AstraZeneca blood clot link increases importance of Novavax

Anastasia Tsirtsakis

8/04/2021 4:32:59 PM

But with clinical trials progressing slowly, uncertainty remains over when Australia will access the 51 million doses of its third vaccine candidate.

Novavax logo
Interim data of the Novavax is promising, with 95.6% efficacy against the original COVID-19 strain.

This article was updated at 9.35 pm Thursday 8 April.

Australian health authorities have ‘recalibrated’ the country’s vaccine plans.

The Australian Technical Advisory Group on Immunisation (ATAGI) announced on Thursday night ‘the use of the Pfizer vaccine is preferred over the AstraZeneca vaccine in adults aged less than 50 years’. 

The decision comes after Australian health experts met to discuss ongoing concerns over the link between blood clots and the Oxford University/AstraZeneca vaccine.

‘We expect that this will require some changes to the arrangements we have as part of the vaccination rollout,’ Prime Minister Scott Morrison said on Thursday night.

‘And this includes when we might expect our first doses, ultimately, to be able to be offered to all Australians.’

However, the Prime Minister was clear the recommendation does not preclude the use of  the AstraZeneca vaccine.

‘This is not a directive. This is not an instruction,’ he said.

Elsewhere, health experts in the UK, EU and at the World Health Organization (WHO) have all indicated there is a higher risk of adverse reactions for younger recipients – particularly women – of the Oxford University/AstraZeneca vaccine.

The possible link between the vaccine and blood clots means people in the UK under 30 will be offered an alternative, provided they do not have underlying health conditions that put them at higher risk of severe COVID-19.

Director of Infectious Diseases at Mater Health Services in Brisbane, Associate Professor Paul Griffin, told newsGP he believes this is ‘a sensible decision’, as there appears to be less of a risk–benefit for healthy young people and the UK has access to a number of alternatives.

Australia, however, is in a slightly different position.

While the Federal Government has a contract in place for 20 million doses of the Pfizer/BioNTech vaccine, only 870,000 have so far arrived.

The shortage has meant aged care workers who are part of phase 1a of the vaccine rollout are already being denied crucial second doses, while the reliance on offshore production, along with logistical challenges around transport and storage, raises questions over how soon the candidate could fill the gap.

The third potential vaccine Australia could access in the future is Novavax, for which there is an existing contract for 51 million doses. Interim data also indicates it possesses 95.6% efficacy against the original COVID strain, 86% against the UK variant, and 49% against the South African variant.

If data from ongoing phase 3 trials proves to be just as promising, and it receives Therapeutic Goods Administration (TGA) approval, Associate Professor Griffin says Novavax could be Australia’s answer to the question of an alternative.

But this solution comes with a caveat: it may push back already delayed vaccination targets, as Novavax is currently facing a number of hurdles.

‘They have had some challenges recruiting for their clinical trials, so the progress is perhaps slower than they would have liked,’ Associate Professor Griffin said.

‘I know they’re looking at adding additional sites, for example, to perhaps boost that recruitment. So if that works, then perhaps it’ll be a bit sooner, but I think the latter part of the year looks most likely.’

That delay notwithstanding, Associate Professor Griffin believes positive phase 3 trial results will still leave Australia in a ‘really strong position’.

‘AstraZeneca still very clearly has a role,’ he said. ‘As every day passes we’re understanding more and more about these complications and perhaps we’ll [soon] have a way of screening for people at higher risk, for example, so that we can then be more confident in still using that vaccine. 

‘But with Novavax we have a good purchasing agreement for a very large number of doses, and if the clinical trial data proves it’s as safe and successful as it looks like then that could certainly be a vaccine that helps us a lot in this country.’

Associate Professor Paul Griffin believes it is vital clinicians and the public understand the risks associated with Australia’s current main vaccine, AstraZeneca, remain ‘incredibly low’.

In the meantime, Associate Professor Griffin believes the key is to ensure clinicians and the public understand the risks associated with Australia’s current main vaccine, which he says remain ‘incredibly low’.

While the risk for blood clots is said to be as low as four in one million for recipients of the Oxford University/AstraZeneca candidate, there are ongoing fears about the impact recent reports will have on vaccine uptake.

New research by the Australian National University has found young women aged 18–24 are already the most reluctant group in Australia to get vaccinated, with only 43% saying they are willing to get vaccinated as soon as possible compared to 62% of men of the same age. However, the women said their decision could change depending on their confidence in government.

So far, 79 cases of vaccine-related blood clotting with low platelet count were recorded in the UK. And of the more than 20 million people who have received the Oxford University/AstraZeneca COVID vaccine in the UK, young women appear to be the most affected.

The European Medicines Agency (EMA) has also released its own statement confirming a possible link between the vaccine and 86 reported cases of blood clotting in the EU, while the WHO is requiring AstraZeneca to list blood clots as a possible rare side effect of the vaccine.

ATAGI and the TGA have been working with international authorities to investigate the issue of thrombosis after a 44-year-old man in Melbourne was hospitalised with blood clots just over a week after being vaccinated.
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Dr Thonse Sheenappa Prasad   9/04/2021 8:45:09 AM

lost my last email!
could i choose to have the Pfizer vaccine instead of the AZ,
as i have been commenced on NOVAC, & my wife suffered
from a DVT & a PE following a TKR surgery.
could you please advise?

Dr Dariush Fatehee-Brujenee   9/04/2021 12:55:38 PM

having PMH:DVT+PE dosen't increase the risk of blood colt from AZ vaccination, the only condition that has been advised not to have AZ vaccination is:1-CSVT 2-heparin induced thrombocytopaenia, this very rare side effect has mostly affected the people under the age of 30, obviously from your history of TKR your age should be around
70 still AZ is good for you.

Dr Daisy Mehra   9/04/2021 8:01:10 PM

Hi Dr Paul
As the AZ vaccine being avoided in people less than 50, what should people who have had 1 dose od AZ, can they go for Pfiozer vaccine?

Dr Yulya Gorovy   10/04/2021 2:06:32 PM

The female 56 y.o. patient with Glyoblastoma on immunotherapy drug Avastin-what the best COVID vaccine choice ?