PERTH, Australia – The Australian government is recommending that Australians under 50 take the Pfizer Inc. COVID-19 vaccine due to the risk of rare blood clots associated with Astrazeneca plc’s COVID-19 vaccine (ChAdOx1-S).

The move jeopardizes Australia’s vaccine rollout as it had planned for the majority of Australians to receive the Astrazeneca vaccine, which is being locally manufactured by CSL Ltd.

During a press conference announcing the local manufacture of the vaccine in March, officials were gloating about what a fabulous job the country had done in fighting the COVID-19 pandemic. Now it looks as if it is falling behind on vaccinating its citizens, and Prime Minister Scott Morrison said that essentially “all bets are off” on whether Australians will be vaccinated by the end of the year. Previously, he had said that all Australians would be vaccinated by October.

The TGA granted provisional approval to the overseas-manufactured Astrazeneca vaccine in February. Initial supply of the vaccine was imported into Australia, and ongoing supply is being manufactured in Australia. CSL has a contract to manufacture 50 million doses of the Astrazeneca vaccine, which the majority of Australia’s population will receive.

The TGA cleared Pfizer Australia Pty Ltd.’s COVID-19 vaccine, branded Comirnaty, in January, and most front-line workers have received the Pfizer vaccine as part of Australia’s phase IA rollout.

Risk of blood clots prompts recommendations

The recommendations for people under 50 to opt for the Pfizer vaccine came from the Australian Technical Advisory Group on Immunization (ATAGI) based on the rare risk of blood clots associated with the Astrazeneca vaccine. The EMA concluded that the benefit of the Astrazeneca vaccine outweighed the risk.

Older Australians are being encouraged to go ahead and get the Astrazeneca shot, and the country has so far vaccinated more than 1 million people, Morrison told reporters during a press conference late April 9.

Australia has a federal vaccination policy that is decided in partnership with the National Cabinet that is composed of the prime minister, state and territory premiers and chief ministers. The National Cabinet voted to follow the ATAGI recommendations.

Subsequently, Australia secured an additional 20 million doses of the Pfizer-Biontech SE COVID-19 vaccine, which should arrive on Australian shores in the fourth quarter, Morrison said.

“Through our advanced purchase agreement with Pfizer, these additional 20 million Pfizer doses means that Australia will now receive a total of 40 million Pfizer doses in 2021, he said.

Australia has entered four separate agreements for the supply of COVID-19 vaccines, and those include agreements with Pfizer, Astrazeneca, Novavax Inc. and COVAX.

“We already had 20 million Pfizer doses which had been committed for delivery in 2021, and this brings an additional 20 million doses on top of the Novavax 51 million, the Astrazeneca 53.8 million and the COVAX facility 25.5 million, taking it to a total available pool of 170 million doses,” Health Minister Greg Hunt said.

Australia is in the process of vaccinating people over the age of 70 and Indigenous Australians over the age of 55. Once that group is vaccinated, it will turn to the over 50 age group, which will also receive the Astrazeneca vaccine.

“For those who may be immunocompromised or front-line workers who are under 50, then right now we’re working with the states and territories and the medical authorities to revise that part of the program, so they have access to [the Pfizer vaccine]. That will take time,” Hunt said.

One of the recommendations from ATAGI was to make sure that that the informed consent process was updated to reflect the new information, and the states and territories have made these changes, said Chief Medical Officer Paul Kelly.

When asked why the government didn’t procure supply from Johnson & Johnson and Moderna Inc., Morrison said that the government followed the advice of the scientific advisory group.

Department of Health Secretary Brendan Murphy said that the Scientific and Technical Advisory Group “strongly recommended that we have a stake in the mRNA vaccine, and we went with Pfizer mainly because of its capacity to deliver and it was not a new company.

“And experience has shown that they have delivered a lot more vaccine than Moderna. Had we had a contract with Moderna we would have had not very much delivered at this time.”

He said the government is also in discussions with J&J, noting that both the J&J and Astrazeneca vaccines are adenovirus vector vaccines.

“We still don't know what the cause of this adverse effect is, whether it relates to just this vaccine or other adenoviruses. We have to wait and see, so at the moment we are still exploring with Johnson & Johnson as we have with every other company. But every single recommendation of the Scientific and Technical Advisory Group that has been made to government has been accepted,” Murphy said.

“We have been in the fortunate position, just as Professor Murphy has shown with the ramp up, because we have had Astrazeneca with home-grown production through CSL allowing us to ramp up that supply earlier…. In terms of the investment, our total investment in vaccines alone is over $4 billion and our total investment in the vaccine program is now over $7 billion,” Hunt said.