The federal government has a deal for enough doses to vaccinate five million people with the vaccine, which received provisional approval earlier in the week.

Pfizer Australia's market access director Louise Graham told a Senate inquiry the company anticipated new negotiations about a further allocation could start in coming weeks.

"The allocation to Australia is 10 million doses. We expect to be in future discussions about the ability to increase that," she told the hearing on Thursday.

Ms Graham revealed it was Pfizer that approached the government about the initial deal in June last year ahead of the agreement being finalised in December.

Pfizer Australia medical director Krishan Thiru said the company was on track to deliver vaccines in time for the first jabs to be administered in late February.

He denied reports the European Union had slapped export controls on vaccines to be exported outside of the economic bloc.

"Our understanding is it's not an export control, it's a notification process on where doses are going outside of Europe," Dr Thiru said.

"It's obviously critical that governments do not impose export restrictions that could potentially disrupt supply."

AstraZeneca is due to deliver 1.2 million doses from Europe before CSL pumps out a further 50 million in Melbourne throughout the year.

AstraZeneca Australia market access director Alice Morgan said the imports were on track to arrive in late February or early March despite concerns in Europe.

"I would acknowledge it is a fluid situation and there are factors which could be out of our control," she told the hearing.

Acting Chief Medical Officer Michael Kidd has confirmed AstraZeneca's timetable to produce vaccine doses in Australia is running ahead of schedule.

"This supply is now projected to commence in late March, earlier than previously expected, delivering one million doses per week," Professor Kidd told reporters in Canberra.

"It is projected that two million domestically produced doses of the AstraZeneca vaccine will be supplied in late March."

Dr Thiru also explained why Australia would wait up to six weeks for Pfizer vaccinations to start when other countries had rolled out days after approval.

Samples from the batch need to be sent to the Therapeutic Goods Administration for approval before the remainder of the doses are sent.

"The overall process takes a few weeks," Dr Thiru said.

Both companies are confident vaccines can be quickly updated to combat new strains.

CSL knocked back invitations to appear at the hearing, saying it was too busy, despite the committee considering its evidence essential.

New polling shows four in five Australians are willing to be vaccinated, with men keener than women to receive the jab once it becomes available.

A Roy Morgan survey of 1648 people found 85 per cent of men and 73 per cent of women would be willing to take it.

The overall figure of 79 per cent is two points up from the most recent poll in mid-January, but remains below the high of 87 per cent at the onset of the pandemic.

Australian Associated Press