Australia is considering the latest advice on the AstraZeneca vaccine from Britain and the European Union, pertaining to the rare link with blood clots.
Restrictions on the AstraZeneca vaccine could be imposed after a link was confirmed between the jab and rare blood clots.
European authorities have identified the link, prompting the United Kingdom to offer people aged under 30 an alternative vaccine due to the risk.
Other countries are considering attaching warning labels.
Australia's drug regulators are holding urgent meetings to consider the findings before providing the government with recommendations.
Health Minister Greg Hunt emphasised the regulators would offer independent, frank and fearless advice.
"If they provide age restrictions or other variations, we'll do it. We'll adopt it," he told reporters in Melbourne on Thursday.
The European Medicines Agency has not made a specific recommendation, but found women and people under 60 were at a higher risk of developing the rare side effect.
The advice could pose a significant threat to Australia's vaccine strategy, given most Australians are set to receive the AstraZeneca jab.
Chief Medical Officer Paul Kelly said the AstraZeneca vaccine was effective and very safe for most people.
"There is this extremely rare event which appears to be associated with that particular vaccine in some people - four per million," he said.
"The benefit is that the vaccines are very effective at preventing COVID illness that can be severe and lead to deaths, particularly in older people."
Prime Minister Scott Morrison said it was too early to say whether Australia would follow other countries in adding warning labels to the AstraZeneca vaccine, or giving people aged under 30 a different drug.
But he said the risk of blood clotting was far higher among women taking contraceptive pills, and even from common paracetamol tablets.
The prime minister said there was nothing to suggest the national vaccine rollout would be affected at this stage, particularly given the early phases were focused on older Australians.
The federal government has asked its immunisation advisory group and the national medicine regulator to review the recommendations.
The findings will also be discussed among state and federal health ministers and at the next meeting of national cabinet on Friday.
More than 996,000 coronavirus vaccine doses have now been administered.
Federal Opposition Leader Anthony Albanese said the advice on AstraZeneca highlighted the danger in Australia failing to secure vaccine deals with other suppliers.
Mr Albanese said the government had a full year to prepare for the vaccine rollout.
"Australians are worried. Australians deserve better than a 'she'll be right mate' approach," he told reporters.
Nationals senator Matt Canavan also believes the government should be securing more vaccine deals.
"We need to get more of other types of COVID vaccines so we can offer a choice just like the UK are doing for young people," he said.
Meanwhile, Western Australia is edging closer towards making it mandatory for hotel security workers to get vaccinated.
About a third of the cohort are yet to receive their first dose.
Victoria's hotel quarantine program has restarted for a third time, as the state government ramps up its vaccination program.