Medical experts have reassured Australians any coronavirus vaccine will be developed with world-class ethical standards in mind, as religious leaders voice concerns.
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.
Three senior Sydney clerics - Catholic Archbishop Anthony Fisher, Anglican Archbishop Dr Glenn Davies and Greek Orthodox Archbishop Makarios - have written to Prime Minister Scott Morrison questioning the ethics of supporting a vaccine that makes use of a cell line cultured from an electively-aborted human foetus.
The letter says the use of such techniques will "raise serious issues of conscience" for many Australians.
"Those troubled by this may either acquiesce to the social and political pressure to use the vaccine, or conscientiously object to the use by themselves and their dependents," they wrote.
They sought assurances from Mr Morrison that the vaccine would "in no sense be mandatory", that no one would be pressured to prescribe, dispense or consent to the use of it and that an "ethically uncontroversial alternative vaccine" would be made available.
Deputy chief medical officer Nick Coatsworth told reporters he was aware of the concerns.
"The reality for the vaccines is that they need cell cultures in order for us to grow them," he said.
"Human cells are really important part of their development."
He said there were "strong ethical regulations" surrounding the use of any human cell, particularly foetal human cells.
"This is ... one of the world's leading universities, so I think we can have every faith that they have manufactured the vaccine against the highest of ethical standards internationally."
Labor frontbencher Jim Chalmers said when a vaccine was available as many people as possible should be vaccinated to ensure it is effective.
"That's my personal view. I say that as a Catholic. That's the best outcome for Australia," he told the ABC.
"The vaccine is what will get us to the other side of this diabolical health problem with all the economic consequences it brings."