CMO wades into AstraZeneca, Pfizer vaccine debate saying 'choice is not whether one is better than the other'

| 13.01,21. 06:51 PM |

CMO wades into AstraZeneca, Pfizer vaccine debate saying 'choice is not whether one is better than the other'

The AstraZeneca vaccine can be manufactured in Australia and will be available throughout the year, according to the Federal Government.(Reuters: Gareth Fuller)

CMO wades into AstraZeneca, Pfizer vaccine debate saying 'choice is not whether one is better than the other'

The AstraZeneca vaccine can be manufactured in Australia and will be available throughout the year, according to the Federal Government.(Reuters: Gareth Fuller)

Chief Medical Officer Paul Kelly says the Federal Government is choosing to roll out the safe and effective COVID-19 vaccines it has available after some scientists questioned Australia's plan to widely distribute the AstraZeneca vaccine rather than the Pfizer drug.

"The choice is not whether one is better than the other, it's which one is available to give the maximum rollout of vaccine to save lives and to protect lives this year," he said.

"The answer to that is the one we can make here."

Debate has raged today after a media report quoted the president of the Australian and New Zealand Immunology Society (ASI) as saying the group supported pausing the rollout of the AstraZeneca vaccine in favour of the reportedly more effective Pfizer vaccine.

However, this afternoon the society distanced itself from its president's comments, saying it did not call for such action and the AstraZeneca vaccine was an "important advance" in combating COVID-19.

The debate over the use of the AstraZeneca vaccine as a key component in Australia's COVID-19 vaccination strategy centres on the effectiveness of the drug.

At this stage, the reported effectiveness of the AstraZeneca vaccine is about 70 per cent, while the Pfizer inoculation is reported to be 95 per cent effective.

Importantly, the Pfizer drug is in limited supply, but the AstraZeneca vaccine can be made locally in the quantities required to vaccinate the entire population.

The plan for Australia is to have vulnerable populations vaccinated with the 10 million doses of the Pfizer vaccine the Government has been able to secure and use the AstraZeneca vaccine to reach everyone else.

Professor Kelly said the AstraZeneca vaccine was essential to Australia's strategy because "we don't need to queue" for it.

"It will save lives," he said.

"We don't have the ability to make mRNA vaccine onshore. We have made the ability to make the AstraZeneca vaccine, as a different version of essentially getting to the same end point."

Infectious disease expert Allen Cheng tweeted about the debate, saying "the choice we have isn't whether to use one vaccine or the other".

"Our choice is whether to offer everything we have now to protect as many people as we can, or to leave some effective vaccines in the warehouse," he said.

AstraZeneca data incomplete
There is still much more to learn about the effectiveness of the AstraZeneca COVID-19 vaccine.

In the phase three trial of the drug, there were effectively two parts of the study.

One group was given a low dose of the vaccine, followed by a high dose. The people in that group showed an efficacy of 90 per cent.

In the main arm of the study, which used the two regular doses of the vaccine, a high dose followed by another high dose, the effectiveness was 62 per cent.

The Therapeutic Goods Administration (TGA) is yet to approve any COVID-19 vaccine for use in Australia and is awaiting complete phase three clinical trial data on the AstraZeneca drug.

Once the TGA has complete data, it will make a decision about the vaccine's approval and the dosage protocol.

Only then will the Government and scientists have a clear picture on the efficacy of the AstraZeneca drug we can expect in a vaccinated Australian population.

Scientists are hopeful the full results of the phase three trials will reveal a higher rate of effectiveness for the AstraZeneca drug.

"We have had three more months of data that will be available to the TGA and more data from the real world information that's coming from the UK who are already rolling out that vaccine," Professor Kelly said.

He said the Government would take advice from its own expert medical group, known as the Australian Technical Advisory Group on Immunisation, about which vaccines to use here.

Viral immunologist from Monash University, Professor Stephen Turner, is the president of the ASI and said his opinion on the AstraZeneca vaccine differs to that of the society he represents.

"There's just a question of whether it should be the only vaccine going forward," he said.

"It's not that the AstraZeneca vaccine doesn't induce an immune response, the question is whether it will induce immunity that will be able to provide herd immunity.

"Until we know more, I'd like to see plans around deployment of the Pfizer vaccine more widely."

There are no questions about the safety of the AstraZeneca vaccine or that it should be part of the suite of vaccines Australia offers.

While some scientists have raised concerns about the lower effectiveness of the AstraZeneca vaccine, others say there is a path to herd immunity.

Australia's path to herd immunity
Herd immunity occurs when the vaccination of a significant portion of the population provides protection for those people who have not developed immunity.

It happens when a high percentage of people are protected through vaccination, making it difficult for a virus to spread because there are so few susceptible people left to infect.

Heidi Drummer from the Burnet Institute said the AstraZeneca vaccine was a "really fantastic vaccine in preventing severe COVID-19 infection".

Dr Drummer said the path to herd immunity was "a simple mathematical equation" and if Australia was only using the AstraZeneca drug at 62 per cent efficacy, "we will have difficulty reaching herd immunity".

"If you need 70 per cent of the population to be immune from COVID-19, it would mean that you would need to vaccinate every single person in Australia with that vaccine, to even get close to herd immunity," she said.

Dr Drummer said the Government's plan to roll out the Pfizer vaccine — which has 95 per cent effectiveness— along with the AstraZeneca jab could help achieve herd immunity.

"Together, the use of those two vaccinations across the populations may get us to a herd immunity level, but that requires a deeper discussion about who receives which vaccine, which is a difficult question to think about," she said.

Using the Pfizer vaccine first, on the most vulnerable groups in Australia, does give health experts some time to look at the latest data available on the AstraZeneca vaccine.

"The fact they were able to achieve a really high rate of efficacy of 90 per cent, I am hopeful they will find that higher rate of efficacy in the phase three trials they were doing," Dr Drummer said.

Pfizer rollout restricted by supply
The question of whether Australia should be using the Pfizer vaccine more is ultimately answered by the fact that drug is not readily available.

In negotiation, the Pfizer vaccine manufacturers offered the Australian Government 10 million doses, which are due to be delivered.

There is the potential to get more via the COVAX agreement, but that is not guaranteed.

What can be relied on is the supply of the AstraZeneca vaccine that will be made locally and the Government is keen to ensure the public's confidence in that drug.

Social scientist Associate Professor Holly Seale studies the public's perception of vaccines and said research shows about 80 per cent of Australians are willing to get a COVID-19 vaccine.

"Amongst members of the community, there is agreeance that they will want to roll up their sleeves and go and get vaccinated," she said.

"That is at a higher starting point than what we are seeing in other countries."

But she warns we should not take our eye off the ball as there are many influences on people's willingness to be inoculated.

"One of the key ones is healthcare workers actually making a recommendation around the vaccine," Dr Seale said.

In her view, it is important that primary care providers, doctors and nurses, as well as specialists, understand how the different efficacies of the various vaccines are being used within Australia's overall strategy, so they can communicate that information to patients.


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