A look at the science behind vaccines and blood clots

[00:00:00] Jordan Heath-Rawlings: Be honest with me. If I asked you, “What are the first things that come to mind when you think of the AstraZeneca vaccine for COVID-19?” Would blood clots be high on that list? Regardless of your own answer, statistically speaking, you know some people who would turn down this life-saving vaccine right now. If it were offered to them, and the risk of a blood clot issue would be one of the things they would cite to explain that decision.

Is this a failure of public health communications? A failure of the media, including us, in continually covering it? Or an example of a real issue that we need to learn more about? The answer probably is all three. The risk of a blood clotting issue from this vaccine is vanishingly small. But that doesn’t mean that it’s not worth discussing, especially if the [00:01:00] discussion can move beyond, “Should I still get it?” Because obviously yes, you should, and move towards what is actually happening in the bodies of people who experienced this. What can it teach us about how our immune systems respond both to the vaccines and the COVID-19 virus itself. As you may know, there is a lot of misinformation associated with vaccines and with the risks of blood clots from this vaccine in particular.

But there is also a lot of science here that’s worth diving into so that you can put the risks into context, but also so that we can all understand better the kind of incredible discoveries we’re making every day during this pandemic.

I’m Jordan Heath-Rawlings, this is The Big Story. Roxanne Khamsi is an independent science journalist who dove deep into the [00:02:00] AstraZeneca and Johnson & Johnson blood clotting issue for the Atlantic. Hey Roxanne.

Roxanne Khamsi: How’s it going?

Jordan Heath-Rawlings: It’s going well. I’m, uh, I’m excited to talk about this because I feel like this is a way more complex, uh, medical issue than it’s often presented as, is that accurate?

Roxanne Khamsi: Oh, I mean, absolutely. I think that with each day that goes by a new layer is added and the average person’s kind of just left, scratching their head and thinking like, what does this mean for me? But absolutely the science is, is, is getting deeper by the day.

And it’s, it’s great in a way, because we’re learning so much about vaccines that we never knew.

Jordan Heath-Rawlings: Maybe let’s, uh, frame the discussion to start. When people are talking about the blood clot issue with the AstraZeneca and also, uh, the Johnson & Johnson vaccines, what are they referring to?

Roxanne Khamsi: So, you know, with any vaccine there’s going to be side effects. And, um, sometimes those side effects don’t really show up necessarily in a clinical trial, or they show [00:03:00] up, but they don’t really seem like a strong signal because it hasn’t been given to a lot of people. And what happened is that, um, as these vaccines were rolled out, and both the AstraZeneca and Johnson & Johnson vaccines use what’s known as an adenovirus, which is like a, a vector that is used to package the thing that they want to immunize us with.

And it’s a totally safe, uh, non-replicating virus that does that. But what they noticed as this was rolled out to folks, was that, um, it, it worked very well, you know. A hundred percent of hospitalizations and, and, uh, critical cases were prevented in the, in the trial. So this is like a good- these are good vaccines.

But, uh, unfortunately there was a curious few small handful of cases where people developed a very, very strange form of blood clotting.

Jordan Heath-Rawlings: When you say a very, very small number of cases, what do we know about the actual scope of this problem? As, um, you know, we first heard about [00:04:00] this a couple of months ago, and now, you know, AstraZeneca’s everywhere in Canada, Johnson & Johnson, uh, was being used in the States before it was paused. What is the scope of it? And is it changing?

Roxanne Khamsi: Yeah. So that’s a great question. And, um, you know, in Canada, last I checked in the numbers do change, but like there were just three cases with, uh, with a fourth in New Brunswick added of this clotting event. And what’s, what’s unusual about this kind of blood abnormality is there’s both clotting, but there’s also kind of a lack of platelets in the blood, which is a kind of a thing that’s used for clotting.

So, you know, it’s a very unusual combination of events that happen together. We have the best data so far, I think, from Europe in terms of the scope of this problem, and the numbers there again are really, really small. So with AstraZeneca, they’ve got 142 in 16 million doses given, uh, of this kind of clotting event, um, and then, you know, other numbers for other vaccines. But this it’s just, [00:05:00] when you consider how many arms these shots are going into, this is highly, highly unusual and high- and highly, highly rare, is the word, I guess I would emphasize.

So, you know, this is a life saving vaccine that works really, really well. And it really, um, shouldn’t scare too- people too much from, from getting vaccinated with them.

Jordan Heath-Rawlings: If that’s the case, um, and maybe I’m defeating the purpose of my own podcast here, but if that’s the case, why are we spending so much time talking about these really small numbers?

Roxanne Khamsi: Well, I think the key is that, um, scientists kind of want to get a better sense of if we can figure out who might be predisposed to this kind of complication, uh, rare side effect. And that’s really hard because there’s so few cases.

But I think that, you know, in addition that there is an echo of, of the clotting issues that happen in COVID itself. So I think a lot of scientists are trying to figure out, is there some connection? I mean, as you know, I’m sure, like, one of the reasons that COVID [00:06:00] itself is so dangerous, one of the reasons we have to get vaccinated is that there are these strange clotting events that happen in COVID itself.

So I think some of the incentive is to understand if there’s some sort of connection between those things, and also to kind of reassure the public that, you know, even though these things are rare, we have the powerful tools in science to get, get a, get a better grip on what’s going on.

Jordan Heath-Rawlings: I want to get into the actual science of this with you, because that’s what your piece in the Atlantic was about, and it went deeper than anything I’ve, I’ve seen on this stuff so far. So you might have to explain some things to me like I’m five, um, but maybe, maybe we’ll just start with, you know, you mentioned that these are really strange clotting issues and. How were they different, um, from regular blood clots, which we’ve seen discussed in relation to this, right? In terms of women who have been on birth control, and their risk of blood clots.

Roxanne Khamsi: You know, one of the things that was interesting to me as I reported the story for the Atlantic was that not all clotting events are the same [00:07:00] and, uh, you know, like. So, there are different names, even,, there’s thrombosis, there’s thrombocytopenia, there’s all these kinds of big words that doctors throw around.

Uh, but at the end of the day, one thing that a doctor told me that was super useful is, if you kind of think about the clotting system like bricks and mortar. And so, um, when you’re forming a clot, you’ve got these platelets forming a wall, if you want, or something to stop you from bleeding when you don’t want it to be bleeding. And then you have these other factors in your blood that help act as the mortar and kind of put them together. Um, so a clot is when you have, like, let’s say a brick wall in the wrong place and it’s too big. Um, but then there’s also situations where you’re building so many walls in your body with these bricks that you’re running low on bricks for normal things, which is what this thrombocytopenia is.

And usually you don’t have both of those things, um, happening at the same time. But in these rare cases of the side effects with the, [00:08:00] the AstraZeneca- AstraZeneca vaccine, and to some extent, Johnson & Johnson, they’re seeing this kind of problem where you’re running low on blood platelets, but you’re also building a lot of clots, and that’s the puzzle that scientists are trying to figure out.

Jordan Heath-Rawlings: How dangerous are they? Are they more dangerous than regular blood clots? What’s the treatment for them?

Roxanne Khamsi: Well, in terms of the danger, I think, like, with anything in medicine, it kind of comes down to the person who’s experiencing it and the individual situation. I don’t think that there is a, a. I mean, part of it is we’re trying to just get a scope of the clotting issues as well. I’ve seen doctors characterizing different manifestations of these clots in patients, in different parts of the body. So I don’t know if there’s enough uniformity of data right now to know about whether these clots are more dangerous than say, the clots you hear about people getting in other scenarios, you know, where they get rushed to the hospital.

Um, I guess what you could say is like. Generally [00:09:00] clots that aren’t helping your body stop bleeding are not great. Like even you can get one flying on a plane somewhere, sometimes, you know, like deep vein thrombosis, which is a way to say, like, you know, clot you sometimes in your leg. Um, but your second part of your question was super important, which was, you know, what does it mean for the treatment of these clots?

And not to get all into the science, but there is some inkling that these clots resemble what’s known as Heparin-induced thrombocytopenia, a condition where your body makes these antibodies against the drug Heparin, and accidentally starts erasing your platelets from your blood as well. Um, and so there are some hesitations, since this clotting event kind of looks like that.

There’s a hesitation to give these patients, some of whom didn’t have Heparin, and many of, you know, a lot of them just didn’t have Heparin at all before they got symptoms. There’s hesitation to give them Heparin since it looks like that other disorder. They’re worried, it’s going to kind of [00:10:00] push it more in that direction. But I’ve seen scientists questioning that as well.

So we just don’t really know fully the treatment implications.

Jordan Heath-Rawlings: I guess what I want to know next is how do we go about figuring out what could be causing this? Like, do we have theories as to why this is happening with these vaccines?

Roxanne Khamsi: Yeah, so there’s like four-ish theories, and they have some overlap with each other.

Um, One of the theories, which has kind of gotten a lot of momentum behind it is that, you know, we, the, the, the people that have these rare side effects somehow are forming, like, the wrong kind of antibodies. You know, like we’re always talking about how great the antibodies are that these vaccines cause us to produce and they are fantastic, but there’s a question, or, or, they found, actually, in these people that have this rare clotting event, um, a really unusual antibody against something that their platelets make, which [00:11:00] kind of builds into this whole story of like how this might be going on. Um, but you know, this is very early-stage science, so we don’t know if it actually explains it. It’s just kinda, it is really just a hypothesis at this time.

Um, and again, I want to say this is a really, really, really rare thing. Um, and you know, what’s not rare is getting COVID. COVID is highly contagious. It’s very deadly. Um, when we’re, we’re, uh- the human brain isn’t great about thinking about risk. So I just kind of want to come back every time to say, uh, you know, we, we, we, you and I can talk about all these theories behind these rare events, but, uh, what was, what is not theoretical is the danger of COVID.

Jordan Heath-Rawlings: And for what it’s worth to anybody listening, I got the AstraZeneca vaccine, you should too. Um, you know, public service announcement time. What are the other theories?

Roxanne Khamsi: So the other theories, um, one of which I find really intriguing is that the spike protein might be kind of in the wrong place and doing the wrong thing just [00:12:00] accidentally. Um, and that it might be disturbing platelets and disturbing the blood vessel cells, um, which to me is intriguing because it kind of ties in with like how COVID itself, which for sure causes, you know, bad clotting events that are fatal, might be doing that, that awful thing.

You know, there’s totally not a lot of agreement on this stuff. So it’s very TBD, to be determined.

Jordan Heath-Rawlings: Well, how do, um, scientists and doctors and health professionals kind of walk the line, I guess, between discussing this like, like you and I are doing, um, and trying to get to the bottom of it and trying to figure it out, you know, how much of this is related to COVID and related to the vaccine? How do you balance that in-depth discovery with, you know, the stuff we’ve also talked about that can cause vaccine hesitancy, right? Like it’s, it’s kind of a trade off. The more you talk about it, the more it’s out there.

Roxanne Khamsi: Absolutely. I think [00:13:00] that, um, what I’ve really been encouraged by is all the transparency. Like, you know, they don’t always, um, it’s not easy as a scientist to talk about these rare side effects, because you do worry about what you’re mentioning. And it is easy for the public to forget that we’re talking about, like, dozens of people out of like millions and millions and millions.

Uh, so we get kind of caught up in this because it’s new and it’s new science, but at the end of the day, like, as you say, you got the vaccine and you know, that’s great because now you’re, you’re way more protected than you would be without it. So, um, I kind of remember an email that a scientist sent me. I didn’t have a chance to include it in the Atlantic piece, but he said, you know, this is like getting stung by a bumblebee and having an anaphylactic reaction to that. Uh, it’s not, it shouldn’t stop people from sitting in a beautiful pasture and enjoying a sunny day.

So, you know, that’s kind of something I think about like, you know, it’s important to know, you know, what causes people to react to a [00:14:00] bee sting if it doesn’t, uh, you know, if it’s dangerous for them, but, uh, you know, we still go outside and we still do things that are good for us.

Jordan Heath-Rawlings: I know you don’t want to talk about all the forms of misinformation out there, um, probably because there’s a million of them, but there is one thing, especially with AstraZeneca, especially around the clotting issue that has been popping up on people’s wellness Instagrams, and that’s that the vaccine can change your menstrual cycle and could even impact the menstrual cycle, somehow, I guess, of, of women who are around people who have been vaccinated. And, you know, I, I’m assuming the science says no one that, but I thought I would ask you to clear it up.

Roxanne Khamsi: Well, I think, I’m always looking for the positive Jordan. Like I’m always looking for something that is-

Jordan Heath-Rawlings: It’s been quite a year for you then.

Roxanne Khamsi: I think it’s the only way I’ve survived. So I’m really glad we’re talking about periods, menstruation, all that stuff. Like more power to us for, like, putting that more in the [00:15:00] forefront because we often push it aside. Um, so I think that’s good that people are talking about it.

I don’t think it’s great that people are running with this in directions where we just, I mean, frankly seem ridiculous. Um, and, uh, no, if you’re around somebody who’s gotten vaccinated, it’s not gonna change your menstrual cycle.

There is, you know, any, as many people with a uterus know, like, stress can affect this. And so, and, and who’s to say this pandemic or getting vaccinated or booking that appointment and getting there and the rush, like all those emotions might not affect your cycle? And also menstruation is, in some part, a immunological event. And so, when your body is building that endometrium, which is the lining of your uterus, which it sheds during your period, um, you know, that’s all got like immune cells in there and whatnot.

So. The fact that getting a vaccine might affect your cycle, it’s not impossible, [00:16:00] right? And I think one of the things that’s good is that we’re now talking about why weren’t they, why don’t clinical trials ask about menstruation and, like, changes, because they don’t. But at the end of the day, I mean, when it comes to issues of vaccination, vaccination, and fertility and all that stuff, the things that we do know are that these vaccines are so powerful in protecting pregnant women, protecting their babies. I mean, women that get vaccinated, I just, you know, was reading about how, uh, the babies born to women that are vaccinated have antibodies against COVID. I mean, like you really couldn’t ask for a better outcome than that.

So I think that, um, people that menstruate should be assured that like, this is a safe vaccine, this is a good vaccine. And you know, it doesn’t mean we shouldn’t study this stuff, but let’s not get too carried away with the misinformation.

Jordan Heath-Rawlings: How will we figure this out, uh, going forward? You know, assuming we will, where do we get to the bottom of this and, and what happens next? Do we just need to [00:17:00] wait, uh, sadly enough for more cases of this clotting to pop up?

Roxanne Khamsi: Well, it’s, it’s so interesting that you asked that question because I was asking that question to myself as I was reporting this story, and I kind of got to the end and I wondered if we would really know, um, I mean, on the one hand we still have people debating.

There was a rare side effect, uh, that was proposed to a flu vaccine that was used in that swine flu pandemic, I don’t know if you remember back in 2009. And there was, it wasn’t ever widely available, but in parts of Europe, there was a vaccine called Pandemrix, and in, like, Finland and Sweden, there was some idea that it might be linked to narcolepsy as a side effect. But then, you know, the drug maker decided not to, kind of, keep making the vaccine because there were those concerns. But to this day, there’s still some debate about whether that actually was a real signal, and whether it really was causally linked. You know, causality is the thing that [00:18:00] scientists have to prove, is that like, it’s not just a baseline rate of this kind of thing happening in the normal population.

Um, you know, you might get, you might have, you got your vaccine this week, you might stub your toe and say, “Hey, is that vaccine that I got related to me stubbing my toe?” Uh, so that that’s something that they have to figure out. So anyway, we’re still kind of. Not really settled on that and it’s been 12 years.

So I wonder, you know, how, how are we, how are we going to solve the mystery here? On the one hand, it could take years. On the other hand, we’ve never seen what we’re seeing now, which is just an unprecedented coordinated, um, you know, vigorous analysis, open analysis, transparent- we’re in an information age now. So I kind of have some hope that we’ll actually know a lot more about this sooner rather than later.

Jordan Heath-Rawlings: That’s another thing I wanted to ask you about is, you know, just how much we’re learning, how quickly about, uh, both these vaccines, for sure, but also about COVID [00:19:00] itself, uh, from this issue? And, you know, what is the potential for discovery here?

Roxanne Khamsi: I think it’s huge. I think that the, I mean, I’ve just heard scientists say, I’ve never worked this hard in my life. And you know, if you’ve ever met a scientist, they’re really hardworking people spending hours at the lab, anyway. So I mean, I think just by pure, um, people power, and the hours they’re putting in and the conversations happening, even on social media, between scientists, like, uh, I think that we’re seeing something totally unprecedented, and it’s super encouraging.

And you know, that’s also the same, uh, unprecedented scientific activity that gave us these very good vaccines in the first place, these life-saving vaccines in the first place. So, I mean, I think you kind of alluded to it, but like, the more people that get vaccinated, the closer we are to kind of coming back to what was a semblance of our life before this pandemic.

[00:20:00] And it’s heartbreaking to hear about, the, the, the growing pandemic, uh, both in places in Canada and also, uh, you know, places like India now, or Brazil, where, you know, we hoped that we wouldn’t be at the place we’re at right now, but I really do believe that all these vaccines are going to get us closer to a better place.

Jordan Heath-Rawlings: Roxanne, thank you so much for taking the time to explain this to us.

Roxanne Khamsi: Thank you, Jordan. It’s always good to talk with you.

Jordan Heath-Rawlings: Roxanne Khamsi is an independent science journalist, and that was The Big Story. For more from us, head to thebigstorypodcast.ca. You can find us on Twitter at @TheBigStoryFPN. You can email us, thebigstorypodcast, all one word, all lowercase, @rci.rogers.com [click here!]. And as always, find us in your favourite podcast player, Apple, or Google, or Stitcher, or Spotify, or ask your personal assistant to play The Big Story Podcast.

Thanks for listening. I’m Jordan Heath-Rawlings, we’ll talk tomorrow. [00:21:00]