can infect a lot of animals, from minks to cats to tigers. It really can survive in a lot of different species. What we haven’t seen is circulation of the virus in a wild population, which would really worry scientists because it would be a reservoir that could lead to potential future spill over events. So, we haven’t seen that so far, and maybe that’s a good thing because it means maybe it’s unlikely, but with other viruses that have a reservoir in animals, it can be really difficult to eradicate or eliminate those viruses because there’s this constant threat of a spill over back in to people.

Benjamin Thompson

Well, Nicky, you’ve laid out a bunch of potential scenarios then. Is it possible to know when one becomes more likely than the other?

Nicky Phillips

That’s a really good question. I’d be speculating because this isn’t a question I asked people, but I would imagine when we know if vaccines are effective at blocking transmission then that suggests that maybe it might be possible to eliminate the virus from various regions and we might be ending up sort of like at a measles scenario. And conversely, if in the next 6-12 months we see evidence that immunity does wane kind of as quickly as, say maybe flu, then that might suggest that that path is more likely. But I would say that – I sound like a scientist now – there’s a lot of research to be done to really know.

Noah Baker

I do really like that in all of our surveys one of the options was ‘not enough evidence to estimate’, which were small but still quite significant answers for the people that you polled.

Nicky Phillips

I was surprised that not as many people used that option. I thought a lot more people would select that than did. So, scientists are usually a fairly cautious bunch and the fact that a lot of them felt there was enough evidence to suggest that it would be difficult to eradicate the virus and so this will become endemic, I found, yeah, interesting.

Benjamin Thompson

Well, let’s leave it there for this week. I’ll put a link to your feature in the show notes, Nicky, so listeners can find out more about the potential futures for the pandemic, and I hope you’ll join us again when more data does become available. But in the meantime, Nicky and Noah, thank you so much for joining me.

Nicky Phillips

Great to be with you.

Noah Baker

Thanks, Nicky. Thanks, Ben.