Confusion over PM’s call to shorten interval between AstraZeneca doses

The recommendation from the Prime Minister comes as New South Wales’ Delta outbreak continues to grow, with 44 new cases of COVID-19 confirmed on Friday and restrictions for Greater Sydney tightened.
 
‘We would … be encouraging the 8–12-week second dose to be done at the earlier part of that 8–12-week period,’ Prime Minister Morrison said.
 
‘Given the risks to people of the outbreak in that area, we believe it’s important that they get the second dose of AstraZeneca as soon as possible. That is the community that is most at risk in these circumstances.’
 
While the recommendation was directed towards people in COVID hotspots in Sydney’s south-west, the message was not entirely clear to all.
 
Adelaide GP and practice owner Dr Alvin Chua took to Facebook to express his frustration after his reception was inundated with calls from patients looking to book their second vaccination within the new parameters.
 
‘Our receptionist, who hadn’t been able to watch [the news] because she was working, was swamped with phone calls of people asking for their second dose of AstraZeneca, which cannot be given because our bookings are organised well in advance to capacity,’ he wrote.
 
‘Our receptionist has had to work especially hard since the other receptionist quit only a few weeks ago, because it has been one announcement after another.’
 
As it stands, the Australian Technical Advisory Group on Immunisation’s (ATAGI) recommended interval between dose one and two of the AstraZeneca vaccine is 12 weeks, but there is some leeway.  
 
The TGA has reviewed all of the available evidence and determined that the AstraZeneca vaccine can be safely administered 4–12 weeks apart, and ATAGI says shortening the interval from 12 weeks to no less than four weeks ‘is acceptable and may be appropriate in certain circumstances’.
 
‘For example, imminent travel or anticipated risk of COVID-19 exposure,’ ATAGI states.
 
However, there are concerns regarding decreased efficacy when the interval is reduced to a period of less than 12 weeks.
 
A study published in The Lancet found vaccine efficacy reached 81.3% after a second dose in those with a dosing interval of 12 weeks or more, and dropped to 55.1% among those given two doses less than six weeks apart.
 
The move to reduce the time between doses is already in effect in the UK, where health authorities last month changed the maximum interval from 12 to eight weeks after receiving updated advice from the Joint Committee on Vaccination and Immunisation.
 
‘They have recommended reducing the dosing interval to help protect the community from the increasing prevalence of this variant (Delta) and others that may arise,’ the UK’s Department of Health said.
 
‘It’s vital that we move as quickly as possible, with the supplies of vaccine that we have available, to ensure that the maximum number of people receive both doses so that they have fuller and longer lasting protection against the virus.’
 
Other countries, including Canada and Thailand, have also reduced the timing between AstraZeneca doses.
 
Infectious disease and vaccine expert Professor Robert Booy is a proponent of reducing the interval to eight weeks, at least for parts of Australia where transmission risk is higher.
 
‘I’ve been advocating for [this for] more than a month,’ he told newsGP. ‘You may get a better immune response after 12 weeks, but you get an adequately good immune response after eight.
 
‘If it’s good enough for the UK to use eight weeks instead of 12, then it would be great if it could be given at eight weeks by GPs in places like Sydney, where COVID is spreading.
 
‘If transmission is low and unlikely to become a problem, then you can wait that 12 weeks and you get a better immune response.’
 
Commenting on the Prime Minister’s announcement, Dr Chua told newsGP the ensuing confusion has come at a particularly inopportune time, with the past few months of the rollout having been ‘nothing short of frustrating’.
 
But RACGP President Dr Karen Price said the Federal Government’s updated recommendation needs to be seen in the context of the current outbreak affecting Greater Sydney.
 
‘It is our understanding that the Prime Minister’s comments were based on advice from the Chief Medical Officer Paul Kelly and only apply to patients in Greater Sydney,’ she said.
 
‘The decision on how long to wait between AstraZeneca jabs is one that will be made by Greater Sydney GPs in collaboration with their patients on a case-by-case basis. It will depend on a range of factors such as the patient’s medical history and occupation.’
 
Dr Price said this pivot yet again demonstrates why GPs are so fundamental to the vaccine rollout.
 
‘We are skilled and equipped to provide holistic care and consider the patient’s life circumstances,’ she said.
 
‘GPs are not there to tell patients what to do or what not to do. Rather, a GP’s job is to facilitate informed consent for the AstraZeneca vaccine and will base their advice on current ATAGI recommendations.’
 
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