TGA approval clarifies AstraZeneca booster use

The Therapeutic Goods Administration (TGA) has given provisional approval for the use of AstraZeneca as a booster in a move that could spread understanding of its availability.
 
The AstraZeneca COVID-19 vaccine – officially known as Vaxzevria following a name change last year – was already permitted as a booster if specific conditions were met according to Australian Technical Advisory Group on Immunisation (ATAGI) advice released in December.
 
ATAGI states the use of AstraZeneca is possible for people who had previously had the vaccine for their first two doses with no contraindications, or for patients who had a ‘significant adverse reaction’ following a previous mRNA vaccine dose.
 
The TGA said the AstraZeneca booster can be received ‘if clinically indicated’ with reference to official guidance.
 
The two currently approved mRNA vaccines remain the preferred option for booster doses.

In its announcement, the TGA also said any decision to opt for AstraZeneca as a booster needs to be made in consultation with a medical professional.
 
University of Queensland Associate Professor Paul Griffin, an infectious diseases physician and microbiologist, said he believed the main result of the announcement will be to clarify the public’s perception of whether AstraZeneca is an option for a booster.
 
‘I don’t really think this announcement changes very much,’ Associate Professor Griffin told newsGP.
 
‘It maybe makes it a little more streamlined or official for those people that that do want to use that vaccine as a booster.
 
‘It’s essentially been available already for people, particularly [those] who had a contraindication to receiving the other vaccines.
 
‘But this just makes it a bit clearer that AstraZeneca is in fact an option, because I think for a lot of people even though it was there, that perhaps wasn’t clear.’
 
Last month, AstraZeneca shared preliminary analysis from a trial that indicated a third dose of the vaccine enhanced the immune response of those who received it, whether or not they had AstraZeneca as their primary course.
 
It showed that three doses of the vaccine produced neutralising antibody levels against Omicron that were similar to those produced against the Delta variant after two doses. 
 
The results were among people who had previously vaccinated with either AstraZeneca or an mRNA vaccine.
 
Analysis also showed antibody levels against Omicron after the booster shot were higher than among people who had been infected with COVID-19 and recovered naturally.
 
Professor Sir Andrew J Pollard, the chief investigator and director of the Oxford Vaccine Group at the University of Oxford, said the studies show a third dose of AstraZeneca ‘strongly boosts’ immunity against COVID-19.
 
‘The Oxford-AstraZeneca vaccine is suitable as an option to enhance immunity in the population for countries considering booster programs, adding to the protection already demonstrated with the first two doses,’ he said.
 
While a number of studies have considered heterologous vaccination with AstraZeneca as a booster, Associate Professor Griffin believes the evidence so far suggests the Pfizer and Moderna vaccines are more effective.
 
‘The advice would still be to have an mRNA booster, if possible,’ he said.
 
It is a view also held by Dr Andy Flies, a Senior Research Fellow at the University of Tasmania’s Menzies Institute for Medical Research.
 
He believes that AstraZeneca is best employed as a booster among those who had an adverse reaction to other vaccines.
 
‘The AstraZeneca booster will be most useful for people that had strong side effects to the mRNA vaccines or have histories of myocarditis and pericarditis,’ he said.
 
The announcement this week means three vaccines have now been provisionally approved for use as a booster.
 
Pfizer was approved as a booster dose in October last year, with approval subsequently provided to Moderna in December.
 
A further vaccine, Novavax, has been approved for use as a primary vaccination course with an application for use as a booster currently underway.
 
The TGA said an Australian Public Assessment Report for their decision to approve AstraZeneca as a booster will be published in the next few days.
 
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