For people aged over 60, the health advice from ATAGI is simple: get whatever vaccine you can. This is because your chances of dying from COVID-19 are quite high should you fall sick.
For people over 18 in Greater Sydney, the message is now equally simple: get vaccinated with any available vaccine, including AstraZeneca. This is because the chances of getting COVID-19 have increased dramatically for everyone living in that area.
For people under 60 who do not live in Greater Sydney, ATAGI’s advice is less clear: prefer Pfizer over AstraZeneca. In areas with no or few infections, ATAGI feels the risks of AstraZeneca outweigh the benefits.
However, people under 40 can access AstraZeneca if their GP agrees.
What are my chances of catching COVID-19?
Over enough time, your chances of catching COVID-19 rise to about 100 per cent. This might surprise you, but think about it: eventually, Australia will reopen and the virus will circulate. If you live a sufficiently long life, you will almost certainly catch COVID-19.
This is an argument in favour of vaccination in general. But the question here is whether you should get AstraZeneca now, or wait for Pfizer.
The government signalled earlier this month that people under 40 might become eligible for Pfizer in September or October, but vaccine rollout deadlines seem to have a way of being missed at the moment…
So it’s hard to say how long you might have to wait, but it will be months. Then add on the time to get an appointment, plus the four- to six-week wait for a second dose, plus another two weeks after that for your antibody levels to peak.
What is the risk of getting COVID-19 in that time frame?
In Sydney on July 11, ATAGI estimated it was about 10 per 100,000, with that number going up by two per day (it has already reached 100 per 100,000 in Fairfield). Given the significant increase in cases since then, we can expect that number to be much higher now.
What if Sydney’s outbreak were to reach the scale of Melbourne’s second wave? The infection rate rises to 275 per 100,000. That puts it in the same range as your chances of catching the flu.
Your individual situation may put you at more or less risk. For example, a taxi driver would probably be at much greater risk. If you are the sole occupant of a plastic bubble, you are at lower risk.
In other states without outbreaks, that number is obviously much lower.
But the problem with COVID-19 is we are forecasting future risk. No one sees an outbreak coming, and by the time you think, ‘I need to get vaccinated,’ it may be too late. You may struggle to get a vaccine when an outbreak starts. You may have to wait days or weeks – and then weeks more to get a second dose and full protection.
If I get COVID-19, what are my chances of being seriously harmed?
You can look up your chances of dying if you are infected with COVID-19 here. Scroll down to table 3 and look in the column marked COVID-19 IFR.
I’m 30, so my risk of death is somewhere in the range of 0.004 per cent.
That’s a global figure, but one of the authors, University of Wollongong epidemiologist Gideon Meyerowitz-Katz, tells me it’s probably in the right range for Australia.
This tells us an important truth about COVID-19: your risk does not slowly rise as you age, it goes up sharply and dramatically. If you are 85 years or older and catch COVID-19, you have a more than one in four chance of dying from it. That’s a lot! This explains why the government wants people over 60 to get any vaccine they can get their hands on.
Age increases your risk, as do other factors. Here’s an alphabetic list, which includes things like diabetes, smoking and obesity. Take pregnant women: a five-times higher risk of getting hospitalised, a three times higher risk of needing a ventilator.
What about long COVID? At this stage, it’s difficult to tell just how many people will get it, and for how long. Tracking of more than 20,000 people in the UK found 13.7 per cent still reported symptoms more than three months after the initial infection.
What’s my risk of dying from AstraZeneca’s vaccine?
That number drops to 1.6 for people aged 30 to 39. But that’s just using Australian data – and we haven’t vaccinated many young people.
“Analysing the risk of [clotting] in young people, aged between 20 and 39, should be done on the basis of the very large amount of information overseas. As an epidemiologist, my best estimation, taking into account all the data, is a risk of three per 100,000 in 20 to 39-year-olds,” the University of Sydney’s Professor Robert Booy told me.
The numbers for risk of death or serious injury from a clot are even more uncertain, as they are very small.
On current Australian data, if you get a clot, in about 95 per cent of cases, it is not fatal.
As a 30-year-old, that puts my risk of dying from an AstraZeneca clot at 0.00008 per cent, or, as Mr Meyerowitz-Katz helpfully puts it, “one in 1.25 million”. That’s less than the risk of being struck by lightning.
What about serious injury from AstraZeneca? About one-quarter of Australia’s clotting cases end up in hospital. That’s a risk of about 0.0004 per cent.
As we know, our brains are pretty hopeless at making sense of a number that small. Consider an MCG filled with 100,000 people, each aged between 30 to 39, each vaccinated with AstraZeneca.
On the odds we have, one or two people in the entire stadium would get a clot. How many MCGs filled with vaccinated people would we need, on average, to see a single death? Ten.
Will AstraZeneca protect me from COVID-19?
Yes. Focusing just on Delta, the current variant of the virus running through Sydney, the best real-world data we have suggests two doses of AstraZeneca is 67 per cent effective against stopping a Delta infection. More important, those two doses are 92 per cent effective against serious illness or death.
How much does getting vaccinated help the broader community?
While a vaccine comes with risks to the individual, the benefits are much broader. By being vaccinated, you contribute to stopping the spread of the virus.
Consider every person you interact with each week: workmates, friends, family, your partner and children. If you catch the virus, each of these people is now directly at risk of catching it from you. Do any of them have risk factors that would make them more likely to get seriously ill or die?
And every vaccine is a step toward Australia being able to more fully reopen.
Putting it all together – and why I chose to get a jab
I chose to get a jab because I think, in my individual case, the benefits outweigh the risks.
I think I am at low risk of catching the virus before I can access a Pfizer jab. I think I am at low risk of getting long COVID, and at very low risk of dying.
But my partner, Caroline, is pregnant. Should she catch COVID-19, the risks she faces (and the risks to our unborn child) are concerning. At the time I got my jab, she was not eligible for a vaccine. Given we live together, I think there is a very high chance if I got sick I would pass the virus on to her.
Given my risk of death from AstraZeneca is so, so low (in the order of 0.00008 per cent), I felt the benefits substantially outweighed the risks.
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