• November 27, 2021

Doing the math on the AstraZeneca COVID vaccine

For the people over 60 years old, the ATAGI health tip is simple: get any vaccinations you can. This is because your chances of dying from COVID-19 are quite high in case you get sick.

For the people 18+ in Greater Sydney, the message is now equally simple: get vaccinated with any available vaccine, including AstraZeneca. This is because the chances of contracting COVID-19 have increased dramatically for everyone living in that area.

To people under the age of 60 who do not live in Greater Sydney, ATAGI’s advice is less clear: I prefer Pfizer over AstraZeneca. In areas with little or no infection, ATAGI believes that the risks of AstraZeneca outweigh the benefits.

However, people under the age of 40 can access AstraZeneca if their GP agrees.

What are my chances of getting COVID-19?

With enough time, your chances of contracting COVID-19 increase to about 100 percent. This might surprise you, but think about it: Eventually Australia will reopen and the virus will circulate. If you live a long enough life, you will almost certainly contract COVID-19.

This is an argument in favor of vaccination in general. But the question here is whether you should get AstraZeneca now, or wait for Pfizer.

The government noted earlier this month that people under the age of 40 might be eligible for Pfizer in September or October, but the vaccine launch deadlines seem to have a way of not being met at this time …

Therefore, it is difficult to say how long you will have to wait, but it will be months. Then add in the time to get an appointment, plus the four to six week wait for a second dose, plus other two weeks after that for your antibody levels to peak.

What is the risk of contracting COVID-19 in that period of time?

In Sydney on July 11, ATAGI estimated it to be approximately 10 per 100,000, with that number increasing by two a 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 the Sydney outbreak reached the scale of Melbourne’s second wave? The infection rate rises to 275 per 100,000. That puts you in the same range as your chances of get the flu.

Your individual situation may put you at greater or lesser risk. For example, a taxi driver would probably be at a much higher risk. If you are the sole occupant of a plastic bubble, you are at less risk.

In other states without outbreaks, that number is obviously much lower.

But the problem with COVID-19 is that we are forecasting future risks. No one sees an outbreak coming, and by the time you think, ‘I need to get vaccinated,’ it may be too late. You may have a hard time getting a vaccine when an outbreak starts. You may need to wait days or weeks, and then weeks for a second dose and full protection.

Queues at a vaccination center in Homebush, Sydney, in early July.Credit:Getty

If I get COVID-19, what are my chances of serious harm?

You can check 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 years old, so my risk of death is in the 0.004 percent range.

That’s a global figure, but one of the authors, University of Wollongong epidemiologist Gideon Meyerowitz-Katz, tells me that it’s probably in the correct range for Australia.

This tells us an important truth about COVID-19: Your risk does not increase slowly as you age, it increases dramatically and dramatically. If you are 85 or older and contract 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 whatever vaccines they can get.

Age increases your risk, as do other factors. Here is an alphabetical list., which includes things like diabetes, smoking, and obesity. Take pregnant women: a five times greater risk of being hospitalized, a three times greater risk of needing a ventilator.

What about the long COVID? At this stage, it is difficult to know how many people will get it and for how long. Tracking over 20,000 people in the UK found that 13.7 percent still reported symptoms more than three months after the initial infection.

What is my risk of dying from the AstraZeneca vaccine?

If you gave 100,000 people between the ages of 18 and 29 a dose of AstraZeneca, you would expect to record 1.9 blood clots, according to Australian data.

That number drops to 1.6 for people ages 30 to 39. But that’s just using Australian data, and we haven’t vaccinated many young people.

Loading

“Analyzing the risk of [clotting] in young people, between 20 and 39 years old, it must be done on the basis of the large amount of information abroad. As an epidemiologist, my best estimate, taking all the data into account, is a risk of three per 100,000 in people aged 20 to 39, ”Robert Booy, a professor at the University of Sydney, told me.

The figures for the risk of death or serious injury from a clot are even more uncertain as they are so small.

Based on current Australian data, if you have a clot, in about 95 percent of cases, it is not fatal.

As a 30-year-old, that puts my risk of dying from an AstraZeneca clot at 0.00008 percent, or, as Mr. Meyerowitz-Katz kindly puts it, “one in 1.25 million.” That’s less than the risk of being struck by lightning.

What about serious injuries from AstraZeneca? About a quarter of Australia’s clotting cases end up in the hospital. That’s a risk of about 0.0004 percent.

As we know, our brains have no hope of making sense of such a small number. Consider a full CGM of 100,000 people, each between the ages of 30 and 39, each vaccinated with AstraZeneca.

Based on our odds, one or two people in the entire stadium would get a clot. How many CGMs full of vaccinated people would we need, on average, to see a single death? Ten.

Will AstraZeneca protect me from COVID-19?

Yes. Focusing only on Delta, the current variant of the virus that runs through Sydney, the best real world data we have suggests that two doses of AstraZeneca are 67 percent effective in stopping a Delta infection. More importantly, those two doses are 92 percent effective against serious illness or death.

How much does getting vaccinated help the community in general?

While a vaccine carries risks for the individual, the benefits are much broader. By being vaccinated, you help stop the spread of the virus.

Consider each person you interact with each week: coworkers, friends, family, your partner, and children. If they contract the virus, each of these people is now at direct risk of contracting it. of you. Do any of them have risk factors that would make them more likely to become seriously ill or die?

And each vaccine is a step for Australia to reopen more fully.

Putting it all together, and why did I pick a jab

I chose to receive a jab because I believe that, in my individual case, the benefits outweigh the risks.

Liam receives his first dose of AstraZeneca.

Liam receives his first dose of AstraZeneca.

I think I am at low risk of getting the virus before I can access a Pfizer jab. I think I have a low risk of long-term COVID and a very low risk of dying.

But my partner, Caroline, is pregnant. If you contract COVID-19, the risks you face (and the risks to our fetus) are concerning. At the time I received my vaccination, she was not eligible for a vaccination. Since we live together, I think there is a great chance that if I get sick I will pass the virus on to you.

Since my risk of death from AstraZeneca is so, so low (on the order of 0.00008 percent), I felt that the benefits substantially outweighed the risks.

If you appreciated this article, Consider signing up for Examine, a free newsletter, delivered to your inbox each week.

Leave a Reply

Your email address will not be published. Required fields are marked *