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A doctor explains the risks of the AstraZeneca vaccine

Apr 13, 2021 • 16m 10s

Australia no longer has an official vaccination target, and one reason for the delay is our reliance on the AstraZeneca vaccine, which has been associated with health risks. Today, Dr Melanie Cheng, on weighing up the risks of the AstraZeneca vaccine, and what it all means for Australia’s rollout.

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A doctor explains the risks of the AstraZeneca vaccine

435 • Apr 13, 2021

A doctor explains the risks of the AstraZeneca vaccine

[Theme Music Starts]

OSMAN:

From Schwartz Media, I’m Osman Faruqi, this is 7am.

Australia no longer has an official vaccination target. After initially promising that all Australian adults would be able to receive the first dose of their vaccine by October, the federal government has now said it won’t be announcing a timeline.

One reason for the delay is our reliance on the AstraZeneca vaccine. Health risks associated with the vaccine have led to its use being restricted or paused entirely. Today, health columnist for The Saturday Paper Dr Melanie Cheng, on weighing up the risks of the AstraZeneca vaccine, and what it means for Australia’s rollout.

[Theme Music Ends]

OSMAN:

Melanie, last week, the Prime Minister held a pretty sudden press conference in the evening to talk about changes to Australia's vaccine rollout. Can you tell me what led to that announcement and what he actually said?

MELANIE:

Sure. Well, I'd go back to the Good Friday, the 2nd of April...

Archival Tape -- Michael Kidd:

“Good afternoon. My name is Professor Michael Kidd. I'm acting chief medical officer for the Australian Government Department of Health.”

MELANIE:

Michael Kidd confirmed the first probable case of thrombosis with thrombocytopenia in a 44 year-old man from Melbourne about 10 days after receiving his first dose of the AstraZeneca vaccine.

Archival Tape -- Michael Kidd:

“One probable case of this clotting disorder has now been reported in Australia overnight. And we are taking this very seriously.”

MELANIE:

And at that press conference, Michael Kidd mentioned that the Australian Technical Advisory Group on Immunisation, ATAGI, would be meeting again after the Easter break on Wednesday, the 7th of April, to discuss that particular case and also to discuss international developments regarding the AstraZeneca vaccine.

Archival Tape -- Michael Kidd:

“They've been monitoring the reports from overseas of these possible clotting disorders occurring 4 to 20 days after vaccination.”

MELANIE:

So on that Wednesday, I was kind of listening out to see if there would be some recommendations, but nothing came. It was only until late Thursday night that actually my parents text messaged me to say that there had been a sudden press conference.

Archival Tape -- Scott Morrison:

“...joined by the health minister. Of course, I'm joined by the chief medical officer of the Department of Health.”

MELANIE:

So I turned on my TV and I saw the Prime Minister speaking to announce that ATAGI had, in fact, released a statement.

Archival Tape -- Scott Morrison:

“ATAGI has reviewed that matter drawing on the international advice and data and provided recommendations to government, which the health minister and I have this evening accepted, that recommends that an advisory be provided for administration of the AstraZeneca vaccine for persons under the age of 50.”

MELANIE:

Which now recommended that the Pfizer vaccine would be the preferred vaccine over AstraZeneca for adults under the age of 50. At that same press conference, the chief medical officer expanded on the recommendation, saying that immunisation providers like myself should not give the first dose of AstraZeneca vaccine unless the benefit clearly outweighs the risk.

So in the wake of that press conference, I was worried about the possible increase in vaccine hesitancy, confusion amongst my patients, and also, of course, as was foreshadowed at that press conference, the delays to the rollout of the vaccine.

OSMAN:

Ok. So tell me about how we became aware of these problems with the AstraZeneca vaccine. Because we did get some hints this might happen as early as a month ago, right?

MELANIE:

So on the 11th of March this year, the European Medicines Agency released a statement.

Archival Tape -- Unidentified Reporter:

“Once again, the AstraZeneca vaccine is under the spotlight.”

MELANIE:

That was basically acknowledging that the Danish health authority had paused its vaccination campaign of AstraZeneca because of concerns about these unusual blood clots.

Archival Tape -- Unidentified Speaker:

“The European Medicines Agency has confirmed that the benefits of the AstraZeneca vaccine in preventing covid-19 overall outweigh the risks of side effects.”

MELANIE:

At the time, however, the EMA did say that the benefits of the vaccine still largely outweigh the risks. Then, on the 15th of March, Italy, France, Germany and Spain all suspended their rollouts of AstraZeneca in spite of really quite large numbers of Coronavirus in those countries, again citing concerns about this unusual blood clotting syndrome. Again, at that time, the EMA maintained that the benefits of AstraZeneca far outweighed the risks.

Archival Tape -- Unidentified Speaker:

“Vaccination is extremely important in helping us in the fight against covid-19, and we need to use the vaccines we have to protect us from the devastating effects.”

MELANIE:

And then, as I mentioned, you know, on the 2nd of April, Australia had its first case in this 44 year old man at Box Hill Hospital. And things kind of quite rapidly progressed from there. On Wednesday, the 7th of April, the EMA finally announced that this rare blood clotting syndrome would be listed formally as a very rare side effect of the AstraZeneca vaccine.

OSMAN:

Ok, so Australia is following a similar strategy to other countries, but can you tell more about what exactly what the health risks are here and how they manifests?

MELANIE:

So firstly, I like to point out that AstraZeneca is a very good vaccine in preventing illness and death in patients who contract Covid-19. So, you know, in the clinical trials, it was 100 percent effective in preventing death. But like any medicines, it does have side effects. Now, fortunately, the side effect of this thrombosis with thrombocytopenia is extremely rare across the world. The actual rates do differ depending on which country is reporting it. But we think that the final risk sits somewhere around four to six per million doses of the vaccine. So in terms of what the actual side effect is, we believe that it's immune mediated. So we think that it's the body's own immune system that is reacting in this abnormal way to the vaccine. And it's causing an activation of platelets. And platelets are a component of the blood which are responsible for clotting. So it's making these platelets extra sticky and causing them to form clots, particularly in unusual locations like the brain and also occasionally the abdomen, as in the case of the 44 year old man here in Melbourne.

And to complicate matters further, as these platelets get consumed in making these clots, they actually cause a reduction in the platelet numbers in the bloodstream. And that causes, paradoxically, an increased risk of bleeding as well. So we've got an increased risk of clotting and an increased risk of bleeding, which also makes treatment of this condition quite challenging. And as a result of that, sadly, the risk of dying, should you get this extremely rare side effect, is actually quite high. So it's about one in four people who get this side effect actually have passed away from it.

OSMAN:

We'll be back after this.

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OSMAN:

Melanie, I’ve found it hard to really get a read on how significant the AstraZeneca blood clotting issue is. On one hand, you see numbers that suggest that you’re more likely to be struck by lightning or be eaten by a shark than develop a life threatening blood clot, but on the other hand people under 50 are being told by the government to access a different vaccine. So how useful are those comparisons?

MELANIE:

So I think that human beings (and I include myself in this) are inherently bad at kind of conceptualising risk. We are very emotional. We're very much influenced by our past experiences. We're very much influenced by the experiences of our friends and neighbours and family. And so we find it difficult to process a lot of this information. And I myself have seen on social media a lot of very confusing comparisons. But I think, you know, I mean, think about this a lot. But the only comparison that is really relevant in this particular situation is comparing your risk of getting seriously ill and dying from Coronavirus should you contract it with your risk of getting seriously ill and dying from the vaccine.

If we give this vaccine to you, are you more likely to get a benefit from this vaccine or you're more likely to get a risk from the vaccine? So that's the only comparison, really, that we should be talking about. So I use myself as an example. So I'm in my 40s, I'm female. So using some of the international data, my risk of dying from Coronavirus should I contract it is one in one thousand five hundred approximately because I'm relatively young.

Now, my risk should I get the AstraZeneca vaccine of getting thrombosis with thrombocytopenia is much lower than that. It's one in two hundred and fifty thousand. And so someone might say to me, well, it makes sense. You should take the vaccine because, you know, that's a much lower risk. But what we need to take into account as well is that that one in one thousand five hundred risk is my risk of dying should I contract Covid-19. Now my risk of contracting Covid-19 in Australia right now when we have zero community transmission is arguably extremely low. Now, that can change. If there was to be an outbreak, that would could change, you know, within weeks. But right now, at this particular moment in time. When we take into account my risk of contracting it, then my risk of dying should I contract it and compare that to my risk of getting a severe rare side effect from the vaccine, they start to kind of become into a similar risk. And perhaps the risk of the vaccine right now outweighs a little bit the benefit for me in Australia at this time.

OSMAN:

So what you're saying is that the decision making around this isn't just a pure analysis of the risk of taking AstraZeneca in sort of isolation.

MELANIE:

Exactly.

OSMAN:

It's being applied to the specific Australian context and the rate of Covid transmission here.

MELANIE:

Exactly. And so so similarly to, you know, if I travel to PNG, a person in the age 85, OK, very elderly person, their risk of dying from Coronavirus should they contract it is one in four - extremely high. So that shifts the balance then. Even if they're in Australia and their risk of contracting the disease is still low, should they contract at the risk of dying is so high.

And the other thing we need to take into account here is that in the older population, we haven't seen these rare side effects of AstraZeneca. So the actual risk with a vaccine is lower for the elderly population. The risk of dying from Covid is higher.

So suddenly the scales have shifted and clearly the benefit is higher in that group. And so that explains the kind of current ATAGI recommendations. It's very complex. But I think if you look at it with examples, it kind of makes sense.

OSMAN:

Hm. And Melanie, I guess the other factor here is, is vaccine hesitancy. I feel like even if most of us decide to take the AstraZeneca vaccine at some stage, is there a concern that all of this media attention, all of this complexity around this might dissuade enough people that that then ends up having consequences for our goal here, which is to essentially vaccinate, you know, almost everyone to get to herd immunity?

MELANIE:

Yeah, and I think that's probably the most disappointing thing about all of this, is that it is likely to increase vaccine hesitancy. Research done at ANU shows that vaccine hesitancy is on the rise in Australia. And the factors driving a lot of that hesitancy are concerns about safety and efficacy of vaccines. And so these side effects really play into that narrative and they are unfortunately going to increase vaccine hesitancy.

What I would say is that the Australian Technical Advisory Group on Immunisations have made this advice, having reviewed the worldwide data on this. And so this is actually the system working to protect Australians from rare side effects of the vaccines. I think it's going to be an issue of health professionals like me and other community leaders trying to convey the information in a way that's really accessible because it is complex and it is confusing, being able to spend time with patients and simplify these kind of very difficult concepts and also to maintain transparency throughout the process.

OSMAN:

Melanie, thank you so much for talking to me today.

MELANIE:

No worries. My pleasure. Thank you.

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[Theme Music Starts]

OSMAN:

Also in the news...

According to Nine Newspapers, the Australian Federal Police have launched a new investigation into former special forces soldier Ben Roberts-Smith, who has been accused of war crimes. The investigation comes after Nine revealed Roberts-Smith had allegedly buried photographic evidence in his backyard, and had possession of at least five “burner” phones. Roberts-Smith has denied the allegations against him.

And former Prime Minister Malcolm Turnbull has said News Corp is Australia's 'most powerful political actor' and must be held accountable. Turnbull was giving evidence to a Senate inquiry into media diversity. In his testimony, Turnbull accused News Corp of running political campaigns against him.

I’m Osman Faruqi, this is 7am. See ya tomorrow.

[Theme Music Ends]

Australia no longer has an official vaccination target, and one reason for the delay is our reliance on the AstraZeneca vaccine, which has been associated with health risks. Today, Dr Melanie Cheng, on weighing up the risks of the AstraZeneca vaccine, and what it all means for Australia’s rollout.

Guest: Health columnist for The Saturday Paper Dr Melanie Cheng.

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7am is a daily show from The Monthly and The Saturday Paper. It’s produced by Ruby Schwartz, Elle Marsh, Atticus Bastow, Michelle Macklem, and Cinnamon Nippard.

Brian Campeau mixes the show. Our editor is Osman Faruqi. Erik Jensen is our editor-in-chief. Our theme music is by Ned Beckley and Josh Hogan of Envelope Audio.

New episodes of 7am are released every weekday morning. Subscribe in your favourite podcast app, to make sure you don’t miss out.


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435: A doctor explains the risks of the AstraZeneca vaccine