AstraZeneca: Side effects & blood clots
Since early 2020, Covid-19 has been a global pandemic. It’s certainly not the first global pandemic — if you thought it was, perhaps try googling the Justinian Plague, the Black Death (which we can thank for the invention of quarantine), or the Spanish Flu of 1918 (which, despite its mundane sounding title, killed 500 million people). But it’s taken ideas that previously have been science fiction — like national lockdowns, labs desperately researching a cure, and mass vaccinations — and made them our reality.
The race by global scientists to find a solution to the virus has now resulted in Australia having two vaccines available, which are now being progressively rolled out across the Australian population. One of them — probably the most controversial — is the Oxford–AstraZeneca COVID-19 vaccine, generally just called “AstraZeneca” or “AZ”.
Does it work?
The obvious first question when it comes to the AstraZeneca vaccine is “does it work”? Does it allow your body to resist the Covid-19 virus? And the good news is that the answer is “Yes”.
Although it doesn’t make you immune to Covid 19 (no vaccine does that), the AstraZeneca vaccine does make you highly resistant to it. Studies in Scotland have shown that the vaccine is more than 80% effective against the Alpha variant of the Covid-19 virus. Even in the case of the highly aggressive and contagious Delta variant, AstraZeneca has still proved to be more than 60% effective at resisting the virus.
Now, if you were hoping for a 100% effective, fast-acting cure like you might see in a movie, then 80% — or even 60% — sounds like a somewhat disappointing number. That’s still 40% ineffective, isn’t it?
Perhaps it’s better to think of it a little like a soldier’s body armour. Soldiers going into war zones are aware that their body armour and helmet doesn’t make them invincible. Their helmet and armoured vest mostly protect the more critical parts of the body (the head and chest), but there are still many places where a bullet or piece of shrapnel could take them out of action. So why do they still wear the armour? Because an 80% chance — or even a 60% chance — of not dying is pretty good!
The Covid vaccines we currently have were never expected to make everyone 100% immune. But even in the very serious scenario of a Delta variant Covid-19 outbreak, good vaccine coverage with AstraZeneca would mean three in every five people directly exposed to the virus won’t be affected. And that’s excellent news.
What side effects can it cause?
Sure, there are potentially a few side effects.
In some people (less than 1-in-10), the vaccine has been known to cause unpleasant symptoms — vomiting, diarrhoea, fever, swelling, and redness at the injection site. These symptoms might take you out of action for a day or two but generally clear up within a few days.
Even less frequently, a little under 1 in every 100 people suffer from enlarged lymph nodes (like from a cold), decreased appetite, dizziness, sleepiness, sweating, abdominal pain, itching and rashes. Again, these can be uncomfortable, but they generally clear up within a day or two.
What about blood clots?
Alright, let’s talk about the elephant in the room. Yes, there is a very small chance of AstraZeneca causing blood clots and some chance that this could be fatal. The odds are roughly 4 in a million of clotting resulting from the vaccine, and around a 1-in-4 chance that such a clot could be fatal. That means your odds of dying from a blood clot due to the AstraZeneca vaccine are almost exactly one-in-a-million.
Let’s break that down a little and put it in context. Here’s a few things that carry significantly more risk of killing you than AstraZeneca related blood clots.
- Aspirin — Taking aspirin on a day-to-day basis has around a 100-in-a-million chance of killing you
- Childbirth — Currently, the odds of childbirth being fatal are around 67-in-a-million
- The Pill — Using an oral contraceptive carries around a 30-in-a-million risk of fatal blood clots.
- General Anesthetic — Every time you have a general anesthetic for an operation, you’re taking an 18-in-a-million risk of not waking up.
- Struck by Lightning — Your odds of dying from a lightning strike in Australia are around 2-in-a-million
(Source: Australian Academy of Science & ABC News)
Yes, you’re twice as likely to be killed by lightning as by an AstraZeneca related blood clot. And using the pill for birth control is thirty times more dangerous.
If the entire Australian population were given the AstraZeneca vaccine, we would expect around 25 deaths nationwide from related blood clotting. That’s enough names to fill a single A4 lined sheet of paper.
To compare, the current count of Covid deaths in Australia is currently over 1300. At least 90 of those happened in the week this article was written. And that’s not a big number in global terms — we’re one of the countries doing relatively well with Covid-19! In the US, the casualty list is over 700,000 — meaning Covid is starting to nip at the heels of cancer and heart disease as a leading cause of death in the US.
For reference, blood clot deaths are enormously common. It’s estimated that around 10% of the deaths in Australia are caused by blood clots causing things like strokes, heart attacks, and venous thromboembolism* (VTE). So really, just being alive is 100,000 times more likely to give you a fatal blood clot than AstraZeneca.
(* Source: Thrombosis Australia)
Then why am I hearing about AstraZeneca blood clots all the time?
Quite simply, blood clots make good news. “Vaccine is safe other than a few flu symptoms” doesn’t make headlines and doesn’t generate clicks on social media.
“Vaccine causes fatal blood clots” is something that people click on. I mean, let’s be honest. That’s how you got to this article, isn’t it? Clicking a headline that caught your eye, or Google searching those terms?
And the problem with that is that our brains have this thing called the availability heuristic, — which means that the more we hear about and think about something, the more plausible and likely it seems. If we hear a bunch of different references to AstraZeneca blood clots in the news, then it feels like the odds of it happening are about 1 in 10.
If you’re finding that hard to swallow, consider this. It’s known that there’s around an 8-in-a-million chance of AstraZeneca causing an Anaphylactic reaction. Now, anaphylaxis is life-threatening but can be easily treated on the spot by a nurse with an EpiPen — that’s one of the reasons why you have to wait around for a while after your injection. There’s also rare cases of the vaccine causing capillary leak syndrome, or Guillain-Barré syndrome. So why don’t you know about those risks? Because they don’t make good news. They don’t sound scary, and Guillain-Barré syndrome looks kind of hard to pronounce.
The truth is that headlines aside, AstraZeneca does the job. Rolled out across Australia, it’ll likely save hundreds if not thousands of lives. And it’s way safer than many of the medications you probably take on a daily basis.
How can I be ready for someone around me suffering a clot?
As mentioned, blood clots cause large numbers of deaths every year — generally in the form of strokes (resulting from a blood clot in the brain) or heart attacks (from a clot in the heart). Although these two can be life-threatening, prompt medical intervention can potentially prevent such an incident from being fatal.
If you want to know how to recognise the signs of a stroke or heart attack, your best option is first aid training. FirstAidPro is a registered training organisation (RTO #40407) that offers professional standard first aid courses to both professionals and the general public. Our most popular training course, HLTAID011 Provide First Aid, can train you in recognising and responding to a wide variety of medical issues, including cardiac problems and strokes. Why not be ready for that moment, so you’re not left helpless when someone is sick or injured on the floor.
