Experts comment on AstraZeneca vaccine recommendation changes

Pharma News: The Australian Technical Advisory Group on Immunisation has recommended to the Federal Government that the AstraZeneca vaccine now only be given to those aged 60 and above. The Federal government has accepted ATAGI’s advice making the Pfizer vaccine the preferred vaccine for anyone under 60.

Dr Daryl Cheng, Medical Lead, Melbourne Vaccine Education Centre and Murdoch Children’s Research Institute, said “The recent modification to the Australian COVID-19 AstraZeneca vaccine rollout to the 60-69 year age group reinforces key foundational pieces in any mass immunisation campaign.

“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. The main safety challenge with a large population wide rollout is detecting and responding to safety signals which may not be evident in a clinical trial. The TGA and state-based surveillance systems, such as SAEFVIC in Victoria, are actively identifying and providing information for groups like ATAGI to come to clinical safety decisions.

“Australians want to know that our rollout is underpinned by a robust safety vaccine system, and any previous and future changes to the rollout system should be viewed in this context.

“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. 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 scientifically based, any change is likely to be frustrating for some and cause hesitancy around COVID-19 vaccination in others. The importance of building vaccine confidence in the population at this juncture is more crucial than ever. There is an abundance of resources available for the community, both about vaccination in general and also specifically about TTS, to ensure everyone can understand and evaluate the latest rollout change for themselves together with their health practitioner. It will require a creative nuanced effort between experts, government and the general public to boost collective confidence.”

Professor Adrian Esterman, Chair of Biostatistics at the University of South Australia, stated “The recent advice from The Australian Technical Advisory Group on Immunisation (ATAGI) that the AstraZeneca vaccine (now called Vaxzevria) should only be used for those 60 years or over is in line with recent advice from the European Medicines Agency (EMA) that nearly all cases of the rare clotting disorder have been in women under 60 years of age. However, this will again disrupt the vaccine rollout, since Pfizer vaccine supplies are limited, and we are unlikely to get additional Pfizer vaccine, or for that matter, Moderna or Novavax until much later this year. Unfortunately, the Federal Government put most of their eggs in the AstraZeneca basket, and this is now becoming a major problem. 

“The EMA also point out that the rare clotting disorders mostly occur after the first dose, so the risk for those under 60 who have already had their first dose and now getting their second dose is likely to be very small. There are clinical trials underway of the use of Pfizer as a second dose after AstraZeneca, and early results look good. So, this potentially will be another option once the full data are available.”

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, noted “The principle behind an age cut off relates to the assessment of risks versus benefits of the AstraZeneca vaccine. 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.

“Our regulatory bodies comprised of many genuine experts in this area constantly monitor the risks of vaccines in the form of adverse events, both in Australia and abroad, 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.

“We know for example that with a higher risk of COVID-19, some countries introduced a younger cut-off even as low as 30 years of age. Out of an abundance of caution and considering all of these and other factors, it would seem a sensible decision to increase the age cut-off for the use of this vaccine in our country at present. It is important to appreciate however that this may be subject to further changes in the future, in either direction, as the situation around us continue to evolve.

“In terms of the safety of this vaccine, our ability to recognise and manage this rare clotting syndrome has increased dramatically since it was first recognised so consequently the outcomes have improved. We must 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.”

Following the Government’s announcement, AstraZeneca said in a statement “We respect the decision taken by the Australian Government based on advice from the Australian Technical Advisory Group on Immunisation (ATAGI). This updated recommendation from ATAGI has been made in the context of low community transmission rates in Australia.

“AstraZeneca remains committed to supporting the rollout of the vaccination strategy in Australia and is confident that our vaccine has an important role in protecting Australians from the virus.”