The federal government is maintaining confidence in the AstraZeneca vaccine despite its use being suspended in parts of Europe.
Denmark, Norway and Iceland have temporarily stopped using the vaccine while authorities investigate whether it is linked to blood clots.
Prime Minister Scott Morrison said Australian authorities did not share their concerns.
"That is not the view of our medical advisers," he told reporters in Sydney on Friday.
Europe's medical regulator is reviewing the issue, with initial indications that the number of people experiencing blood clots after the vaccine is the same as in the general population.
There have been 22 cases of blood clots in the three million people vaccinated with the AstraZeneca jab in Europe.
Julie Leask from Sydney University's school of nursing and midwifery says countries have different approaches to reports of adverse events, with some being extremely cautious while others investigate while continuing the rollout.
"These are the dilemmas that leaders face when vaccine safety events occur," Professor Leask said.
"When vaccines are suspended due to such events, it can take a while for public confidence to return, even if the problem is later found to be unrelated. So these are never easy decisions."
Meanwhile, Mr Morrison sought to correct the record on the government's aim to have the entire Australian population vaccinated by October.
"The first dose to be administered by October - that's what I meant," he said.
"We were clear a month ago that the October deadline would not include the second dose."
The prime minister said the move from four weeks to 12 weeks between recommended doses had blown out the promised timeline.
"This is not news," Mr Morrison said.
"As we continue to update, it's important to stay up-to-date on where the goal posts are on this."
He defended the sluggish speed of the early-stage rollout.
The government initially promised to have four million people vaccinated by the end of March.
But so far only 125,000 have received their first jab.
Mr Morrison blamed international supply blockages for the delay, but said the fact Australia still manage to secure 700,000 doses out of Europe was a Herculean effort.
He anticipates the rollout to pass 150,000 injections by the end of this week.
Shadow treasurer Jim Chalmers said it was clear the prime minister had over-promised and under-delivered.
"Very clearly the government has dropped the ball on vaccines," Dr Chalmers said.
Mr Morrison also leapt to the defence of Department of Health secretary Brendan Murphy, after he told a Senate committee one coronavirus jab offered full protection against the disease.
Professor Murphy later clarified his evidence, saying one dose was "fully protective" but needed to be topped up.
"You must get two doses," the prime minister said, before seeking to clarify the official's remarks.
"What he's saying is the first dose is a good dose. The first dose actually provides quite an effect. But the course of those doses is to have two."
Australian Associated Press