Scott Morrison, who is a practicing Christian, said his family would take the vaccine if it proves successful, despite scientists using cell lines from an electively-aborted foetus.

Catholic, Anglican and Greek Orthodox church leaders have expressed concerns about the vaccine being developed at Oxford University.

The three senior Sydney clerics sought assurances it would not be mandatory and nobody would be forced to prescribe or dispense it.

They also urged the prime minister to ensure an "ethically uncontroversial alternative" would be made available.

Mr Morrison said he was respectful of and sensitive to their views but would get the vaccine and recommend it to others once it cleared all clinical trials.

The prime minister pointed out the cells being used were cloned from others dating back to the 1970s.

"So it's not current cells that have been taken from abortions or anything like that, this is stuff going back 40 years," he told 2SM radio on Friday.

"And there are many vaccines at the moment that are out there currently in widespread use which draw on that."

Mr Morrison said his job was to weigh religious objections against the public interest.

"In this case, given the concerns relate to things that happened 40 years ago, it's not a current practice, personally I am comfortable with that," he said.

"But I mean, these are personal judgments that people make and you've got to always be respectful of other people's views."

Australia has signed a letter of intent with vaccine developer AstraZeneca and Oxford University to manufacture and distribute a COVID-19 vaccine, should the trials prove successful.

Cells derived from elective abortions have been used since the 1960s to manufacture vaccines against rubella, chickenpox, hepatitis A, and shingles.

They have also been used to fight diseases including haemophilia, rheumatoid arthritis and cystic fibrosis.

Australian Associated Press