Following the updated advice from ATAGI related to the AstraZeneca Covid-19 vaccine and that it is now only recommended for those aged 60 and above, Australian experts have provided their perspectives on the issue.
‘Reinforces the risk-benefit ratio’
Dr Daryl Cheng, Medical Lead at the Melbourne Vaccine Education Centre and Murdoch Children’s Research Institute says this recently updated advice around the AstraZeneca vaccine “reinforces key foundational pieces in any mass immunisation campaign”.
“It also reinforces the importance of the risk-benefit ratio, which is a dynamic evolving concept based on both an individual’s and a population’s circumstances at that point in time,” says Dr Cheng.
“That has underpinned this most recent change, where the risks of vaccination with AstraZeneca in this age group, no matter how small, outweigh the potential benefits because of Australia’s current low rate of Covid-19 disease. Importantly, this risk-benefit balance may change again in the future – should circumstances change.
“While it may not have been the news we had hoped for, this change shows that our Australian vaccine safety surveillance system is both robust and constantly adapting to the latest available evidence,” says Dr Cheng.
‘Advice changes based on latest available information’
Professor Jill Carr, a virologist with the College of Medicine and Public Health at Flinders University underscores the fact that for those in their 50s who have had the first dose of the AstraZeneca vaccine “and three to four weeks have passed, then you are past the time frame for most thrombotic responses”, which she says, “are seen after the first dose but not second boost”.
Professor Carr adds that while this change in recommendations may cause “50-60-year-olds to feel uncomfortable and annoyed that they ‘feel’ they have been put at increased risk”, it’s important to remember that “in reality, this is real science, and recommendations change as more information becomes available”.
Decision based on new risk information
“ATAGI has made the right decision in acting on new risk information,” says Professor Julie Leek, Professor in the Susan Wakil School of Nursing and Midwifery at the University of Sydney.
“The aim is to keep people as safe as possible and minimise risk.
“It shows a strong commitment to vaccine safety and responsiveness. The system is working. It was clearly a difficult decision given the implications in a limited supply environment, but it was needed in view of the new information on the risk of the rare clotting syndrome – TTS – being slightly higher in the 50–59-year-old age group than first thought.”
‘Assessment of risks versus benefits’
“The principle behind an age cut off relates to the assessment of risks versus benefits of the AstraZeneca vaccine,” says Associate Professor Paul Griffin, Director of Infectious Diseases at Mater Health Services, Associate Professor of Medicine at the University of Queensland and Medical Director and Principal Investigator at Q-Pharm Nucleus Network.
“While the rare clotting syndrome known as TTS still has an overall low incidence, it does appear to be increased relatively in those that are younger.
“The opposite age correlation holds true for severe consequences of Covid-19, meaning that the older you are, the more likely you are to have a worse outcome from infection.
“Therefore, while it is likely the benefits of this vaccine in the form of protection from Covid-19 (particularly severe disease) still outweigh the risks overall, the difference between benefits and risks, is greater as you get older.”
He adds that Australian regulatory bodies “constantly monitor the risks of vaccines in the form of adverse events … as well as the benefits in terms of the risk of catching Covid-19”.
“In our country we are fortunate to have excellent control of the virus and therefore a very low background rate of severe disease.
“We also are fortunate enough to have an alternate vaccine in the form of Pfizer, albeit still in relatively short supply.
“Putting this all together it made sense to bring in an age cut-off, one that considered all of these variables and one that was always subject to change as the situation evolved,” he adds.
According to Associate Professor Griffin the ability of medical professionals to “recognise and manage this rare clotting syndrome” has improved “dramatically since it was first recognised”, which has, in turn, improved outcomes.
He says that it’s important to “keep in mind that this is a highly effective vaccine, and it remains safe in the population in which we are using it”.
“So, if you are eligible for this vaccine, this change in how it is being used should not dissuade you from doing so,” says Associate Professor Griffin.
AstraZeneca: ‘Patient safety the highest priority’
According to a statement released by AstraZeneca following the updated advice, the company says that it respects the decision by the Australian Government based on advice from the ATAGI, which they add has been made in the context of low community transmission rates in Australia.
The statement adds AstraZeneca remains committed to supporting the rollout of the vaccination strategy in Australia and is confident that their vaccine has an important role in protecting Australians from Covid-19.
“Our vaccine has helped to save tens of thousands of lives and extensive data from clinical trials and real-world evidence from millions of people shows that our vaccine is highly-effective against Covid-19,” says the company.
“Regulatory authorities around the world have stated that the benefit of using our vaccine significantly outweigh the risks across all adult age groups.
“Patient safety is AstraZeneca’s highest priority, and we continue to work closely with the TGA and other regulators around the world.
“Our global commitment remains to play an important role in addressing the current global health emergency posed by Covid-19 by providing our vaccine at no profit during the pandemic.”
