Flu vaccines - advancements, challenges, and global impact

Aida Bakri: 0:00

Welcome to ESWI Airborne and our special series on intervention strategies for diseases caused by acute respiratory viruses. This episode on intervention strategies for influenza is made possible thanks to the kind support of our sponsors Moderna and Viatris.

Claire Taylor: 0:12

You are listening to the podcast of the European Scientific Working group on Influenza, also known as ESWI. This is where we talk with the scientists and clinicians who know the most about viruses, the risks, prevention and cutting edge scientific developments. I'm your host, Claire Taylor. Today we're talking all about influenza in relation to vaccine production platforms. We're talking about flu in today's episode, but it's really important to remember that for the majority of viral diseases, like the ongoing HIV pandemic, we have no vaccine yet, which really underlines the importance of ongoing developments in vaccine production technology. The topic of today's episode, and here with me in the studio, is ESWI Luminary Professor Albert Osterhaus, member of the ESWI board since its inception and director of the Centre of Infection Medicine and Zoonosis Research at the University of Veterinary Medicine in Hanover, Germany. Welcome, Ab,

Albert Osterhaus: 1:38

Thank you.

And next up, I am always delighted to see Florian Kramer, Renaissance man and professor of vaccinology at the Department of Microbiology at the Icahn School of Medicine at Mount Sinai in New York and professor for infection biology at the Medical University of Vienna. Always great to see you, Florian

Florian Kramer: 2:00

Good to see you.

And finally, Caroline van der Sant, senior Research Fellow Department of Microbiology and Immunology at the Peter Doherty Institute in Australia. Our listeners may remember Caroline from the Life as a Scientist series, very happy to see that Caroline has been shortlisted for this year's Nature Inspiring Women in Science Awards. Congratulations, Caroline. This is really fantastic recognition of your work.

Caroline van der Sant: 2:27

Thank you.

Well, don't be shy, everyone. Let's get started. We're talking about vaccine production platforms. So in a nutshell, right, I understand that these are technologies that make it possible for multiple vaccines to be more rapidly produced from a single system. And how long have vaccine platform technologies been around, Alb? Maybe you can get us started.

Yeah, that's not an easy question to answer, but I think if you go back at the origin of virology, really, people managed to propagate viruses in animals and later in eggs. And then, when we're talking about platforms, when you can propagate a virus in eggs, in embryonated chicken eggs, you can also use that virus to make a vaccine, and these were the first primitive vaccines that were being made by our ancestors, our grandparents, so to say. And gradually, new platforms have come about and I think it's important still to realize that it's more than 40, 50 years already, even more, 60, 70, perhaps that we have vaccines that have been produced in that particular today we would say primitive platform, but that's still being used today for the majority of the vaccines.

Florian, do you want to enlighten us here? Since when has this sort of platform technology been a bit of a buzz phrase?

Abis is absolutely right. We have different vaccine production platforms for a long time. But I think the modern use of platform technology is more or less technologies to produce vaccines where we can switch very quickly between antigens, even between viruses that we target Right, and so what we kind of. When we talk about production or vaccine platforms, we typically now talk about mRNA vaccines, vector vaccines, some recombinant vaccine production platforms make the vaccines some recombinant vaccine production platforms. So those are platforms where you can really switch from one antigen to another very quickly and respond very quickly to an ongoing or emerging problem.

Okay, so what can you say broadly about the advantages and disadvantages? I mean, I understand from what you've just said that we are talking about a range of platforms here and each will have pros and cons. What can you tell us about the advantages of some of the platforms, perhaps?

In general, these platform technologies have the advantage that you don't have to change the production process very much. Right, Specifically for mRNA vaccines or even DNA vaccines. You just basically use a new sequence that you want to code for your new antigen, but the production process is basically identical and that makes it very easy to make material in a GMP production process, which is the quality that you need for a human vaccine. For other platforms, for other types of vaccines, that might be a little bit harder because you have to adapt the production process and that comes with problems and can cause delays. So that's certainly an advantage. You have the specific advantage of different platforms too. Right, with vectored vaccines, often you get and I think Caroline will certainly address that point later on too you often get very good T-cell responses in addition to antibody responses.

For mRNA vaccines, again, the production process is completely free of any biological systems. It's basically chemically defined, which in a way can also be helpful because you don't get into problems with adventitious agents or a lot of different variability that you can get from biological systems. And then for recombinant protein production platforms, you have the advantage that you get a really defined product that you can modify with adjuvants, for example, and that can be very helpful too. So there is a lot of advantages to some of these platforms, and there is general advantages as well.

Perhaps I can add to that that if you compare it to the old AgPredictions platform and it was already a platform as well Basically that's where it all stems from. One of the disadvantages there is really that the switching to a new strain is more difficult, and the other disadvantage is that the production basically goes in cells originating from chickens, and that means that the way you want to induce protection is not always the same, basically because you use a substrate that is different from the human cell. So we find mutations then in the produced virus which are not advantageous or are away from the virus as it presents itself in the human cell, and I think that's an important advantage now, an important advantage of these technologies, now that you do use sequences that directly mimic what's happening in the real life in humans and animals.

And one of the risks, of course, for avian influenza viruses is that you have high pathogenic avian viruses that could actually kill the eggs that you need to actually produce the vaccine that you need to protect the population. So that is also an increased risk for vaccine failure in case of a pandemic, which these new vaccine platforms basically take away.

And I think the additional point here is also that for traditional ways of vaccine production for inactivated vaccines or even life attenuated vaccines you need to handle virus right. But for most of these new platform technologies there's no need to handle viruses or infectious material, and of course that's also health.

That also depends on the platform, of course. If you have vectored vaccines, so you have to handle the vector by definition and the vector should be safe obviously. So you have to handle the vector by definition and the vector should be safe obviously.

And how important was platform technology in developing the COVID-19 vaccines.

Well, I think, starting from the egg technology that I've been talking about, I think it is extremely important to see that all these different technologies that came about, many of them pre-existed already, but within a year, indeed, it was possible to have the first vaccines on the market, and that is both true for vectored vaccines, but also we have all learned about mRNA vaccines, and so it's really the speed. And then, of course, immediately for any vaccine that you're talking about is, on the one hand, it's safety, you know, and that's a major point but also effectiveness or efficacy. So that's an important balance that you always have to strike, and there are differences between the different platforms in that equation.

And I think what Florian already alluded to a little bit earlier is that one great thing that we saw with these new vaccine platforms is that they are not only able to induce these antibody responses, but a much broader immune response, including CD8 T cells, CD4 T cells, and all these extra immune functions help actually improve the protection against this novel virus as well.

Especially CD4 T cell responses that you were talking about, because that also stimulates, at least for influenza, the only real correlate of protection that we know to date, which is neutralizing antibodies, anti-ha, antibodies.

Yes, but several studies have also shown that CD8 T-cells if you have a high level of CD8 T-cells prior to a pandemic they're actually cross-reactive. So that means that you may not prevent an infection, but can actually prevent severe disease outcomes may not prevent an infection, but can actually prevent severe disease outcomes, and it's not a traditional correlate of protection that we're used to have, but it's maybe something we should think about that is also important to preventing severe disease outcomes.

I think to be fair, when we are talking about COVID-19, we also have to keep in mind that traditional platforms like inactivated vaccines did a a lot of good, were actually developed for SARS-CoV-2 quickly too, and were used throughout the globe, with the exception of North America and Europe, where they were not used or not used a lot. So I think the more different types of vaccine technologies we have in the case of a pandemic, the better. The more different types of vaccine technologies we have in the case of a pandemic, the better. You know the next time some might work, some might not work and we don't know which ones work. Last time with COVID-19, all of them worked right.

But it's risky to only set in on the antibodies, because antibodies as soon as a variant of concern comes up. If the virus changes a little bit, the antibodies start to fill. So you need a backup system, and that's where the CD8 T cells could be a good additional effect here, because they are cross-reactive and they will actually recognize the new virus strains that start circulating later on.

I think that's a very important point you make, and I would like to go back to the remark by Claire at the beginning when she said for most of the human viruses we have no vaccines yet, and so that has. The question is whether the new platforms are going to cater for that. But I think an important point that we didn't make yet and Florian alluded to the more classical way of making vaccines is indeed that, also the price on the one hand. Can we afford it on the one hand, but also can they be produced in lower and middle income countries, especially keeping in mind that if you look at the vaccination coverage for COVID-19 in Africa, it's far behind what we have seen in the other countries and it's partly due to the fact that we could not have any local production. So new platforms that would allow that and that are more easily accessible also to less advanced technologies I think that's an important point to make as well.

I have to say this is one of the liveliest discussions we've had at ESWI airborne, I think, because we're 12 minutes in and we haven't even got to talking about influenza yet, which is, I said at the start, would somehow be central to this episode. So, Florian, we were just talking about the experience of rapid vaccine development using platforms during the COVID-19 pandemic. How has this impacted on influenza vaccine development and what are the most prominent platforms being used here? Florian?

I mean for influenza. We already had a diversity of technologies used for vaccines on the market right Even before the pandemic. We had inactivated vaccines, we had life attenuated vaccines and we had recombinant protein based vaccines, which are actually doing pretty well. And now there's of course a lot of emphasis on developing mRNA based vaccines for influenza. There's a lot in clinical trials Partially there's results out from phase three trials already and I think a lot of these developments are in the late stage and should get licensed relatively soon, and I think then it will be important to see how these vaccines perform in the population when compared to the more traditional influenza virus vaccines.

It's also important to mention that we have for influenza already special formulations for older adults, which typically don't respond to seasonal influenza virus vaccines as well, and those include high-dose vaccines and adjuvanted vaccines. So we already have a lot of diversity there. The new vaccines will add to that diversity and in the long run we'll see if they outcompete the old vaccines, if they're similar or if they do worse, and I think the jury is still out on that.

One of the challenges here might also be how to measure your immune response. Coming back to the correlates of protections, all these new vaccines that we've seen during the pandemic are very well able to induce different types of immune responses, but we don't really know what level is required to give that protection against the severe disease outcomes. And that is one of the challenges that we are facing now is that if we really want to measure how well these new vaccine platforms work, we should probably broaden and see if we can develop new measurements and really set those correlates of protection for CD8 T-cells but also non-neutralizing antibodies and the CD4 T-cells, for example.

I mean, I agree with you from a scientific point of view. That's important. But what you typically do and that's why I also stress that the recombinant protein vaccines are very good those are vaccine effectiveness studies, right? So they're post-marketing studies that, for example, the CDC does they don't look at immune responses, they actually look at how well these vaccines prevent different grades of disease, right, and so that's what you have to do in the end, and with influenza, you can do that because these networks that measure that are in place. So you don't have to measure the immune response, which is basically correlating with protection. You can actually measure protection itself.

But that only works if you don't have any neutralizing antibodies in your vaccine. If you have neutralizing antibodies and it matches with the circulating strain, then you cannot teaser out what the effect is of other components of the immune system. So that may make it harder.

Well, not really, because you measure real-time vaccine effectiveness, right, and that's how you can also compare vaccines and that's what typically is done in vaccine effectiveness networks, right. So basically they're often based on test negative designs, but basically you don't have to look at immune response at all and of course you see the impact of mismatch. If there is a mismatch then the vaccine effectiveness is bad. But typically it's easy to compare vaccines, specifically if they have the same components next to each other.

But you don't contradict each other at all because I think, at the end of the day, in the effectiveness studies it might not always correlate with the neutralizing antibodies that we discussed before. So anyway, I think there is sufficient evidence, as Caroline mentioned, from studies that were carried out, looking at, for instance, cd8 responses pre-existing in the influenza pandemic, that that made a difference as well. And at the end of the day, as you said, florian, it's really the effectiveness measurement that will decide it. But still it's very important that the work, for instance, that Caroline is doing on CD8 responses, that's important as well. But I would like to bring in another point that wasn't discussed yet in this context, florian, because you talked about recombinant proteins as well, and I think it's fantastic.

But I think one of the things so we are talking about I call them the mRNA vaccine, I would call them Rolls-Royce vaccines, so really they are the highest standard there. But I used to drive a Volkswagen, you know, and I think the Volkswagen vaccine it might well be that if you use the baculovirus technology for expression of hemaglutinous, or we use fungal systems which are much easier technology-wise, give higher production rates, at the end of the day may result in much cheaper vaccines. I think we should keep an eye on that and when we are talking platforms, I think it's important not only to talk about the messenger vaccines and the vaccines based on viruses that express other proteins, but that we really look at those relatively simple vaccines like the baclo-based vaccines, the fungal-based vaccines, and especially for production in low and middle-income countries. I come back to that because we might vaccinate the whole world when we need, rather than only the high-income countries.

This is a very important point about the accessibility of these technologies. About the accessibility of these technologies and, florian, I think when we spoke about a year ago about flu vaccines, we also discussed the quest for the Holy Grail, right? You're a believer, as I understand it, in the universal flu vaccine. What has changed since we last spoke?

So you're right, I strongly believe that this can be done. The question is how long it will take. So not much has changed since the pandemic, right, there's. Actually. You know, a lot of focus was diverted to SARS-CoV-2 initially. We now see that successful candidates for example, j&j had a hemagglutinin stock-based vaccine are not further developed. I think they basically gave up on their whole infectious disease program. Other vaccine trials have failed. During the pandemic there were two peptide-based vaccines that have been or were being tested and they failed in phase three trials. So there's not a lot of progress. And I think the other problem that I see is everybody is now really interested in focusing on mRNA vaccines that are basically similar to current seasonal vaccines and that's the focus of the industry right now and not actually inducing broader immunity, and I think that is a big challenge. So actually not much has moved. There is advances, but they're incremental right now. You know clinical trials are starting again, but I wouldn't expect a big jump in the next few years.

Perhaps, florian, it might be good to say so you are a believer in, let's say, vaccines that protect against all the strains of influenza, and so am I. I think that's where we have to go, yeah, but it's not easy, and I think it's really important to think out of the box as well. So we thought the stem antibodies were going to be the solution to everything. Yeah, it hasn't moved forward so fast, and that's partly due to the last pandemic as well. But I think what Caroline said is quite important, that if we look at the correlates of protection, we might actually profit more from that.

And you said the peptide vaccines didn't make it so far. I fully agree. But I think there is a real potential there that if we can make vaccines, that perhaps at the end of the day they don't give full protection but they mitigate the disease. I think that would be an important point. So I strongly believe also that what Caroline is saying about these T cell responses being CD4 responses, cd8 responses, what have you? They deserve more attention in the future. Do you agree?

So I have to out myself here. I'm actually a pretty big fan of tissue resident memory T cells in the upper respiratory tract. I think they can make a huge difference, but we haven't figured out how to induce them efficiently and how to keep the levels high. I think that's another challenge, right? So I think there's a lot to explore, and I think that goes back to new technologies. You can actually include other antigens into mRNA vaccines, for example, and drive really strong responses against nuclear protein, for example. But again, we're talking about things that are explored pre-clinically and once you go into translation it's harder to include that. And in the end again you have to look at vaccine effectiveness and see if that really works out. So I think there is a lot more tools now to play with. But again the proof is in the pudding and you have to move it into the clinic and then show that the vaccines work, and that takes a lot of time and is very complex.

And one of the challenges that you have with measuring these other correlates of protection is that it's probably not as easy as that we do for antibodies. Where it's relatively easy and quick assay you can screen a lot of people really fast, whereas an assay to measure T cells is really expensive. You need very highly specialized people to do the assay and, yeah, it's not as easy to screen a lot of people that quickly. So that makes it more challenging as well to set those bars for correlative protection.

And I completely agree. But I think the other issue is also that if you want to have a correlative protection that you use for in the end licensure vaccines, you also need assays that are reproducible between labs that always give you the same readouts. You know you kind of need to set quantitative measures, and I think that's even with antibodies. During SARS-CoV-2, we struggled doing that right and, as you said, with T-cells that's even more complex.

But one of the big issues there and Caroline didn't mention it yet, but I think it's a very important point in the T-cell response. So they're genetically restricted. So it depends on your genetic background whether you respond to certain epitopes yes or no, and that is a major thing as well. So, as a matter of fact, in the approach that you are interested in, you would have to take that into account and probably would have to go into polyepitopes and all kinds of more difficult things, whereas an antibody is an antibody and it works in every person, even in an animal it works.

So also the preclinical work, apart from some, some studies that you can do in in transgenic mice. But the pre-clinical work is extremely difficult as well. But I don't want to discourage you, Caroline, because there have been more serious people, people have gone to the moon, so

I'm certainly not discouraged and I fully agree. The hlas make it very hard. But it also makes why the cd8 T cells are that good, because we are all genetically different. It makes it way harder for the virus to escape the CD8 T cells.

All right, it's unusual to hear Abastra House concede the last word there, but I think it just happened. Ladies and gentlemen, are there any specific concerns about safety in relation to vaccine platform technologies?

There are. I mean, for each type of vaccine you have concerns or you have safety signals. It always depends on what the frequency is. Vaccines that are licensed have a typically low frequency of adverse events, otherwise they wouldn't make it through the licensure process. But I think what we've all experienced with mRNA vaccines is that the reactogenicity basically the response right away after vaccination can be relatively strong. Some people, when they get mRNA vaccines, they feel sick the next day. That's something that's relatively specific to the mRNA vaccines. That's also something that can be addressed in the future by changing formulations. We have seen specific issues with vectored vaccines during the pandemic, again at low frequency, but they have been detected. But in general the safety concerns are similar to other licensed vaccines where there are specific signals that you see at low frequency, and so I don't think that we are overly concerned about these new technologies versus the old ones that we already have.

Well, I think it's important to realize that there's always this balance between safety and effectiveness. How many lives are you going to save? And if you just look at the figures that we know also from WHO at the moment, the tens of millions of lives that have been saved on the one hand, and we then look at how many cases of adverse events, how bad they are, we know that, but that's true for all the different technologies, as Florian said. But it's all in the game. Of course, perhaps it's good to realize we have eradicated smallpox with a vaccine that for these reasons, for safety reasons, would not be acceptable today and we have saved so many millions of lives with the vaccine. I remember I was vaccinated with that vaccine and that was a long time ago, but at that time we accepted very severe, very severe side know, encephalitis and things like that in, let's say, in frequencies that would be outrageous to be accepted today. So I think it's important to always look at that balance.

But if you get the disease circulating, how many lives can you save? And then, of course, on the other side of the coin is always that you may have side effects, but they are. I think on the other side of the coin is always that you may have side effects, but they are, I think. For the technologies that also Florian mentioned, I think they should be considered acceptable. But that's always a thing to be considered all the time. Weigh these two things against each other. In what population can we use what vaccine? What's the benefit and what might be the harm? And let's be honest, you know, when we develop vaccines, let's inform the public at large of these two things, and I think that's to be fair.

And I think it's also important to remember that minor side effects can actually be a good thing. It's your immune response, your immune system responding to the vaccine. That's what's giving you a sore arm, that's what maybe makes you feel a bit wobbly in a couple of days afterwards, but that is your immune system actually responding to the vaccine and actually making all those antibodies that you need to protect you against infection.

Yeah exactly Antibodies.

And the T-cells as well.

T-cells too, against severe disease.

You said antibodies.

Yeah, I believe in antibodies too. I think it's a combination of the two that makes it good.

Oh, it's good that we have a consensus there. We all agree that basically, at the end of the day, as Florian said, it's the effectiveness that counts. But then the side effects. On the one hand, a sore arm has nothing to do. If you have a pandemic, you know a sore arm should not be neglected.

But it's really how many lives are you going to save

And is there a dedicated regulatory regime? Or vaccines developed using platform technologies, or the same regulation applies as in how they make it to market? There's no difference, is there?

Everything needs to go through the same regulatory route. There's nothing special in terms of the regulatory framework for new vaccine technologies versus old production technologies. You have to basically go through the same testing, you have to show the same safety records, you have to show basically the same vaccine effectiveness, vaccine efficacy. So the same rules apply to everything.

Perhaps it's interesting to say that in Europe at the moment EMA has really adopted also platform technologies for the veterinary vaccines. That means that it's much easier if you have vaccine against virus in the same families. It's much easier to go to the vaccine for the next virus. And it's being considered now by EMA for human vaccines and also FDA to take these platform technologies more serious and make it possible to very rapidly act, as has been done already during the last pandemic.

And EMA, that's the European Medicines Agency. Yes, yeah, okay, I really want to chat with you guys all afternoon, but we've all got jobs to do, I guess. Looking into your crystal ball, or even into what you most long for, what do you want to see? What do you most want to see happening in relation to vaccine platform technology in the short term?

I wish that Florian and Ab both accept CD8 T-cells as a possible correlate of protection, and they just did so. My short-term goal is there.

All right, there we are Inspiring women in science science. Don't forget to vote.

I think there's a bunch of things. The question about vaccines is not just can we make them and are they effective. The question is, are are people? Are they? Are they reaching people right? And you run into different issues here. One, as I, as I pointed out, is accessibility around the globe. Can they be produced locally, which is really important in case of a pandemic, right, and so having advances there and maybe technologies that can be produced everywhere, that would be something that I would personally really like to see. The other thing is and I mentioned that, this rectogenicity right, people need to be willing to take these vaccines.

Right now, we have a lot of concerns that people have about mRNA vaccines versus other technologies, right, so you could have a wonderful mRNA-based vaccine, but, for example, in the US, if the population is not willing to take that vaccine, you still don't have a vaccine, because if nobody takes it, it doesn't help, right?

And so I think, also, their advances in terms of reducing reactogenicity would be very, very important. And the other thing that I really would like to see is, specifically, when we talk about mRNA vaccines against influenza, there are no choices. Right, you can use hemagglutinin and basically focus everything on hemagglutinin and make next generation vaccines based on HA that target HA like the traditional inactivated seasonal vaccines. But you can also make the choice and go the extra mile and add other antigens, neuraminidase for example, maybe even nuclear protein or matrix protein, and you might get broader production. This might be much harder to demonstrate in a phase three trial. That might cost a lot more money to develop. But if you don't do it you throw out the chance to make a better vaccine and I would like to see vaccine companies doing that, trying to make a better vaccine even if it costs more money to develop it.

Well, that sounds fantastic. I would like to echo the two points you made at the beginning. So, on the one hand, the low middle income countries, that we can have vaccines being used there as well, either through production on site or whatsoever other mechanisms. You know, accessibility. And the other thing we haven't addressed during this whole episode is the fact that there is a growing number of people who don't like vaccines the anti-vax community and you alluded to that as well, florian. But I think we can make vaccines that are 10%, 20%, 30% better, but if 10%, 20%, 30% of people don't use them, who have access to them don't use them, I think that's a major thing. So we should really invest there, because we have seen during the COVID pandemic that that is a major problem. And then, finally, the two other issues, of course, because we are dealing with a lot of people who are against animal experimentation, the preclinical work.

I fully agree that that is a major thing that we have. I'm a veterinarian by training, so I think it is absolutely, absolutely crucial that we get the understanding under what conditions we can use animals. We don't want to test all the vaccines initially on humans, because we cannot do that. And then the last point I would like to make is and we haven't mentioned that yet, but apart from all the other issues we mentioned, I think it's fantastic the number of people who are willing to participate in clinical trials. So I think that's a very important thing, because when we bring a vaccine to the market, you go basically after the preclinical stage where we use animals, then you go to phase one, phase two, phase three, and I think we are really very grateful to people who really participate in those kind of experiments as well, and I'm not saying they're taking major risks, but if those people would not be there, it would be very difficult to eventually develop vaccine with the speed that we have actually done during the COVID pandemic. So those are, for me, the major points.

And up to your last point, I think we have to lead as examples right, and, for example, I was in the phase three trial for the Pfizer vaccine and I'm pretty open about that. I discussed it and I think we as vaccine researchers should not be afraid to sign up for these trials, because that shows that we think they're safe and we think that these vaccines can work Right. I think that's also an important point.

I fully agree there, but there are some legal restrictions there as well. I've participated in many of those things, so, and I think it's important to show that we have the confidence there by doing it ourselves, but it's not always possible due to ethical restrictions as well. Anyway, I think this point of people including ourselves being willing to take these vaccines before they have been tested in thousands and hundreds of thousands of people, I think it's an important thing and we should be grateful to them in these clinical trials because usually these vaccines are tested in individuals who are in general good health and are having a good immune system that responds well to the vaccine.

But high risk groups like the elderly, people on immune modulatory medications they may not have the same effect there and it's important that we also test those vaccines in those groups to see if they work just as well as they do in a normal, healthy individual.

Thanks a lot for that, Caroline. So, if I can, I can't possibly sum up all the places we've been, but I'll note a few of them anyway, of the work we've got to do. Yet addressing hesitancy, making these technologies accessible and vaccines accessible, enabling the preclinical work and participation in clinical trials are most important. So keep showing up, Florian, Caroline, Alb thank you so much for joining me today in this great discussion.

Thank you.

Thank you for herding this group of scientists.

Like herding cats, I suppose. So, folks, if you've enjoyed as much as I have having your mind blown several times during this discussion on vaccine platform technologies and other topics, then stay tuned. Today's episode is one of a four part series on intervention strategies. In other episodes we'll be honing in on RSV, plus all the latest on COVID-19, including new therapeutics in development and long COVID, and finally a bonus episode covering flu, covid and RSV together, which will be co-moderated by ESWI chair Colin Russell. Don't miss it and keep tuning in to get the latest on intervention strategies from experts in the ESWI network. And until next time, dear listeners and my lovely panelists today, stay safe.

Aida Bakri: 37:15

ESWI Airborne is brought to you by ESWI, the European Scientific Working Group on Influenza and other acute respiratory viruses. These episodes would not be possible without the team's efforts and we would like to extend special thanks to our ESWI secretariat, our technical and IT teams, our arts team and our host, claire Taylor. The podcasts are recorded virtually and we thank our guests for their participation in this inspiring series. Talks are adapted to a global audience and are intended to be educational. For any specific medical questions you may have, these should be addressed to your local general practitioner.

Flu vaccines - advancements, challenges, and global impact

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