Australia's medicines regulator has suggested it is unlikely two deaths in NSW were linked to coronavirus vaccinations.
Therapeutic Goods Administration head John Skerritt said investigations were underway after two men, 55 and 71, reportedly died from blood clots.
It is believed both received the AstraZeneca jab, which is recommended for use only in people over 50 because of extremely rare but serious blood clots.
Adjunct Professor Skerritt said the men had various blood clots but declined to provide more detail on privacy grounds.
He strongly cautioned the media and public against reaching any conclusion about the deaths and potential links to vaccination.
"The current evidence does not suggest a likely association," he told reporters in Canberra on Thursday.
The TGA boss stressed the regulator was not seeing a flood of serious adverse reactions with just 11,000 reports from 2.1 million doses ranging from sore arms to heart attacks.
All serious incidents are carefully scrutinised with the rate of blood clots linked to AstraZeneca still around five in every one million shots.
"The benefits dramatically exceed the risks, so knowing there is a small background risk of clots is something not to hide," Professor Skerritt said.
"But all medicines, all treatments, all procedures, driving a car, flying in a plane, have some risk and in the case of these vaccines the benefits outweigh the risks."
Prime Minister Scott Morrison also urged caution about linking blood clot deaths to vaccines without proof from medical experts.
"We've got to be careful about how we talk about these cases," he told Darwin radio Mix 104.9 on Thursday.
"Let's allow the medical facts to be established."
The prime minister's cautious tone comes as the government and health experts try to fight rising vaccine hesitancy.
Chief Nursing Officer Alison McMillan said stringent processes were in place to investigate adverse reactions.
"It's really important not to jump to conclusions here," she told the ABC.
The TGA has confirmed six cases of rare blood clots that are likely linked to the AstraZeneca vaccination.
While there is advice it not be used in people under 50, the side effect is extremely rare with between four and six cases for every one million jabs.
Victoria is putting the heat on the federal government to stump up cash for a new quarantine facility in Melbourne's north.
Mr Morrison, who met with tourism industry chiefs in Darwin, said options to bring more overseas workers and international students to the NT were also being canvassed.
"It would have to be a partnership with the commercial sector," he said.
He said setting up specific quarantine facilities like at Howard Springs near Darwin needed to consider infection control, workforce, security and flights.
"It's not just about finding a mining camp with some beds. It's much more complicated than that," the prime minister said.
Labor continues to pressure the coalition government to boost hotel quarantine and take charge of more federally run centres.
Australian Associated Press