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The Dose Transcript for October 3, 2024

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. Well, we're getting into another autumn and winter flu and respiratory virus season. This year, provinces and territories will be distributing three kinds of vaccines; flu shots; the latest COVID-19 boosters. And, you know, vaccines, I guess they can also be called immunological products for respiratory syncytial virus or RSV. So this week we are asking: Which vaccines do I need this fall? Hi, Susy. Welcome back to The Dose.

DR. SUSY HOTA: Hello. It's nice to be here.

BRIAN GOLDMAN: So do you know anybody who's driven down to a U.S. border town to get the latest COVID vaccine?

DR. SUSY HOTA: I do not, actually. But, yeah, I hear that this is a challenge this year, isn't it?

BRIAN GOLDMAN: It is, you know. Because people are waiting, you know. You know, I guess it's a good thing if you have the public being sensitized to wanting to know when they can get the vaccine. You know, there are people who are immunocompromised. So that's good. That means that they're aware of it. And that's why we wanted to turn to you because you're an expert. But before we begin, can you give us a hi, my name is? Tell us what you do and where you do it. Just ad-lib.

DR. SUSY HOTA: My name is Susy Hota. I am the Division Head for Infectious Diseases at the University Health Network and Sinai Health in Toronto, and also the Medical Director of Infection Prevention and Control at the University Health Network in Toronto.

BRIAN GOLDMAN: So a bit of a general question to begin. What's your best scientific guess on how bad RSV, the flu and COVID are going to be this autumn and winter?

DR. SUSY HOTA: It's such a great question, but incredibly difficult to really predict. And that's because each of these viruses acts unpredictably. And COVID more so than the others, because it's less established in terms of its patterns of how it's transmitting. I mean, what we know is that influenza and RSV tend to be seasonal, which means we see an increase in activity typically around November of every year, and it lasts until April or May. But every year it can look a little bit different in terms of when the activity peaks, just how high it gets in terms of the number of cases we see; how long it can last; how intense it is during that entire time. So, you know, the patterns are actually pretty relevant in terms of what it feels like on the ground to be experiencing it. So all this said about the unpredictability, the things that we sometimes look at is, what was it like last year? Because that often helps us to understand what it could look like this year. What was it like in the Southern Hemisphere? Because that often mirrors what we will see in the Northern Hemisphere following it that season. Although, it doesn't always predict what we're going to see.

BRIAN GOLDMAN: So that's true for the flu. Is it true for COVID and RSV?

DR. SUSY HOTA: Less so for COVID. COVID's a bit different. RSV and the influenza virus, yes, we can sometimes get a little bit of a hint from other countries that have experienced it before we have. But what I was going to say about COVID is, the patterns are less well-established. And so sometimes it's also just helpful to know what's happened in the months preceding the fall. Did we have a lot of COVID through the summer, or did we have a relatively quiet summer time? Because if we had a quiet summer, as we kind of did this year, then we can maybe expect that we've got more susceptible people in the population, and so we could see more of a fall wave.

BRIAN GOLDMAN: Speaking of COVID, what's the dominant strain of COVID in Canada right now?

DR. SUSY HOTA: Right now there's a strain that's called KP.3 and its subtypes or lineages -- so, derivatives of it -- that are circulating the most in Canada. So more than 70% of our strains are matching this subtype of COVID-19. So, we know about this. We expect that the next wave of activity is going to include this wave and likely be driven by it. Although, we do see many different subtypes of COVID-19 always in the background. So, you know, really important to keep an eye on that genomics and how things are evolving in Canada as well as in other countries.

BRIAN GOLDMAN: There is a newish kind of subvariant that I've seen out there referred to as COVID XEC. What can you tell us about that?

DR. SUSY HOTA: Yes. So this is a variant that's circulating in parts of Europe and some other countries. There is some thought that perhaps it's more infectious than what we're seeing right now with the KP.3 and others, but I don't think we know very much about it yet in that sense. Certainly, it doesn't seem like it's causing a different kind of disease in people who are getting infected. Right now we see small numbers of this variant in Canada, but it is not showing in larger numbers or dominating yet. So, yes, we definitely have our eye on that one.

BRIAN GOLDMAN: Let's turn to influenza. What's predicted to be the dominant strain of flu this year? It'll be an influenza A, won't it?

DR. SUSY HOTA: It will be usually influenza A that dominates in the beginning. And then later in the season we tend to see a pickup of influenza B just as things are subsiding with influenza A. That doesn't always happen, but when influenza B does appear, it tends to be a little later in the season. And in terms of influenza A, there are two major subtypes that we see. There is H3N2 and there is H1N1. And it's a little hard to know at this point which is going to be the more dominant subtype of influenza that's going to cause disease in the Northern Hemisphere this year. Because in the Southern Hemisphere we mostly saw H3N2, but there were some countries that had H1N1 predominantly.

BRIAN GOLDMAN: A question that everybody wants to know is how effective this year's flu shot is going to be. And, you know, from what I know, we don't know the answer for the upcoming flu season. We only know for this year, and I gather it was somewhere around 51%.

DR. SUSY HOTA: Exactly. So, this is the challenge we face with influenza vaccines. Everyone wants to know what the vaccine effectiveness is going to be for the flu shot in the upcoming season. But we only really get the data at the end of every season after we've rolled it out and we have a sense of, you know, how well things panned out. So in the last season, it was, it was moderate. It was around 51%. I will say, in general, we can provide a range of about 40 to 60% effectiveness of influenza vaccines year to year, and that generally covers what we've seen in the recent past at least. So I would say influenza vaccines, you can expect a moderate effectiveness in preventing influenza. But where it really shines, like all these other vaccines, is having an impact on hospitalizations, on complications of influenza, and death in those who are the greatest at risk.

BRIAN GOLDMAN: So we've talked about the flu, we've talked a bit about COVID-19. I want to ask you about RSV. Do experts actually watch strains or subtypes of RSV the same way they watch the flu?

DR. SUSY HOTA: They don't. You know, I think that this is something we're going to have to look at a little bit more now. Especially, that we have these new vaccines and other sort of immunologic therapeutics to prevent infections in RSV. We're going to want to know if we are targeting, you know, what is circulating. So, that is something that, as a public health, you know, decision-maker, we're going to have to start looking at a little bit more. What does RSV do year after year and season after season.

BRIAN GOLDMAN: We're going to move into talking about vaccines now. We've talked a little bit about flu vaccines. I want to ask you a practical question: when should people get their flu shots this year?

DR. SUSY HOTA: People should get their flu shots this year when it becomes available. Usually that's at the-- towards the end of October. With influenza this year, I started off by saying we don't really know how it's going to behave. If you look at last year, really-- activity of influenza started to pick up around November and peaked in January. So, you know, if we expect a similar year to that, getting your vaccine in October will prepare you for activity that would probably start to rise through the middle of November. So I would say late October is the best time, when it becomes available.

BRIAN GOLDMAN: And how long, how many days does it take to become effective?

DR. SUSY HOTA: With any vaccines, you have to wait at least 10 to 14 days for your immune system to generate enough antibodies to protect you against the virus. So it's not an immediate effect. You will have effect for a period of time. And the other thing to be aware of is they don't last forever. Which is why it's important to get influenza vaccines annually, for example, and to get COVID-19 vaccines on the basis that they're actually recommended. Because your immune system can wane in terms of the effect of protection over time.

BRIAN GOLDMAN: Let's talk about what's out there to protect people against RSV. All of them aren't strictly vaccines, are they?

DR. SUSY HOTA: That's right. So with RSV it's a bit confusing, I think, because, number one, these are newer products to us. So it always takes a little bit of time to become familiar with them. But secondly, there are two different types of products that we're talking about for prevention. One set is vaccines, and there are two vaccines that are available right now. And then, for infants in particular, there are these things called monoclonal antibodies, and what they're doing is giving your immune system sort of what they cannot necessarily make themselves, because infants don't have a mature immune system. And so it provides the antibodies for them passively, as we say. And so there are two products that are available for young children and infants this year.

BRIAN GOLDMAN: And it's a reminder that there are several risk groups, and we'll kind of take them one at a time. You mentioned that there's two vaccines that are available for seniors. What can you tell us about those?

DR. SUSY HOTA: So there are two vaccines that are available. They're called Arexvy and Abrysvo. And the indication here are really for older adults. So, adults over the age of 75 or over the age of 60, who live in long-term care and congregate settings. Things like that. That's really the targeted age group. And the reason being, for RSV, where we see the more severe complications tend to be elderly people as well as young infants and young children. So, those two vaccines are available for older adults. Now, we want to protect young infants as well, and there are two ways that that can actually occur. You can use one of these vaccines in pregnant women who are at the end of their pregnancy -- so in their third trimester, usually around 32 to 36 weeks of pregnancy. And if their child especially is going to be born during the respiratory virus season, as we call it, then you would really want to make sure that they're protected. And the idea here is if you immunize the mom while they're still pregnant, the antibodies that are made from receiving that vaccine can travel through the placenta and into the baby and protect them for up to six months after they're born. And that's a period of time where the immune system really is much less mature and they're at greatest risk for getting sick. So that's how the vaccine can be used to help protect infants. Now, the other two products, the monoclonal antibodies, like I said, are actually a preferred way of trying to protect the infants. They seem to work a little bit better. There's one that's been around for quite a while -- it's called Palivizumab. And it has to be given monthly to infants during the period of risk. So you can imagine, through the season. So these-- this would be valuable for young infants who are at risk for infections that can be severe. But there's a newer one that came out called Nirsevimab, which only requires one dose to be given and then can protect the infants through the season. Those are kind of the newer products that are a little bit different from vaccines, but are going to be, you know, really important, I think, as tools for prevention.

BRIAN GOLDMAN: And are these kinds of medications indicated for all infants or primarily infants at risk?

DR. SUSY HOTA: So, there are a number of very specific criteria, and I think what I would say is sometimes these things vary a little bit from area to area depending on where you live within Canada. But infants who are entering or born during their first RSV season who are at increased risk for severe disease, and that includes some babies who are born less than 37 weeks of gestation, so if they're born early. Or infants who are actually entering into their second RSV season, so they're a little bit older, but who have an ongoing increased risk of severe disease because they're either born early, so pre-term birth, or they have chronic lung disease, or they're very immune deficient so their immune systems don't function well. And then there's a whole number of other sort of listed diseases as well. Those are the main groups. And then there's some other specifics as well that are outlined in different eligibility criteria.

BRIAN GOLDMAN: Are vaccines like Arexvy in seniors recommended for all seniors or only seniors at risk? And the reason why I'm asking is that very few provinces actually cover them. And there's a big difference between Ontario and Quebec.

DR. SUSY HOTA: It's a tricky thing, because if you look at where the data lie, it's really based on your risk factors. And age itself is a risk factor. So, you know, scientifically speaking and looking at how the studies were conducted, the target is older adults. So, you know, the older you are, it's sort of an incremental risk increase as you get older. But certainly over the age of 60, you are going to potentially benefit from these vaccines. The problem becomes there's a difference between what you would scientifically recommend, and what the eligibility criteria then become from provincial governments that are then creating these publicly funded programs and trying to implement across the province. There is variability, unfortunately, across the provinces, and so the best thing to do is to look up where you live and what is actually covered and what would be eligible.

BRIAN GOLDMAN: What do we know about side effects and potential harms from these products?

DR. SUSY HOTA: All these vaccines are well-tolerated and, and safe. They would not be authorized by Health Canada if they were not. That said, people may have allergies to specific vaccine components, and you need to know that. So if you've had an allergic reaction, a serious one, to a vaccine like an influenza vaccine or a COVID-19 vaccine in the past, then you should, of course, speak with your health-care provider about the safety of proceeding or whether you should not be getting this vaccine. Know about reactions, know about allergies. But in general, these are very safe vaccines. Everything may have a side effect, so if you do want to get counseling on that because you're not sure about your own personal health and whether it's a good idea to go ahead and get one of these vaccines, please do just book an appointment with your primary care provider and go through, you know, your specific scenario.

BRIAN GOLDMAN: Let's talk about COVID vaccines. When should people get their COVID-19 vaccine? Obviously, that's going to depend on whether or not they've had a recent COVID infection and how long it's been since they had their last vaccine, so. Let's see if you can tackle that.

DR. SUSY HOTA: Yeah. So with the COVID-19 vaccines, I think we feel that this year in the fall, you know, it's an updated vaccine that's available. It's different from what you've had before. So it's slightly different, it's not like we're just trying to boost your immunity, you know, using a similar vaccine to what you had before. So there is a little bit more of an interest in getting people vaccinated in the fall. With this, if you've had a COVID-19 infection, you should wait a minimum of three months because you're already protected from antibodies you would have generated from that infection. And it doesn't make sense to then get your vaccine. You can extend the period of time that you will be protected if you wait at least that three months and then get your COVID-19 vaccine. The frequency between vaccinations or an infection and vaccine -- the recommended period of time is every six months, as per the National Advisory Committee for Immunization, or NACI, who puts out a lot of these recommendations based on science and feasibility and a number of weighing of ethical factors as well.

BRIAN GOLDMAN: Do we know how effective these new vaccines will be against COVID?

DR. SUSY HOTA: Because there are always new strains that are being targeted by these updated vaccines, it's hard to actually quote real life experience. It's all very preliminary in areas that would have been rolling out these newly authorized vaccines. The sort of early signal is it's going to be similar to what we saw before. So probably moderately effective, 50 to 60% effective in terms of reducing infection risk. But again, more effective, a stronger protection against severe illness, hospitalization, death. Those, you know, outcomes that we're really interested in preventing for COVID-19.

BRIAN GOLDMAN: It's, I guess, a bit of a coincidence that the newest COVID vaccines will become available somewhere around the time that flu shots will be available. Can you get them together?

DR. SUSY HOTA: You sure can. And I think we're getting more and more comfortable with that recommendation as more data has come out on concurrent, as we put it, you know, receipt of these vaccines. They can be given together in any combination. Now, you've got two arms and you've got three vaccines we're talking about all coming out around the same time so, maybe choices will have to be made. And some people do prefer to space out their vaccines just because they tend to get more of a local reaction, which is, you know, kind of to be expected in the majority of people. That you'll get some kind of a sore arm or maybe a bit of swelling. And so if you want to space them out, you may do so. And there's no minimum period of time that you have to wait between getting another vaccine and getting your COVID-19 vaccine, for example. And so, you know, I think that's good because it gives us flexibility to decide what we need to do. It should not affect the safety or the effectiveness of your vaccines if you're getting them at the same time or overlapping periods.

BRIAN GOLDMAN: How effective are the latest RSV vaccines and immune products for seniors and for infants and young children, as you were talking about before?

DR. SUSY HOTA: RSV vaccines are actually pretty good. When it comes to older adults, those two vaccines that I had mentioned, they are 80% effective, on average, in reducing what we call lower respiratory tract infections. These are the more serious respiratory infections that often land people in hospital. When it comes to more serious outcomes, hospitalizations and deaths, they're more than 90% effective in reducing that in older adults. So, very helpful and potentially can have a big impact on people's lives. Now, when it comes to giving the vaccine in pregnant women to try and prevent infections in their young infants, it's a little less effective. It's more in the 60% range of reducing those infections. But if you use those monoclonal antibodies like the one that I had mentioned, Nirsevimab, has recently come out, it is more effective. It's again, in that 80% range of reducing important respiratory infections with RSV in the infants.

BRIAN GOLDMAN: And will pregnant women be prompted as part of their prenatal care if they want a vaccine or... you know, how does that work?

DR. SUSY HOTA: I certainly hope so. I mean, I don't participate in that kind of, you know, antenatal care, as we call it. But, you know, I think this is an area of opportunity for sure. We should be asking and counselling and talking about vaccines in pregnant women, because there's, there's this, there's also other vaccines that we should be encouraging people or reminding them to get. Like pertussis vaccine because we are seeing more whooping cough, a different kind of respiratory infection right now. And this is an important way to protect young infants, again, through the mom's antibodies going through to the baby after they're born. So there are other vaccines, and COVID-19 is another one where we would encourage that in pregnant women. So I really hope that this kind of counselling is happening because it can have a big impact on, you know, young, vulnerable babies after they're born. And it is something that we're not always so great at doing.

BRIAN GOLDMAN: You mentioned whooping cough, and we just happened to do a Dose on whooping cough quite recently. What other infectious diseases are circulating out there or likely to circulate out there for which vaccines and boosters might be indicated?

DR. SUSY HOTA: There are many. But since we're talking about respiratory infections, there's also bacterial respiratory infections that cause pneumonia that land people in hospital. And again, it's often the extremes of age that we're talking about -- older adults and young children. And there is one vaccine type against what we call pneumococcal disease or invasive pneumococcal disease. And so that's something that, again, people need to make sure that their children are caught up and on their immunization-- childhood immunization schedule, because there is protection that can be given through that immunization schedule for the pneumococcal diseases. But also, when you're over the age of 65, you can, you know, get a pneumococcal vaccine as well to protect you at that stage in life. And so that's one example. But, you know, many things, like measles, mumps, rubella, vaccines. People have, especially over the pandemic years, fallen off of the schedule, so young children may not be fully vaccinated. And it's a good reminder, I think, when we talk about these respiratory viruses and these vaccines that are are going to be things people are considering in the fall, to also think about these routine vaccines.

BRIAN GOLDMAN: Well, Dr. Susy Hota, that was a very eclectic episode of The Dose. You handled a complicated topic because it's broad and involves lots of different vaccines and viruses and, and bacteria even. So, thank you so much for enlightening us and coming back once again onto The Dose.

DR. SUSY HOTA: It was my pleasure. Thanks for having me.

BRIAN GOLDMAN: Dr. Susy Hota is Division Head of Infectious Diseases at the University Health Network and Sinai Health. She's also the Medical Director of Infection Prevention and Control at UHN. Here's your dose of smart advice. This fall and winter, we can expect to see spikes in respiratory infections, primarily from three kinds of viruses: influenza, COVID and respiratory syncytial virus or RSV. Fortunately, vaccines and other immunization products are available for these viruses. Let's begin with flu shots. For the 24/25 Northern Hemisphere flu season, the WHO recommends a vaccine that protects against two strains of influenza A and one strain of influenza B. The new addition this year is an H3N2 flu strain of influenza A. Last season's flu shot was 51% effective, but we won't know how effective this season's flu shot is until well into 2025. Flu shots should be available to the general public near the end of October. Check with your local public health authorities to get more precise dates where you live. COVID continues to be an ongoing source of respiratory infections. The KP.3.1.1 subvariant is now dominant in Canada. The Public Health Agency of Canada says another subvariant named COVID XEC has been detected in this country. Experts predict this new strain will cause a surge in COVID infections in fall and winter, but will not lead to a huge increase in hospitalizations and deaths. This month, health Canada approved an updated version of Novavax's COVID-19 vaccine, as well as an updated Moderna COVID-19 vaccine called Spikevax. An updated version of a vaccine by Pfizer has also been approved. The Public Health Agency of Canada said the newly updated vaccines will help protect against serious disease caused by related strains of COVID, including XEC. These updated vaccines should become available sometime this fall. It's safe to get a COVID booster and a flu shot at the same time. Health Canada ordered older versions of the vaccine to be destroyed as the new ones become available. RSV infection continues to be a major cause of lower respiratory tract illness, particularly among infants, young children and older adults. There are several immunization products that protect infants against RSV. They include two monoclonal antibody preparations, which are administered directly to infants. As well, a vaccine called Abrysvo can be given during pregnancy to help protect the baby following birth. Abrysvo, and another vaccine called Arexvy, can be given to adults aged 60 years and up, to protect them from RSV. Check with your province regarding coverage. Ontario and Quebec are the only two provinces currently rolling out fall RSV immunization programs for newborns. Coverage for seniors also varies across the country. If you have topics you'd like discussed or questions answered, our email address is thedose@cbc.ca. If you like this episode, please give us a rating and review wherever you get your podcasts. This edition of The Dose was produced by Sameer Chhabra. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health-care provider. I'm Dr. Brian Goldman. Until your next dose.

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Which vaccines do I need this fall? - Transcript

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