Victoria's cluster of cases has climbed to 15, with authorities naming dozens of exposure sites including the MCG where an infected person attended an AFL match on Sunday.

Melbourne may soon enter another snap lockdown to bring the outbreak under control.

Liberal senator Jane Hume is concerned three Victorians at the centre of the cluster were not vaccinated despite being eligible.

"The most important thing for Victorians is they get out and get themselves vaccinated," she told reporters in Canberra on Wednesday.

"We heard that of the new cases that were announced overnight and yesterday as well, three of them were over 50 that could have been vaccinated, so that increases the urgency to get the vaccinations done."

The federal government does not know how many Victorians infected in the latest outbreak have been vaccinated.

There are widespread concerns about the sluggish pace of the national vaccine rollout.

Home Affairs Minister Karen Andrews denied depleted stock levels were to blame for Australia lagging behind other nations.

"There are adequate supplies at this point so please go out and get vaccinated," she said.

Labor is urging the government to redraft vaccination plans and scrap its staggered program for getting a jab.

Just under 3.8 million doses of coronavirus vaccine have been administered across the country, well short of initial targets.

State and territory governments have defied the tiered approach to the vaccine rollout and opened eligibility to new cohorts ahead of the federal government.

The latest outbreak has also raised fresh concerns about the country's reliance on hotel quarantine, which has repeatedly faltered throughout the pandemic.

The Melbourne flare-up has been linked to a man who caught the virus while in hotel quarantine in Adelaide.

Prime Minister Scott Morrison ducked multiple questions on whether Australians would be safer if he had created a national, purpose-built quarantine system.

Mr Morrison tried to reframe the Question Time interrogation as an attack on the South Australian government, claiming he would not attack the states.

The prime minister has regularly criticised state governments over border closures and lockdowns throughout the coronavirus pandemic.

Mr Morrison also accused Labor of being "whingers and complainers" for questioning the vaccine rollout, claiming voters stop him in the street to say how well Australia has done compared to other countries.

Labor health spokesman Mark Butler said the prime minister should be moving faster to fund state proposals for purpose-built quarantine sites.

"We can't continue to see these outbreaks from a quarantine system based around hotels, which were built for tourism, not medical quarantine," he said.

"We don't have national standards still in our hotels around ventilation, around the use of personal protective equipment. We still have staff in our hotels doing quarantine who haven't been fully vaccinated."

Ms Andrews said the Commonwealth was doing its due diligence on a Victorian quarantine proposal but could not put a timeline on when a decision would be made.

"This is a very important proposal that has been put forward. It is a comprehensive proposal, which is excellent - that's what we need," she said.

New restrictions have been imposed across Melbourne, including mandatory mask-wearing indoors and limits on gatherings, but the state government has so far resisted a lockdown.

States and territories have tightened borders with Victoria but stopped short of complete closures.

Australian Associated Press