The only way Australia can avoid ‘yo-yoing’ in and out of lockdown is to drive coronavirus cases down to zero, a leading think tank has warned.

The Grattan Institute modelled three scenarios – unmitigated spread, low-level community transmission and complete eradication, and found the only way to avoid multiple lockdowns was to get to zero cases.

Improving the speed of contact tracing, implementing smarter restrictions on low-risk, high-reward activities, and setting clear thresholds for when constraints can be eased, the government would avoid the enormous economic and social costs of multiple lockdowns.

But an international quarantine will have to remain for the rest of the pandemic, even if Australia got its case numbers to zero, the report said.

“To maintain zero cases there must be effective quarantining of all international arrivals. States must ramp up testing. Contact tracing must be quicker and more efficient, so any cases that sneak through can be jumped on,” the Go for zero: How Australia can get to zero COVID-19 cases report reads.

Scott Morrison unveiled a road map for Australia’s coronavirus recovery in May.

A policy of dampening coronavirus flare-ups will not only drain the spirit of Australians and have a worsening effect on mental health and domestic violence rates, but also negatively impact the economy.

“What we’re saying, it is risky to have a strategy that allows it to circulate in the community,” lead author Dr Stephen Duckett told The New Daily.

“It’s almost inevitable you’ll have an outbreak in the future and we’ll go back into lockdown. That means community and business uncertainty continues,” Dr Duckett said.

“Going for zero now is actually a better strategy for health and economic reasons, rather than letting it bubble along.”

The report argues for Victoria to maintain restrictions for longer in order to ‘‘significantly reduce its chance of outbreaks in the future’’.

Dr Duckett said without a goal of zero cases, outbreaks would move between the states.

“The outbreak in Victoria led to outbreaks in NSW. You’ve got to be in it together,” he said.

Going for zero cases now would save the nation more pain later, the report said.

“If we’re in a yo-yo economy and yo-yo lockdown, people will get tired of it. They’ll say ‘Why don’t you fix it once and for all?’.”

For the road map to work, the federal and state governments need to be open about when restrictions will be phased out, he said.

The report suggests when there are fewer than 20 new daily cases for five days straight, states could allow gatherings outdoors of 10 people.

Up to five people would be allowed to gather indoors.

When there are fewer than five new daily cases for five days, this would go to public gatherings of 30 people and indoor gatherings of 20.

Importantly, the government needed to communicate what it was doing to the public, Dr Duckett said.

“The government needs to be clear about what we’re doing. National cabinet in July said zero cases. It’s all good to say that’s our aim, but we need to do something to get there.

“The government needs to tell people what the future is. They need to be clear when they can lift restrictions and what they can lift.”