Front Burner - Rare COVID-19 vaccine blood clots explained

Episode Date: April 30, 2021

With the news that a woman in Quebec died of a rare blood clot after receiving the AstraZeneca-Oxford COVID-19 vaccine, some people may feel concerned about the vaccine. Epidemiologist Maria Sundaram unpacks what you need to know about these extremely rare blood clots and the COVID-19 vaccines.

In the Dragon's Den, a simple pitch can lead to a life-changing connection. Watch new episodes of Dragon's Den free on CBC Gem. Brought to you in part by National Angel Capital Organization, empowering Canada's entrepreneurs through angel investment and industry connections. This is a CBC Podcast. Yeah, so they're incredibly rare and they get rarer as you get older. That's Maria Sundaram. You might have heard her on the show before. She's an infectious disease epidemiologist who studies vaccines.

Earlier this week, it was announced that a 54-year-old woman in Quebec died of a rare blood clot after receiving her AstraZeneca shot. And I get that headlines like that, they can make people nervous. So I wanted to bring Maria back to talk through what you need to know about coronavirus vaccines and these extremely rare blood clots. Hi, Maria. Thank you so much for coming back onto the podcast. It's really my pleasure. Thanks for having me. So what's the first thing you would say to someone who's feeling uneasy about the AstraZeneca vaccine after reading the various headlines about these rare blood clots? I think the first thing I would say is I totally understand

why you feel that way. It makes sense. And it's really hard, I think, with all of this information floating around and some of it sounding very, very scary for us to really put all of these risks into context. And so that's what I'm hoping to help with today. And I wonder if we can start by putting some of these numbers into context. So can you give me a sense of just how rare these blood clots are? What kinds of numbers do we have on this? Yeah, so they're incredibly rare, and they get rarer as you get older. So for example, someone who's in the 20 to 29 year range, their risk is perhaps one in about 100,000 for the AstraZeneca vaccine, at least as far as we know right now, although the events again are quite, quite rare. And then for example, people who are 50 and up, their risk is about 0.3 in 100,000, so quite rare. Why is it that people

who are younger have a greater risk, even though it's still small? This is a little bit tough to tell, and it's specifically tough to tell because we know that these vaccines, some of them have been kind of directed towards younger people who are healthcare workers and or teachers or other essential workers. So it's a little bit challenging to identify if this is kind of an epidemiological artifact or if it's truly a novel, like real finding, but that's still being investigated. Okay. And just to be clear here, you know, we're talking about the AstraZeneca vaccine, but there are, or there is another vaccine that is also linked to these very rare blood clots, right? Yeah. So there's another adenovirus factor vaccine, which is the same

type of vaccine that the AstraZeneca vaccine is. And it's manufactured by Johnson and Johnson. That vaccine is approved for use in Canada, but there aren't currently those vaccines in Canada yet. But those vaccines are available in the US. And... Right. And I actually believe just a bit of news on that front that we got our first shipment this week of the Johnson & Johnson vaccines. Oh, well, that's wonderful. That's great news. So look, I do understand that, and correct me if I'm wrong here, but the likelihood of getting a blood clot from contracting COVID-19 is actually much higher than getting a blood clot from one of these vaccines. Oh, yes. Yeah, we've seen estimates of blood clots in COVID-19 patients all the way from one in 200,

which is already quite a bit more common than we're seeing with the AstraZeneca vaccine or the J&J vaccine, all the way to one in three people who might be in the ICU for COVID-19 having a blood clot. So this is also something that's very, very serious that we have to weigh sort of in conjunction with the vaccine as well. But I guess my question to that is, is it the same kind of blood clot that people are getting with COVID-19 compared to the kind of blood clot that they're getting after these vaccines? It is not the same kind of blood clot. And that's a really important thing to bring up. And I think, you know, one of the most common things that we talk about is, you know, we're kind of putting this in terms of risk of other blood clots. But this particular type of blood clot that's happening, that we're seeing happen in very rare cases after

these vaccines is a really unusual type of blood clot. And can you tell me more about what kind of blood clot it is? Yeah, absolutely. So normally when our blood clots, it uses things called platelets to do that. And what's really unusual about the blood clots that are happening in these very rare cases is that people have these blood clots and then simultaneously they have very low levels of platelets. So this is really unusual and it's also helping us to identify this very rare outcome because it's, again, it is so unusual. Are these blood clots more dangerous? Do they do something different in your body than, you know, other kinds of blood clots? Well, they're not necessarily more dangerous than other types of blood clots, but I think

there is a really important component there for providers, medical providers and clinicians. Because people have low platelets in conjunction with these blood clots, they shouldn't be put on a blood thinner like heparin. What do we know about what's actually the cause of it, the cause of the clots? So there are a couple of hypotheses that we're currently testing. One of them is that the free DNA, which is inside of the adenovirus factor that we get in the vaccine, it's negatively charged. It could potentially attach to this complex of heparin and something called platelet factor 4, and that could kind of involve our immune system to react against platelets and cause these blood clots. And there's another sort of related

potential explanation where we have this kind of what's called peripheral tolerance. And this is kind of a way for our immune system to say, hey, don't attack that. That's us. We need those cells. We made them. So please don't act like they're a foreign pathogen. So we have those checks all the time. Perhaps those checks could be slightly disrupted with this type of vaccine. So that's something that's also being looked into. I have seen reports of these very rare blood clots, like essentially being in people's brains. And I think that might scare people. And I wonder if you could shed some light on that. Yeah, absolutely. And yeah, I think it is, it's quite scary. The idea of a blood clot in your brain is very scary.

clot in your brain is very scary. I think what's perhaps important to try to remember is that these types of blood clots don't occur only in the brain, although we have seen them occur in the brain in some cases. And another important thing to remember is that other blood clots can also occur in the brain, including those blood clots that you might get, for example, if you get COVID-19. Okay. And you mentioned, you know, that because of the low platelets that these blood clots can be identified. And so can you talk to me a little bit more about that, like how people might be able to identify this risk themselves and how doctors can go about identifying this small, small risk? The first thing probably to know is that even if you think that you might be at increased risk of blood clots in general, or if you've been told by a doctor that you might be at increased risk for blood clots in general, that doesn't really mean anything with regard to your risk of this very rare outcome. So, for example, if you feel as though you're at increased risk

for blood clots sort of in general, you don't need to worry specifically about this vaccine in that context. That being said, if for example, 4 to 15 or 4 to 20 days after you take the AstraZeneca vaccine or the Johnson & Johnson vaccine, and you have some symptoms of blood clots, you should let your doctor know right away. And these symptoms include things like a persistent headache that won't go away, lower leg swelling, blurred vision, dizziness, nausea, vomiting, and then kind of neurological symptoms like tingling or numbness in your limbs. But again, these kinds of symptoms are, hopefully it's kind of obvious, like they're quite, quite rare.

And the outcomes that they're associated with are also quite, quite rare. You mentioned that if you have like a predisposition for blood clots, that it's not related to these blood clots. I've also heard people talk about, you know, women who are on contraception, like the birth control pill, or people who might be smokers. Do they have a higher risk of getting this rare

blood clot from a vaccine? Right now, it doesn't appear that either smoking or being on oral contraceptives increases your risk of this particular very rare blood clot. Hi, it's Ramit Sethi here. in part by National Angel Capital Organization, empowering Canada's entrepreneurs through angel investment and industry connections. Hi, it's Ramit Sethi here. You may have seen my money show on Netflix. I've been talking about money for 20 years. I've talked to millions of people and I have some startling numbers to share with you. Did you know that of the people I speak to, 50% of them do not know their own household income. That's not a typo. 50%. That's because money is confusing.

In my new book and podcast, Money for Couples, I help you and your partner create a financial vision together. To listen to this podcast, just search for Money for Couples. I'm sure for a lot of our listeners, they will be delighted to get whatever vaccine they've been offered whenever they're offered it. But for those who might be feeling a little bit more hesitant about AstraZeneca or Johnson and Johnson, is there anything else you think a person should know so that they can feel informed before making a decision about getting the shot?

Yeah, so when I've been thinking about this over the last couple of weeks, I was actually thinking about a conversation that I had with a doctor a while ago when at an earlier point in my life, I decided to go on oral contraceptives. And during that conversation, my doctor sat down with me and she said, you know, this is great that you know, that you want to take this step. And, you know, I have to tell you that there is a potentially increased risk of blood clot while you're on oral contraceptives. And she helped me kind of understand what was the potential risk of this rare outcome. And then what was the potential benefit to me of being

on oral contraceptives, including the fact that blood clots might be more common if I were to get pregnant than if I were on oral contraceptives. And so that conversation with her really did help me understand, okay, these are the risks and these are the benefits. And this is like a risk-benefit calculation that I feel really comfortable with. And when I compare and contrast that with what's happening sort of epidemiologically in Canada, it really kind of draws a lot of very strong parallels for me. So, you know, the circulation of COVID-19 in Canada right now, as we all know, it's kind of, it's a little bit higher than we certainly want it to be. So it's about 180 cases per 100,000 in Ontario. And in Toronto, in particular, it's 250 per 100,000.

So that is definitely a high exposure risk zone. So that means if you're 20 to 29 years old, and you're living in Toronto, you have a risk of ICU admission due to COVID-19 every 16 weeks of about seven per 100,000. Conversely, your risk of the blood clot is about one per 100,000. And so and that kind of that risk of ICU admission goes up with age and the risk of blood clot goes down with age. And so we're kind of seeing like the risk benefit calculation get better and better and better, the older you get. That was some really helpful number crunching there. Listening to you talk about the decisions you made around contraception, it also makes me think of a conversation that I had maybe last year with my

midwife when I was pregnant about whether or not I was going to get on an airplane, because that does also slightly raise your chances of getting blood clots. And, you know, long story short, similarly, by the end of the conversation, I had also made the decision to get on an airplane. I had also made the decision to get on an airplane. Just continuing on what you were just saying about, you know, the risks of contracting COVID and the risks of being in an ICU, what might you say to somebody in Atlantic Canada, where up until recently, there was barely any risk of community spread. So might that be something worth weighing if you don't live in Toronto or Brampton or Calgary, for example? Yeah, I think that's really, really important. Because when we're talking about risk benefit, we also have to talk about

the risk, the risk of COVID. And the risk of COVID, for example, in Newfoundland and Labrador right now is three per 100,000. So that's really incredible. First of all, I think it really speaks to a dedication to having zero COVID, which has been really strongly supported by public health infrastructure. And that's amazing. But that means, yeah, you have a different sort of potential benefit from this vaccine because you have a different risk of potential benefit from this vaccine because you have a different risk of exposure. That being said, personally speaking, I, you know, I, I have seen how quickly the pandemic can really take a turn for the worse in areas that, that have low transmission, community transmission, even a few months before that. And so my sort of personal take on this is that, you know, I want everyone to be as protected as possible, as quickly as

possible. But this is, I think you bring up a very important point about individual sort of risk benefit calculations and how, you know, in the Atlantic provinces, you know, that might be a different calculation. We talked earlier about the symptoms that a person would want to look for to try and identify these very rare clots. I do want to be very clear about one thing. These are very treatable, right? That's right. So they can have very severe outcomes if they're not treated. They do need to be treated very quickly when they sort of have an onset.

When you notice, for example, your headache hasn't gone away or you you're having like a leg swelling, you do need to seek care right away. But if you do, it's very treatable, and you're going to recover. You know, we've talked about what to watch out for here and to go and seek treatment. But just generally, when a person does get their shot, what kinds of normal side effects should they be prepared for? Should they be expecting? It really does seem like it's hitting everyone slightly differently. And even among my friends and family, I've heard a broad range of experiences. Both my parents got it and they both were like, I didn't feel anything. I feel completely fine and I don't notice anything at all. And that's wonderful. My little sister, who's a healthcare provider, said that she had a mild low-grade fever for about a day and a half. And then she also had

some joint pain. Other friends have noted a minor kind of muscle achy, what my mom would call just kind of cruddy feeling. It usually goes away after a day and a half or so. Right. I've heard people kind of describe it as like a bit of a hangover. Maria, I'd love to get your thoughts on this before we go today. I think sometimes it can be hard to talk about these issues and it can be so easy to get alarmed when you hear someone has died from purportedly a vaccine. And I have to be honest, I was reticent about even doing this episode because I don't want to contribute in any way to outsized concern. Though at the same time, I also believe people don't need to be protected from good quality information. So it was a bit of a struggle. And I wonder if I could get your

thoughts here. How do we find the balance of making space to talk about issues like this without blowing things out of proportion? It's always been my perspective that talking about things rarely makes them worse, especially if people are scared and they have questions. I have the privilege of a long education in vaccine epidemiology and vaccine safety. So it's maybe easier for me to sit down and look at this risk benefit and say, okay, I feel very comfortable with this. I keep thinking if this were like a pandemic where I needed to know a lot about like art history or something, I would be completely lost. And I would feel a lot more unsure because I wouldn't feel as though I had personal experience that informed my decision making.

So I do think it's really wonderful that we talk empathetically and carefully about these things rather than sort of saying, well, you know, don't worry about it. It's fine. Don't ask any more questions because, you know, this is, I think, really where the rubber hits the road in terms of people developing trust, understanding the process, and feeling okay about the decisions they make. Okay. Maria, thank you, as always, for being here. I really, really appreciate it. It's my pleasure. It's my pleasure. All right, so before we say goodbye, more news on the ongoing crisis inside the armed forces. Along with the recent allegations of misconduct facing senior leaders, including the last two chief of defense staff, Chief of Defence Staff. New information tabled in Parliament this week revealed that 581 reports of sexual assault and 221 incidents of sexual harassment in the Canadian military were made

over the last five years alone. The reports were made during Operation Honour, the last military effort to stop sexual misconduct in the ranks. In related news, on Thursday, Defense Minister Harjit Sajjan announced the launch of another independent external review led by former Supreme Court Justice Louise Arbor. This is the second one in just six years. The review will look into sexual misconduct in the military and offer a framework for an independent system of allegations to be reported outside the chain of command. And just so you know, for weeks, FrontBurner has been renewing a long-standing request to speak with Minister Sajjan. All right, as always, FrontBurner is brought to you by CBC News and CBC Podcasts.

The show is produced this week by Imogen Burchard, Shannon Higgins, Derek Vanderwyk, Allie Janes, Ashley Fraser, and Tatiana Furtado. Our sound design was by Austin Pomeroy, Julia Whitman, and Mackenzie Cameron. Our music is by Joseph Shabison of Boombox Sound. The executive producer of Front Burner is Nick McKay-Blocos, and I'm Jamie Poisson. Thanks so much for listening. We'll talk to you on Monday.