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The Dose Transcript for September 26, 2024

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. Cases of whooping cough -- do you call it hooping cough or do you call it whooping cough? -- also known as pertussis, are on the rise across much of Canada, breaking records in some provinces. So this week we are asking, what do I need to know about whooping cough? Hi, Cora. Welcome to The Dose.

DR. CORA CONSTANTINESCU: Hello. Thanks for having me.

BRIAN GOLDMAN: You practice in Calgary, so how much pertussis or whooping cough are you seeing at the moment?

DR. CORA CONSTANTINESCU: I practice in Calgary, but I am an infectious disease specialist so we see the tip of the iceberg. We see those kids who end up in hospital quite severe, often needing ICU stays. So, I don't see a lot of it in day-to-day life because, you know, it's a, it's a different demographic that we do see. But I tell you, I hear more and more from my friends and acquaintances about them having pertussis or their kids having pertussis or fellow health-care providers telling me that they were diagnosed with pertussis. So it's here, and probably a lot more than we know.

BRIAN GOLDMAN: And we're going to get into the reasons why in just a moment. But before we do, can you give us a hi, my name is? First and last name. Tell us what you do and where you do it. Just ad-lib.

DR. CORA CONSTANTINESCU: Hi, my name is Cora Constantinescu. I'm a pediatrician and an infectious disease specialist. I work at the Alberta Children's Hospital in Calgary, Alberta. I'm also affiliated with the Cumming School of Medicine with the University of Calgary as a clinical associate professor.

BRIAN GOLDMAN: Okay, let's begin with the basics. What is pertussis or whooping cough?

DR. CORA CONSTANTINESCU: Whooping cough is a disease caused by a bacterium called Bordetella pertussis. The 'whooping' part of the name comes from the fact that when it's in what we call a paroxysmal stage, so the stage where people cough and cough, people cough so much and the airways are so narrow and blocked that when they take a big breath in, you hear a 'whoop.' And especially you hear that in children. So, in children between, you know, one and five years of age, for example, it's much more common to hear the whooping aspect of this. But the disease itself is a very long disease. So it starts in the first week or so with very nonspecific symptoms of fever, runny nose, cough. It looks a bit like a cold. And then that paroxysmal stage that has given it its name, the whooping cough, starts, and that lasts for about three, four weeks. And then there is a stage of what we call convalescence. So that's when you try to recover in the subsequent few weeks. But people can still have significant cough. So overall, this disease is incredibly long. And this is why sometimes you might have heard it's called the 100-day cough, just because it has all these stages and people cough for so long when they have it.

BRIAN GOLDMAN: I had it. I was about 12 years old when I got it, and I can remember my cough reflex was twitchy. It was very sensitive for months afterwards. And if I got a cold, I'd start to cough frequently. And the whooping, you know, I know what that's like. You know, when you're cough, cough, cough, cough, cough, 10 or 15 times in a row, you can't catch your breath. And that's what that sharp intake of air is all about.

DR. CORA CONSTANTINESCU: Exactly. And little babies who cannot whoop end up just not able to breathe, which is even scarier. But that's exactly-- you gave it a perfect description. I think it's a misnomer that it's called the convalescent stage. Because people will describe that the smallest trigger -- it can be another cold, but it can also be just cold air, for example -- will send them back into these episodes of just unable to stop coughs. And people lose sleep. They're incredibly fatigued at the end of these two months of illness.

BRIAN GOLDMAN: How contagious is whooping cough?

DR. CORA CONSTANTINESCU: It's fairly contagious. It spread through the same respiratory droplets that a lot of infectious agents are spread via. So, viruses, for example. But what makes this particularly bad is that it may not be, for example, as infectious as measles, but it's infectious for a long time. So this period of infectivity can last through that whole period, where people just have a cold-like presentation -- so when you just have the runny nose and the fever and a bit of the cough -- for a whole three weeks once the whooping cough stage starts. So you can imagine that there's probably a good month where you're contagious with this disease. So the reason it's spread so well is that it's highly unlikely that people who have this illness are going to stay home for a whole month. So this is why it makes it so contagious, because you've got people moving around, coughing, spreading this by these respiratory droplets. So anybody in contact with a sneeze or a cough or with the droplets on objects they might have been spread on, can then get it.

BRIAN GOLDMAN: Ontario is breaking case records right now for whooping cough. Where else are we seeing outbreaks?

DR. CORA CONSTANTINESCU: Whooping cough is already called an endemic disease in Canada. In other words, we always have a bit of a low-level activity. And then every now and then we get these occasional-- every two to six years we get occasional outbreaks. So it's not unheard of, for example, to have a whooping cough outbreak. Prior to the pandemic, in the last 15 years, we had had about 30,000 cases of whooping cough. And I want to put this a little bit into perspective about what I'm going to say next. But what's different about this year is that our numbers are really high. So, for example, Ontario has reported over a thousand cases, but Quebec has reported over 11,000. And then we know that New Brunswick, other areas in the Maritimes seem to have cases. And I know that in Alberta, where I come from, we've had a whooping cough outbreak since 2022. So we know we have cases out West as well. And just the sheer number this time seems to be so high that if you put all those together, we're at half of the cases that we had been in the last 15 years for this illness.

BRIAN GOLDMAN: That's a lot. Which leads to a very obvious question: why do you think that's happening? And part of the reason you've said is the cyclical nature of pertussis. It comes and it goes, and we seem to be on an upswing right now. But are there other factors at work?

DR. CORA CONSTANTINESCU: There are multiple factors at work. But I almost feel that before I can tell you why I think this is happening -- because there are many factors -- I think we should talk a little bit about vaccination rates. If you were to look at, let's say, uptake of the pertussis vaccine. We have a whooping cough-containing vaccine -- we've had it for, you know, over 70 years. If you were to look at the uptake at the two years of age for the vaccine, we're somewhere around, you know, 74 to 78% across Canada. Now, in Canada, we don't have a national immunization registry and surveillance, so we have very different uptake across country, but also, reporting across the country. In a place like Alberta, where we have a very robust reporting and surveillance system for immunization, and we have a provincial registry and an accessible dashboard, I looked up the rate just before the pandemic. So, around 2018, 2019, we were around 80% uptake. And then in 2022, we were at 74% uptake. So we had dropped...

BRIAN GOLDMAN: Wow.

DR. CORA CONSTANTINESCU: We had dropped over 6%.

BRIAN GOLDMAN: That's a lot.

DR. CORA CONSTANTINESCU: And we didn't even start at an optimal stage. Because you want to be ideally over 90% to have this, you know, magical community protection or herd immunity. So, when you think of that significant vaccination drop over the last few years, you know that that's going to contribute to just having more pockets of unimmunized or under-immunized communities. And we know that that's where the bacterium really likes to spread. So that's one big reason, is our overall vaccination rates have dropped in the last few years. And then the other big contributor to this is that the vaccine itself is quite good at protecting babies, but the immunity wanes as we get older. So as early as adolescence, for example -- sometimes even younger than that, you know, in the 10- to 11-year age group -- we wane immunity. So, the immunity is not as good as it was before. You have this population that might not have had a booster. Most adults don't have a booster, unfortunately, for this, and they spread it for three to four weeks potentially when they do have it. And then you have these really under-immunized or unimmunized communities. [BRIAN: Mm-hmm.] And, of course, we have a lot of movement. We've had a lot of mobility that's happening in terms of travel. So you have this combination of low vaccination rates at baseline, a waning immunity as people get older, and a bacterium that is very good at spreading for weeks and weeks.

BRIAN GOLDMAN: How detrimental is this waning immunity? Do you actually reach a point where you're completely susceptible as if you were never immunized?

DR. CORA CONSTANTINESCU: That's such a great question and [laughs] it's being studied quite a lot. So remember that we immunize because we want to prevent hospitalization and severity. That's why we have immunization programs.

BRIAN GOLDMAN: Right.

DR. CORA CONSTANTINESCU: And this is why when we say the vaccine works really well in the first, you know, two years of life, it's because it keeps babies out of hospital and out of severe territory in terms of this disease. But as we go further away from that last dose -- which usually tends to be around, you know, somewhere around school age -- as early as five to ten years post, we're seeing a drop in immunity. It doesn't mean that we are necessarily ourselves as prone to severity as we might be if we didn't get immunized. But we are enough of a drop to get the disease and therefore spread the disease.

BRIAN GOLDMAN: Mm-hmm.

DR. CORA CONSTANTINESCU: That's the difficult part when people wrap their heads around, you know, saying, well, does the vaccine not work? Well, it does in that age group that we wanted to protect kids out of hospital. But it's not good enough to see us through adolescence and adulthood without a booster, in terms of keeping communities safe from spread.

BRIAN GOLDMAN: What do we know so far about who? What kinds of individuals are getting pertussis or whooping cough in Canada right now? Is it unvaccinated infants? Is it older people? What are we hearing?

DR. CORA CONSTANTINESCU: Most of the cases are in adolescents and in adults. So, for example, the largest age group seems to be that 10- to 14-year age group, which is historically the age group that tends to have the whooping cough outbreaks because of that waning immunity, and because, of course, they're, you know, moving around, doing a lot of things. [BRIAN: Got it.] And they tend to represent a good third of the cases that we know up to date. When you look at who are the ones that end up in hospital, it's going to be those under one year of age. So, it's a little bit different in terms of where you see the disease versus where you see the severity, which is, of course, again, as expected. That is, I would say, very similar to our pre-pandemic pattern. It's because, you know, that's how this disease works. Now, in terms of who is immunized... and remember that we don't really know the denominator very well, because I suspect there are a lot more cases of whooping cough out there. People are just not getting tested.

BRIAN GOLDMAN: Right. Yep.

DR. CORA CONSTANTINESCU: And it's also not super easy to test. As a family physician, for example, you have to have a special pertussis swab. It has to be in a special medium. It's not as easy as sending it in the same swab as, for example, group A strep. [BRIAN: Mm-hmm.] But we know that about 50 to 60% of people who have it, have had some immunization in the past. That, again, speaks to that waning immunity. So it's not that people have not had immunization in that age range where immunization has waned. But when you look at who ends up in hospital, it's the unimmunized or the under-immunized.

BRIAN GOLDMAN: The infants that are getting infected are largely unvaccinated?

DR. CORA CONSTANTINESCU: Remember, we cannot start the vaccination series till about two months of age. And on the first dose of the vaccine, you don't have fantastic protection. You know, maybe somewhere between 40 to 60%. And you train your immune system. So, the more number of doses you get, the better your immune system gets at fighting it. This is why we're seeing that under-six-months-of-age being so vulnerable as an age group. But this is also why we recommend that pregnant people -- so, women and people who are pregnant -- have a pertussis vaccine in somewhere between second and third trimester, so that immunity can be passed via the placenta to that baby in the first three months of life, before they've actually been able to have appropriate pertussis protection through a vaccine of their own. So this is why we try so hard and recommend this vaccine with every pregnancy, so that we can protect the baby in those first few vulnerable months.

BRIAN GOLDMAN: And this would be standard for a pregnant patient receiving prenatal care.

DR. CORA CONSTANTINESCU: Exactly. So since 2019, that accommodation has been there with every pregnancy. We don't look at the time between pregnancies, because this is not for the mom's protection. This is for the baby's protection. And because we know protection wanes, we want it to be as high as possible with each pregnancy to protect that baby.

BRIAN GOLDMAN: You know, this is a bit of an opinion question, but what do you see, if anything, as the relationship between COVID fatigue and lower vaccination rates?

DR. CORA CONSTANTINESCU: Well, I think it's real. Most of my academic time gets spent on vaccine advocacy and, and how to educate people around vaccines better. And I would say that post-COVID, I think health-care workers feel quite disengaged when it comes to vaccine advocacy. And I think our communities are less immunized than ever. So, for sure, I think there is a significant impact there. And we know from public opinion polls that Canadians have lost some confidence in routine immunizations in addition to COVID. And this is why I think... you know, I can't help but get excited that these infectious diseases get coverage in the media, because it just highlights to parents -- and, you know, I'm a parent, too. I have three kids. For them to think, is this in my community and is my kid protected enough? You know, because we know that what changes vaccination behaviour is perceiving a personal threat to your own child. So, that's my message to all parents. Just think, like, is this around me and is my kid protected? And is there something more I can do for them? Especially if that kid is a little baby. And if they're not, you know... you know, I'll tell you the other thing that did come out of the pandemic, which was very interesting to me, is that we found out that teenagers have a really strong sense of collective responsibility. This is what I call the collective responsibility vaccine, right? We want our teenagers and our adults to get immunized so they can protect the babies. So this is not, you know, your own personal protection when you're an adult. It's to-- if you care about communities and if you care about keeping babies out of hospital. And I have met so many teenagers who have been very keen on saying, what can I do? Is there something I can do to protect others around me? And I do think that is a little bit of a, you know, maybe the silver lining of the pandemic, is that it has made other people think about this more. And I'm, I'm hopeful that this will continue because we're dependent on other people's behaviour to protect these vulnerable babies.

BRIAN GOLDMAN: I certainly share your hope. A reminder that the germ that causes pertussis is a bacterium, which means it's susceptible to antibiotics. And I wanted to ask you, how effective are antibiotics in treating the disease?

DR. CORA CONSTANTINESCU: We have treatment options, but we don't have a cure for whooping cough. So, we do have a whole class of antibiotics called macrolides that we can use to treat this disease. But what they're really good at is preventing spread. So if you have it and you have the antibiotic course, then you're a lot less likely to spread it in community. So they're an important tool to prevent further spread. But once the inflammation cascade has been started in the respiratory system and the toxin has been released, we don't really have something that's really good to treat that. So, that's where you end up needing that tertiary level of care where you need, you know, intubation, you need life-saving equipment and staff who can do this. Because there is nothing that we know that works well at stopping that cascade of inflammation and the effect of that toxin. And I, a little bit tongue in cheek and a little bit, you know, feeling hopeless about this, I say, this is the kitchen sink, the proverbial kitchen sink situation where, you know, when we have a case of whooping cough in the ICU, and the baby's intubated and the pressure in the lungs is going up, you know, you have people come together, and then we pull all kinds of what we hope is going to make a different treatment, but that we know they really have not been shown to be of huge benefit. So this is the problem, is that the antibiotics work at preventing spread and they are a good option for treatment, but we don't actually have a cure for the severe version of this disease.

BRIAN GOLDMAN: Clearly, the provinces and public health units have a big job, in the case of outbreaks, to trace contacts. What else are they doing to try and boost vaccination rates?

DR. CORA CONSTANTINESCU: We know there are some things that really help, particularly when you think of vaccine uptake. You know, people talk about convenience, confidence and complacency. So I think the big aspect is convenience. So, can you help remind people. And we know that-- I know at least for sure in Alberta they've done a lot of work to try and send text reminders and email reminders. And they have gone-- finding-- We, we have such a good vaccine registry that we can find people who are unimmunized and remind parents that their child is due for an immunization. And that has actually been shown to make a real difference -- when you can actually make it easier to remind parents. And then I think what would be a real help is to increase convenience. So, if we could have the vaccine more available and accessible, for example, in pharmacies. Now we know that, you know, in Alberta, come February 2025, pharmacies can vaccinate as early as two years of age. You know, as a parent, being able to just have a walk-in appointment, being able to have an appointment quickly available, that makes a difference to vaccine uptake. And they've tried to catch up children by changing the immunization schedule a bit. So, this is not an example for whooping cough, but it is for the measles, mumps, rubella, varicella vaccine. For example, in Alberta, they've moved from five years to doing it at 18 months, again, to try and bring kids up in immunization uptake so that we can-- looking ahead, we can prevent outbreaks from happening, and also protect those children sooner. And I see the other thing that really helps is this idea of complacency, right? So, think, is this in my community? Is this a threat to my child? And I think that can also help. And I would like to see public health do more of that, where we are more transparent about the number of cases we're seeing, how many children are in hospital. Are we seeing deaths from this disease yet? Because I think that helps build the case for parents appreciating that this is a real threat for their children.

BRIAN GOLDMAN: And just to bring it to a personal level, as a final question, what is the risk if we are, all of us as a society, too complacent when it comes to pertussis?

DR. CORA CONSTANTINESCU: Well, we're going to see more babies in hospital and more babies dying. You know, in pediatrics, we are very protective of our population that we serve. And I would say no child should die of pertussis. That should be the aim in our country. And we still have somewhere between one to four deaths every year. So if we, if we don't, then we're going to spread this, and then we're going to see more babies having bad outcomes.

BRIAN GOLDMAN: Well, that's a timely reminder of outbreaks taking place across Canada that are a cause for concern. Dr. Cora Constantinescu, thank you so much for bringing this important topic to us on The Dose.

DR. CORA CONSTANTINESCU: Thank you so much for having me and for bringing attention to this.

BRIAN GOLDMAN: Dr. Cora Constantinescu is a pediatrician, infectious diseases specialist and clinical associate professor at the University of Calgary's Cumming School of Medicine. Here's your dose of smart advice: Cases of whooping cough are up in many parts of Canada, including Ontario, Quebec and New Brunswick. Authorities in other provinces like Nova Scotia say a spike in cases is a matter of when, not if. Whooping cough, also known as pertussis, is a bacterial infection that spreads through coughs or sneezes from someone who's infected. The initial symptoms include runny nose, sneezing, mild fever and cough. The cough gets worse over one to two weeks, turning into those rapid-fire bursts of staccato coughing that leave patients little time to breathe. The sharp intake of air, which sounds like a 'whoop,' gives the disease its name. A person with whooping cough can pass it on to others as soon as they get cold-like symptoms. They can also pass it for up to three weeks after they start coughing. The incidence of whooping cough is on the rise, in part because of falling vaccination rates, and from waning immunity in adolescents and young adults who don't have their booster shots. The incidence of pertussis tends to be cyclical as well, with infections peaking at two to five-year intervals. You can contract whooping cough at any age. The symptoms tend to be milder for adolescents and adults. The risk is greatest in infants under one year of age. That's because routine pertussis vaccinations begin at two months of age, thus, the kids at risk for the disease are unvaccinated or have yet to complete a full series of immunizations. The complications of whooping cough, which are more common in infants and young children, include pneumonia, middle ear infections, dehydration, seizures, a brain disorder known as encephalopathy, and death. The most important thing you can do to protect your kids is to make sure they're up to date on their vaccines. Children under the age of six need five doses -- at two, four, six and 18 months of age, plus another dose between the ages of four and six years. Teens generally need a booster sometime between 14 and 16 years of age, and adults may need a booster if they're around infants at risk. Since 2019, experts have also recommended that pregnant women receive a booster called Tdap -- tetanus, diphtheria and pertussis -- early in their third trimester to protect their babies after they're born. Antibiotics help prevent patients with whooping cough from spreading it to others, but are not good at curing the disease once the coughing begins. Stemming outbreaks in adolescents and young adults through vaccination programs is essential to protecting young infants who are at the greatest risk of severe illness and death. 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 listen. 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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What do I need to know about whooping cough? - Transcript

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