Australian Prime Minister Scott Morrison announced the doses would be sent immediately, along with other critical care equipment.
Papua New Guinea's fragile healthcare system is under huge strain.
Officially, there are 1,400 active cases in the country, but the true number is thought to be much higher.
Testing has been an issue for the island nation. As of 10 March, only 50,000 tests had been carried out in a country with a population of nine million.