Yesterday, the Australian Technical Advisory Group on Immunisation (ATAGI) revised its recommendations for the AstraZeneca COVID vaccine once again.
People under the age of 60 are now eligible for Pfizer, while AstraZeneca is only recommended for people 60 years or more old. The previous age cut-off for AstraZeneca was 50.
The decision came because of the latest 12 cases of the vaccine-induced rare blood-clotting condition called Thrombosis with Thrombocytopenia Syndrome (TTS). Seven of the cases were in people aged 50–59. Among those, a 52-year-old woman became the second Australian fatality of TTS.
According to the new statistics, the incidence rate in the 50–59-year-old age group went from under 2 cases every 100,000 vaccine doses to 2.7.
Still rare, but deemed to tip the risk-benefit balance.
It was the right decision, says Professor Mike Toole, an epidemiologist at the Burnet Institute.
“We still have very low numbers of cases in Australia,” Toole says. “You’ve got to balance the risks of side effects and the benefits of the vaccine. You can’t give a vaccine that is effective in preventing a disease we don’t have. The risk [of clotting] is now a lot more than we used to think.
“If we were like the UK, you’d have a very different risk-benefit assessment.”
But the new announcement has sparked confusion and doubts among Australians, with many in the over-60 age range now refusing to get their AstraZeneca shot.
That has several consequences.
The already fractured vaccination campaign will probably suffer another stall, which means that the risk of severe COVID outbreaks will linger for longer. Already limited Pfizer doses now have a couple of million more Australians competing for them. Younger Australians are still left to wait.
“[ATAGI experts] would have thought that through very carefully,” says Toole. “But I think they felt they had a responsibility to make the safest recommendation for the Australian people.”
The government hopes that the new ATAGI advice will encourage hesitant over 50s to get a Pfizer shot – supply and demand issues notwithstanding. But many over 60s feel they have been left with no other option than to either get AstraZeneca or not get a vaccine at all until other brands are available. Some think they have been relegated to the less desirable, less efficacious vaccine.
“I don’t think that was planned,” says Toole. “No-one could have anticipated this side effect.” But it is likely a consequence of decisions that saw Australia fail to secure enough vaccine deals early enough.
With about 60% of people over 60 already vaccinated in Australia, AstraZeneca has now been relegated to a minor role in the national rollout. Hundreds of thousands of AstraZeneca doses now sit on shelves, at risk of passing their expiry dates.
“We should provide [these shots] to our neighbours,” says Toole. “We are making 1 million doses of AstraZeneca a week here. Let’s start giving it away to countries where the risk of dying of COVID is much higher.
“We must make sure that they also assess the risk in their populations. But even if we gave it to all our neighbouring countries and said ‘you can only give it to people over 60’ that would be good.”
Dr Manuela Callari is a Sydney-based freelance science writer who specialises in health and medical stories.
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