Humans are terrible judges of risk. It’s why the gambling industry rakes in billions every year, why people are terrified of flying but not driving, and why another death possibly linked to the AstraZeneca vaccine may fuel vaccine hesitancy.
The 52-year-old woman died after developing a serious blood clot in her brain. Developing vaccine-associated blood clots is extremely rare — fatal cases are even rarer. Australia has administered 5.4 million COVID-19 vaccine doses, 3.6 million of which were AstraZeneca. There have been 48 confirmed and probable cases linked to the AstraZeneca vaccine and two deaths.
What we see v what we hear
UNSW school of psychology deputy head Professor Ben Newell tells Crikey much of how people perceive risk comes down to experience.
He conducted a study where people picked which simulated microworld they would choose to live in based on how prone the worlds were to natural disasters. The research found if people experienced the risk — that their simulated home experienced an earthquake — they were still likely to choose to live there because the risk was one they had experienced.
“People tend to overweight described risks and treat them as occurring more often than statistically,” he said.
“But if it’s an experienced risk, where you don’t tell a person how likely something is but over trials they learn there’s a 10% chance, then people tend to act as if they underweight prevalence — and see the risk as more like 5%.”
We saw this following the 9/11 terrorist attacks in the United States, where people were more likely to drive places than catch a flight — take an experienced, higher risk over a less experienced risk of flying.
But given Australians are vaccinated against more than a dozen diseases by the time they’re 16, wouldn’t that experience outweigh any vaccine hesitancy?
“I think the general idea is that [other vaccines] don’t translate into this situation because [this vaccine] is a new one,” Newel said.
At the mercy of biases
People’s perceptions are easily manipulated, Victoria University economist and climate change risk researcher Roger Jones tells Crikey.
“If we were purely rational, you would have a proportional reaction to risk based on probability,” he said. “But the problem is that if you’re unaware of something, the minute you take notice of it, it immediately becomes present.
“So even if something has a 0.0001% of a risk, you’re going to take more notice.”
Jones says there are many ways biases can be introduced into thinking — from the anchoring effect (wherein showing a higher number to a person before introducing data can lead people to perceive the data as lower), to the priming effect (being told something immediately before being told about the risk), to how familiar a person is with a certain risk.
“The fear of the unknown is a big factor, and if you don’t get immediate feedback on your decision it can prey on you,” he said.
Jones suspects the fact that blood clots can take some days to emerge is heightening people’s perception of risk due to the fear of the unknown.
Should we compare risks?
Research fellow at the Murdoch Children’s Research Institute’s vaccine uptake group Dr Jessica Kaufman tells Crikey there was some concern the news could fuel hesitancy, although officials had done well to highlight the rarity of the risk.
“It puts it more front of mind again for people as a potential risk, but doesn’t change the numbers that we’ve been sharing consistently throughout,” she said.
As more people get vaccinated and more data emerges, the rate of death or blood clots in Australia is decreasing, she says.
Even though risks are rare, comparing them with other risks — such as that of developing a blood clot from taking the contraceptive pill, or the risk of dying in a car crash — isn’t useful, she says.
“You don’t want to compare a completely arbitrary risk to something — like the risk of dying from smoking when people go, ‘Well that’s a choice that I’ve made.. ”
Part of this is due to a poor grasp of statistics, which Kaufman says can be overcome by visual depictions — showing one dot in 100,000 to represent a risk.
Perception of choice and control is also important: Kaufman says everyone should be able to choose which vaccine they get and when.
Yes, people are bad at calculating risks, and find grasping very large numbers difficult. In general people don’t make public health decisions, they make decisions about the conduct of their everyday life. Public officials are professionally required to make probability calculations using large numbers, but this not part of the lives of the majority of people. People operate on the basis of what is the right thing to do, disgust for doing the wrong thing and a highly differentiated sense of trustworthiness, mostly guided by people they know, not public figures.
This (untrustworthy) government has consistently asked people to make judgments on the basis of individual utility, which, as you point out, entails unfamiliar calculations. But even then, if the governments keep the border closed, the chance of dying of covid is much less than the 1 in 2,000,000 chance of dying of Astrazeneca side-effects. So it is not actually the problem of people’s limited intellect. The government have put themselves in a “trap” – they promise not to open borders so long as everyone isn’t vaccinated, but ask citizens to make individual utilitarian decisions, not public health decisions, which means they don’t get vaccinated, which means they don’t open borders, which means ….
The only way out is to place the question of getting vaccinated in an ethical framework, like the Victorian Premier did with asking people to support the lockdown for the publis good and praising them every day for doing so. But we have a liberal-individual government leaving public health decisions to individualist choices of citizens.
True enough, if the governments keep the borders closed. If they also ran built for purpose quarantine facilities the odds of dying of Covid in Australia would be astronomically small.
But we would still have to endure lockdowns on occasions. So far Victoria has been the bunny, but most of what they have endured has been bad luck, more so of recent times. What are the odds that a person who gets Covid in SA ends up seeing lockdowns in Vic, while SA is all fine. Gladys also probably doesn’t realise that she has been riding her luck. This track and trace stuff has been excellent, but still lucky for NSW.
And there are those people who want to go overseas again, so eventually the borders are going to have to be opened.
Once everyone who is willing or wants to be vaccinated has been vaccinated, then make it open season and let those who have not been vaccinated take their chances – same as we already do with the flu.
And to prevent the hospitals being overrun with sick unvaccinated people, turn the quarantine stations into infectious disease hospitals, like the one at Fairfield in Melbourne that was closed a couple of years ago.
“Perception of control is important.” Yes, and absent.
We did not get free choice of vaccine, but politicians did.
We get a C19 visa and no guarantee of benefit from its use.
We get AstraZeneca and no information about its effectiveness against current virus mutations, no information on boosters.
Most of us judge risk really well, and are undermined by frequent government secrecy and backflips.
5.4m shots despite bungled supply chains and confused federal responsibility? Don’t tell me citizens are responsible for saying “It is not a race”!
Well actually most people are very bad at judging risk, which is an established fact in psychological studies (although there is also the established fact that 70% of psychological studies could not be reproduced, so there’s that).
My experience is that people are terrible at analysing risk. As a former analyst I saw on a daily basis how bad people are at taking in information, sorting it, prioritising it and if there are any calculations involved then just fuggedaboutit.
Agree, but I will be less polite. Most adult Australians could not analyse their way out of a paper bag but are encouraged to ride in their hunches, feelings and opinions that in turn allows junk and pseudo science to enter and inform social narratives….. aka climate science, immigration, real estate etc.
I can recommend Kahneman’s ‘Thinking Fast and Slow’ for the layperson. Some of the Comment antivaxxers would do well to look at it.
People are bad at risk assessment.
The estimated VITT risk for over 50s has increased over time from 1 in 250,000 to 1 in around 100,000. Meanwhile the per-case risk of dying from VITT has dropped from 1 in 4 to 1 in 10.
That means the overall risk of dying of VITT has barely changed from 1 in 1,000,000.
That is consistent with 1 more Australian death after 1.5 million more AstraZeneca doses.
The problem is that most states haven’t had a COVID death so far this year and 1 in a million deaths from the vaccine is higher than the local toll from COVID, especially for people in their 50’s and 60’s.
So keeping COVID out effectively would be healthier than vaccinating with AstraZeneca.
Currently we cannot keep COVID out of Australia, so I got vaccinated, but I can see the worry, especially in QLD, WA, & SA.
So, in 2016 there were about 7,5 million people over 50. With your stat, that means 75 dots representing 75 people that will experience a form of blood clotting with low blood platelets. Of them some will be disabled for life and some will die.
In Europe one country has stopped the AZ jab. Other countries give people a choice to which vaccine they will get.
Australia forces people over 50 to get vaccinated with AZ. Indemnity is given, but people might die because of it.
Do you think Amber, this is morally acceptable? Especially when Australia is relatively safe from the sars-cov-2 virus?
Science is not an absolute, it is development of knowledge to current point in time. Vaccines will get better. To make them safe takes longer than a year.
Agree 100%!
If there is a one in million chance of something happening to an individual, we think that’s so tiny, it’s not even a real risk.
If there is a one in a million chance of something happening to a group of 8 million, from the perspective of the group, it is expected that 8 people will draw the short straw. No one can say which 8, they are all individually thinking “it won’t be me, i’d have to be dreadfully unlucky to come up the loser in a one in a million gamble. And they’d be right, they would be dreadfully unlucky, but according to the odds….that is precisely what is going to happen.
It can’t be denied, to deny it is to deny the very odds that science has calculated based on all of their data.
Having the jab “for the sake of the group” secretly means banking on someone else drawing the short straw, which is actually thinking only of yourself.
Refusing to play a part in the whole directive, that is going to guarantee 8 deaths, is regarded as thinking only of yourself, when in fact you are actually thinking of the welfare of the group.
And who is the group anyway? There seems to be two groups, in reality.
The group taking the risk, and the group pressing the other group to take the risk, “for the sake of the group”. (there’s a group overlap, I know)
So the actual real life situation, as i see it, is this:
We have a truckload of AZ vax, and we won’t be getting the mRNA any time soon. Soooo….
The government accept the fact that 8 people in the over 50s group are going to die, in order to get this vaccine rollout happening.
Sorry, but that’s the way it’s worked out. (Except there’s no sorry)
I’ve had the AZ jab, i had quite a bad reaction to it. I had it because i’m going to be travelling to stay with my 80 year old mum, and the thought of giving her Covid while looking after her doesn’t bear thinking about.
But am I happy that this is the way the situation has worked out? No. It’s really a poor development, and the government and apologists for the government who want to focus on “taking one for the group” and “one in a million chances” are overlooking what might have been, if the government had been more competent and had more foresight.
“One in a million” will be little solace to the loved ones of the two deceased, and i can betcha their supreme sacrifice won’t even be a distant memory, in the minds of the same people exhorting us to “think of the group”.
I tend to agree.
There might be another way to reduce risk without resorting to gratuitous references to other people’s math skills.
Most of the devastating cases have been in their early fifties. So raise the limit for Pfizer eligibility to 55.
No insults required just a simple acknowledgment that the science on this matter is imprecise as it is based on an historically small sample.
That historically small sample is now in the 10s of millions, so not really small at all. Also like Covid, medical staff know more about what to look for and how to treat it, so the odds of having clotting problems that aren’t treated I time will reduce over time.
I’m Im over 55, getting an AZ jab next Wednesday, no qualms about it. As for the other mRNA vaccines, I’m actually a little more sceptical about them. They are actually new technology, the AZ is basically the same system of all prior vaccines. I don’t think anything untoward will come of it, but if you all turn into zombies don’t say I didn’t let you know (just joking, of course)
“Australia is relatively safe from the sars-cov-2 virus” until we start to open up, which many powerful interests are demanding, or we get a leak of a faster spreading variant of the virus. Leaks from hotel quarantine occur frequently and the federal government has a notable record of quarantine failure. The big lockdown that occurred in Victoria could have happened in any state and once the virus spreads many infected people are likely to die or be disabled for a long time. We know it’s likely to happen because it’s already happened in one Australian state and also in other well controlled places like Singapore, Taiwan, Thailand and South Korea.
“Part of this is due to a poor grasp of statistics, which Kaufman says can be overcome by visual depictions — showing one dot in 100,000 to represent a risk.”
That poor grasp of statistics is exacerbated by the repeated failure of experts and journalists to convey comparable statistics. Just as the proportion of people developing blood clots after receiving the AZ vaccine is diminishing as the cohort who has received it increases, so to does the risk of dying of COVID-19, as ever greater numbers of people are infected AND recover. For the record, my chance of dying of COVID-19 is not simply the death rate per however many cases. Because I have to catch it in the first place before there is any risk that I could die of it. This is the number that needs to be compared to the rate of adverse events arising from vaccination. While these statistics are not quite such a ringing endorsement for widespread vaccination, they do have the benefit of being accurate. I suspect that the failure to be clear about this leads to the uneasy perception among many that they are not quite being told the whole truth. That uneasy perception is the lighter fluid that is fuelling increasing vaccine hesitancy. Tell the whole truth and accept the consequences. For the record, I have zero objection to this or any other vaccine (in principle). I have been pointing out this misleading use of statistics in relation to vaccination benefits for more than two decades. It is a repeat of the poor quality information provided about routine childhood vaccinations.
“That poor grasp of statistics is exacerbated by the repeated failure of experts and journalists to convey comparable statistics.”
Not surprising when people say things like…
“Electric vehicles generate three times less emissions than those with internal combustion engines.” One times less would be zero emissions so I suppose EVs must absorb twice what petrol-powered cars emit!
…and…
“Inflation fell by point one of one percent.” Hey, geniuses, what’s 0.1 of 1?
0.001%?
It ain’t just a lack of arithmetical ability, the literacy is pretty R/S as well.
Otherwise they might write “…a third of the emissions…”.
Even though that would be untrue.
But that would be to require factual accuracy, another black hole for the bien pissants.