EXPLAINER

How risky is the AstraZeneca vaccine?

The potential AstraZeneca danger has been overblown. Picture: Shutterstock
The potential AstraZeneca danger has been overblown. Picture: Shutterstock

A 61-year-old woman in Western Australia has died of blood clots after receiving the AstraZeneca vaccine. The health authorities have linked the death to the vaccine because there is no evidence of any other likely cause.

She is the third person in Australia to have died of what the authorities think is a side-effect of the AstraZeneca vaccine.

The latest official figures for potentially serious blood clots from the AZ vaccine are: 76 cases overall, of whom three have died.

About 5 million doses of the AstraZeneca vaccine have been given (of the 8.8 million jabs of all vaccines).

To give it its formal title, the condition is known as immune thrombocytopenic purpura.

The way ITP is linked to the AstraZeneca vaccine is still being studied but the research so far suggests there's a problem in one case for every 100,000 AZ doses administered.

Three people have died out of 5 million doses; adding up to one death per 1.5 million injections.

Advice on the AZ vaccine has changed as politicians and health experts weigh the risk and benefits.

Last month, the recommended age for AstraZeneca was raised to 60.

But Australia's Prime Minister Scott Morrison announced last week younger Australian adults who wanted the AstraZeneca vaccine could ask their GP for it.

There may now be confusion about safety.

So is it safe?

The overwhelming view of doctors is that the approved coronavirus vaccines, including AstraZeneca, are very safe.

As with all treatments, doctors assess other conditions before prescribing a medicine: is the patient pregnant or allergic to a substance or suffering from high blood pressure? They then prescribe or don't prescribe.

"Nearly all the world's immunologists, virologists, medical professionals and public health experts agree COVID-19 vaccines, including AstraZeneca, have minimal risk to recommended subgroups and significant benefit," Professor Nathan Grills of the Nossal Institute for Global Health at the University of Melbourne said.

And he has personal experience of the dangers of not getting vaccinated.

"I have also lost a friend due to AstraZeneca," he said.

"He was 70 years old and listened to scaremongers and decided against vaccination, only to die from COVID-19 in India.

"Ironically, he was taking aspirin to prevent another heart attack, a medication which poses a significantly higher risk than AstraZeneca."

Around one in 10 Australians take aspirin every day to prevent a stroke or a heart attack, he said, "but statistically, aspirin is 200 times more dangerous than AstraZeneca - resulting in around one death per 1000 people."

Are other medicines risk-free?

They are not.

The contraceptive pill can cause blood clots in five to 12 women in every 10,000 who take it.

Paracetamol is available over countless counters and no doubt stocked in millions of medicine cabinets. Because it is the painkiller to hand, it is overused.

One of the country's pharmacy magazines says. "Public misunderstanding about the safety of paracetamol is contributing to misuse and accidental overdose.

Easy access to large quantities of paracetamol may also be contributing to intentional overdose."

A study of its use from 2004 to 2017 concluded "in that time, we recorded more than 95,000 paracetamol-related hospitalisations".

"More than 200 people died from paracetamol poisoning in Australia in the 10-year period," said Dr Rose Cairns from the Sydney Pharmacy School, one of the authors of the report in the Medical Journal of Australia.

None of that means that we should stop using paracetamol. It only means if we focus on tiny risks we lose the immense benefits of a drug.

Risk versus benefit

The problem is "cognitive bias" - the way we choose bits of information selectively and ignore others.

We may focus on the dangers of something, magnifying them in our minds. When headlines scream about danger, we may overreact and not see greater risks.

"We tend to discount or accept the risks of daily activities such as smoking and focus attention on the risks of the vaccination," said Dr Ahona Guha, a psychologist in Melbourne.

"Some other things that are more likely to occur than getting a blood clot after the jab? Winning the lottery, giving birth to triplets, dying after being stung by a bee, dying in a car crash, or being struck by lightning.

"I certainly don't intend to quit my day job and wait to win the lottery. Why would I take a similar gamble on my health?"

Should you have the jab or go bungee jumping?

It's not a choice, of course, but diseases expert Hassan Vally of La Trobe University has assessed risk.

He told this paper far more people die running a marathon than have died from the AstraZeneca vaccine. The same goes for "adventure" sports like rock climbing and bungee jumping.

In everyday life, far more people are murdered every year in Australia than are dying from blood clots after vaccination.

He says the risk of dying from the blood complaint after the first dose of the AstraZeneca vaccine "is similar to the risk of being killed by lightning in a year in Australia. And this pales in comparison when compared to other risks, such as the risk of dying in a car accident".

So ...

Official advice remains: Pfizer is preferred for people under 60 but AstraZeneca can be used "where the benefits clearly outweigh the risk for that individual and the person has made an informed decision based on an understanding of the risks and benefits".

But no doctor thinks the risk is high. And it's better than no vaccine at all.

This story How risky is the AstraZeneca vaccine? first appeared on The Canberra Times.