Australia signed two deals on Thursday (November 5) to buy 50 million more doses of potential COVID-19 vaccines.
Novavax will supply 40 million of the doses, while Pfizer and BioNTech will provide 10 million.
Thursday's agreements follow deals in September with AstraZeneca and CSL -- worth $1.2 billion.
All four vaccines are leading candidates in the race to get regulatory approval in the United States and Europe.
Announcing the investment, Prime Minister Scott Morrison said Australia would be ahead of the game:
"Now today we are announcing an extra one and a half billion dollar investment in the Novavax and Pfizer vaccines. This adds to our overall program of over three and a half billion dollars that we're investing to ensure that Australians will be in the leading pack of the world as we move into the next phase of dealing with COVID-19, which is the vaccine phase."
Federal Health Minister Greg Hunt added that the government was on track to roll out the vaccines from March next year.
"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 vaccine, so."
Australia has reported just over 27,600 cases of Covid-19, and 907 deaths, far less than many other developed countries.
The majority of cases have been reported in the hotspot state of Victoria. But the state reported no new cases for the sixth straight day on Thursday.