Australia's vaccine rollout and the emergence of new coronavirus strains will be crucial to the federal government's decision to restart international travel.
Qantas boss Alan Joyce is hopeful borders will reopen in October which is the target for the population to have at least one jab.
But Finance Minister Simon Birmingham struck a cautious note in responding to the lofty travel goal on Friday.
"There are many uncertainties between now and October," he told Sky News.
He is hopeful Mr Joyce's target can be achieved but warned more evidence about vaccine protection against emerging strains in the UK, South Africa and Brazil would be needed.
"We'll have to continue to be guided by the science and the health advice in terms of the protections the vaccines will offer," he said.
Senator Birmingham said the vaccine would change the risk profile as quarantine and frontline health workers were immunised.
"All of those different steps reduce the risk for the Australian population overall," he said.
"Hopefully that will enable everybody to make decisions to keep things a little more open over time and ultimately see us take that leap to reopen international borders."
Qantas posted a $1.47 billion statutory loss for the six months to December and a $6.9 billion fall in revenue due to pandemic restrictions.
Mr Joyce said the airline was planning international travel to restart at the end of October when the vaccine rollout is due to be effectively complete.
"We're confident that there should be a good case for it opening up in October," he said.
With JobKeeper wage subsidies set to end in a month, Senator Birmingham flagged an announcement about sector-specific relief packages, including for aviation, in coming weeks.
"What we want to do is limit as much as we possibly can limit the degree of taxpayer support," he said.
"But we do realise there will be some targeted support necessary.
"Obviously the aviation sector is one that has very strong and credible arguments as to how the continue border restrictions and impacts of COVID play out for them."
Australian Associated Press