Australia has reached a supply agreement for 25 million doses of Moderna COVID-19 vaccines, the US-based biotechnology company and the prime minister said Thursday.

The deal included 10 million doses of the vaccine against the ancestral strain to be delivered in 2021 and 15 million doses of an updated variant booster to be delivered in 2022, Moderna said in a statement.

The vaccines have yet to be approved by the Australian regulator, the Therapeutic Goods Administration. Pfizer and AstraZeneca are the only other coronavirus vaccines approved for use in Australia. All three vaccines require two doses.

Prime Minister Scott Morrison said he expected the first Moderna vaccines to arrive in Australia in the last three months of 2021.

The 15 million booster doses would deal with possible future variants of the virus, he said.

“We're now well into the phase of dealing with what's coming next because the pandemic's not going anywhere,” Morrison told Perth Radio 6PR.

Moderna vaccines would help Australia achieve its aim of inoculating all willing Australian adults within a population of 26 million by the end of the year.

Australia has contracted 20 million imported Pfizer doses, which is the preferred option for adults under 50 years old because of the blood clotting risks associated with the AstraZeneca shot. The government also has deals for 3.8 million imported AstraZeneca doses plus 50 million locally manufactured doses.

Morrison said it was likely the Moderna vaccines would be recommended for Australians under 50.

Jane Halton, a director of the Australian National COVID-19 Coordination Commission, welcomed the Moderna deal. She said the government should consider manufacturing Moderna vaccines onshore, although building the facilities would take more than a year.

The vaccine rollout began in February, and the government had expected to administer 4 million doses by the end of March. But only 2.8 million doses had been injected by this week, with the government blaming slow shipments for delays.

Australia has been relatively successful in containing the virus. While 910 have died of COVID-19, the government argues the death toll would be 30,000 higher if Australia's fatality rate was the average of Organization for Economic Cooperation and Development countries.