Australia is a victim of its own success as it plans a strategy for the next phase of dealing with the coronavirus pandemic, according to Deputy Chief Medical Officer Professor Paul Kelly, who ruled out a herd immunity approach adopted by other nations.

Key points: Professor Kelly said a herd immunity wouldn't help Australia with its next steps

Professor Kelly said a herd immunity wouldn't help Australia with its next steps Without a vaccine, he said that a second wave of COVID-19 was likely

Without a vaccine, he said that a second wave of COVID-19 was likely Professor Kelly said states and territories must make their own decisions about easing restrictions

Herd immunity is when a large proportion of the population becomes infected with a disease, but many recover and become immune to it.

Speaking to reporters in Canberra this afternoon, Professor Kelly warned against a second wave of infections as restrictions around the country began to lift with no vaccine in sight.

"We're continuing to do well in Australia … in one sense we're victims of our success to an extent, because we've had so few people that have been diagnosed with COVID-19, and we are nowhere near that concept of herd immunity," Professor Kelly said.

"That would be one way of guarding against a second wave.

"[But] we're definitely not looking to do that in Australia, as some of the countries have either planned to do or have been forced to achieve very large caseloads."

Sweden and the UK are among the nations who have experimented with herd immunity, although the latter reverted to severe lockdown measures after a spike in cases, including Prime Minister Boris Johnson.

The controversial Swedish model initially made COVID-19 tests available only for hospital staff and at-risk groups, and encouraged life to continue almost as normal.

A herd immunity is not for Australia in the fight against COVID-19, Professor Kelly said. ( Reuters: Athit Perawongmetha )

Professor Kelly said a different strategy was needed to help Australia cautiously return to a less restricted society while preparing for a second wave.



"We've seen what [herd immunity] has done in other parts of the world, so we won't be going to that," he said.

"A second wave is always possible and that's why those three precedents have been set by the Prime Minister before we lift those social distancing and socialisation rules about case finding, keeping the cases low if possible.

"If cases occur, [it's about] finding them quickly, finding their contacts, quarantining them and decreasing the size of any outbreaks that we might have by having a very detailed and quick response.

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"If a second wave does occur, we'll deal with it quickly and we'll respond to it."



Although the second wave of the Spanish Flu pandemic in 1918 was worse than the first, Professor Kelly said he did not expect COVID-19 to follow the same pattern, with the advantage of medical advances and technology.

The high uptake of the COVIDSafe app is helping trace infections. As of Wednesday morning, the tracing app had seen more than 2.8 million downloads — more than 10 per cent of the population — since its introduction last Sunday.

"We are much better prepared than we might have been [for the Spanish Flu second wave]," Professor Kelly said.



"That ability to do the laboratory testing rapidly and accurately, to be able to find cases, find their contacts, is another reason to download the app. It will help us to fight a second wave.

"The longer we leave that second wave into the future, the more likely it is we'll have successful treatments."

Professor Kelly said it was up to states and territories to use their own judgment to ease restrictions as they saw fit, based on the rate of infections.

"That's not a mixed message. That is a changed message," he said.

"And we will, as we have always done, undertake to share those differences and share those announcements as soon as they come to be."

National Cabinet in expected to reassess nationwide lockdown guidelines in the week starting May 11.