The government has committed an extra $1.5 billion for the new vaccines, bringing the total commitment to more than $3.2 billion.

It's a lot of money, but what does it actually mean, and when could Australians expect to be lining up for a jab?

In the latest announcement, the government has signed two deals for 50 million doses of two different vaccines.

The first is with Novavax for 40 million doses of its protein-type vaccine, which is expected to need two doses to be effective.

Protein-type vaccines are the most common type of vaccine, and this is the second protein-type vaccine candidate the government has signed up for.

The second vaccine candidate the government announced it had signed a deal for on Thursday is one developed by Pfizer and BioNTech. It's what is called a mRNA vaccine, and Australia has made an initial deal for 10 million doses.

This type of vaccine has never been successfully developed before, and the technology to manufacture it doesn't yet exist in Australia, so it would be manufactured elsewhere then transported here.

Health Secretary Brendan Murphy, who heads up Australia's Government Scientific and Technical Advisory Group on Vaccines said the 10 million doses may only be the first batch.

"As part of a diversified strategy we thought 10 million of this vaccine would be a good first option if this turns out to be the most successful vaccine but obviously there's a capacity to buy more and there is the capacity, we are exploring the potential of whether we could set up local manufacturing," he said.

"But that isn't a prospect at the moment. It's something being looked at."

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Before this week Australia had already signed up for two other types of vaccines, one under development from Oxford University and AstraZeneca, which is an adenoviral vaccine and is in phase three clinical trials.

Australia has signed up for 33.8 million doses of that vaccine, some of which would be shipped from overseas, but the bulk of which would be manufactured at CSL in Melbourne.

The biggest deal Australia has signed so far is for a homegrown vaccine candidate - 50 million doses from the University of Queensland, also in partnership with CSL. That's not just patriotism though, the vaccine is in phase three trials and is one of the more promising vaccine candidates in development.

All the vaccines Australia has signed up for are likely to require two doses per person to be effective.

It may seem odd to sign contracts for the supply of products which haven't yet been proven to work, but that is exactly why Australia and other countries are signing multiple deals for different vaccines.

All of the vaccine candidates Australia has signed deals for are in different stages of clinical trials, which is where larger and larger groups of people are given the vaccine to measure whether it works, whether it is safe, and how effective it is.

It could be possible that these vaccines don't provide a lifetime of protection, but need boosters later on, like the yearly flu vaccine.

Because all of these vaccine candidates are still in trials, there is still a chance that one or more of them may be unsuccessful, so the government is being prepared for that.

"We still have to see which vaccine works better in which population and how effectively but we have not put all our eggs in one basket," Professor Murphy said on Thursday.

"We have diversified our strategy and we have the capacity now to start vaccinating the Australian population in the first quarter of next year, which is a terrific outcome and gives us a very, very strong position internationally in access to vaccines."

The four vaccine candidates Australia has made deals for are among dozens of vaccine candidates being developed all over the world. The government has also signed up to the international COVAX facility, which gives countries access to a portfolio of vaccines without having to sign direct agreements like those Australia has already made.

Health Minister Greg Hunt on Thursday said the government had "guidance" but not a guarantee, that the first doses of a vaccine would be available in March next year. That doesn't mean that the whole population will be getting a vaccine for Easter.

Priority will be given to those considered most vulnerable to coronavirus.

"That would start, not surprisingly, with health workers and the elderly, if there are approvals within the particular vaccine categories following the tests for the elderly," Mr Hunt said.

"But it's absolutely clear that we're on a path to having vaccines for all Australians during the course of 2021."

As well as signing deals with multinational pharmaceutical companies, the government is also thinking about how a successful vaccine would move around Australia and where people would go to get a jab.

Mr Hunt says the government has released tenders for the transportation of vaccines, and the successful candidates will need to be able to meet requirements for vaccines that need to be kept at temperatures varying from 2-8 degrees, -20 degrees, and even as low as -70 degrees.

The federal Health Department is also talking to industry peak bodies and state and territory governments to work out vaccination locations. Places like GP clinics and pharmacies are likely to play big roles for the mass vaccination of the population.

While it feels like the development of these vaccines is happening at warp-speed, the government has assured that corners are not being cut.

Any vaccine that completes its clinical trials will still need to be approved by the Therapeutic Goods Administration, just like any drug that is available in Australia.

"The TGA will play an absolutely essential role in assuring all Australians that the vaccines that will be made available will be safe and they will be effective," Prime Minister Scott Morrison said on Thursday.

The government has also committed to every Australian being able to be vaccinated for free, and that vaccination won't be compulsory.

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