January

* European Commission introduces export controls

* AstraZeneca provides advice to government that only 1.2 million of the 3.8 million doses contracted to Australia could be delivered in February (500,000) and March (700,000)

* Vaccine shortages and increasing export restrictions cited for shortfall

February

* Australia applies for export licences for 500,000 doses instead of 3.8 million

* Health Minister Greg Hunt calls European Union counterpart to ask for 500,000 doses to be released

* AstraZeneca told to withdraw application and resubmit a request for 250,000 instead

* On the same day, EU advises Morrison that 500,000 doses will not be approved because more time was needed. Morrison agrees

* Application for 250,000 doses submitted

March

* EU denies export of 250,000 doses from Italy to Australia

* Hunt asks for decision to be reviewed

* Morrison requests one million doses from Australia's contracted supply to be sent to Papua New Guinea. He says no response has been received

* Hunt asks AstraZeneca to resubmit application to EU

April

* Morrison blames 3.1 million undelivered doses from Europe for slow progress in Australia's vaccine rollout

* EU denies it blocked exports

* Morrison encourages EU to grant export licences for full balance of contracted vaccines, pledging the first one million to PNG

(Source: Prime Minister Scott Morrison's news conference in Canberra on April 7)

Australian Associated Press