As Australia grapples with the highly infectious Delta variant, experts say it is unlikely the trans-Tasman travel bubble will reopen.
New South Wales (NSW) recorded 344 new locally acquired Covid-19 cases and two more deaths on Wednesday.
Travel is set to resume next month following an eight-week hiatus, but Covid-19 modelling expert professor Shaun Hendy said that is nigh on impossible.
"We've seen them tighten restrictions over recent weeks and that tightening does not seem to be having the desired effect, so I think we do need to assume that the outbreak is going to be persistent for some time.
"It may grow to become considerably larger, that puts other states at risk in Australia, and so it probably means the end of the travel bubble," he said.
But there is some scope to resume travel with other parts of Australia, Hendy said.
"Some states such as Tasmania or maybe Western Australia, if over the longer run they're able to demonstrate that they're not picking up stray cases from New South Wales or other territories within Australia, then it may be that the government could look to open selective bubbles with those states."
Covid-19 Response Minister Chris Hipkins said the government has been closely watching what is happening across the Tasman and so far, has not ruled anything out.
When the travel does resume, it will look different, he said.
"Vaccination I think can play a bigger role here. It may be that there are vaccine requirements put in place as part of a reopening of safe travel zones. All of those things are things that we'll work our way through. Looking at what's happening in Australia, it's still some time away," he said.
The government warned it would quickly impose a level 4 lockdown if the Delta variant gets into the community here.
Professor Catherine Bennett is an epidemiologist at Melbourne's Deakin University said quarantine-free travel would be a long way off.
"You have to have such high levels of control with any single case, that will potentially mean that we cannot reopen the bubble.
"We're going to be longer term now. Still learning whether we will go back to zero in New South Wales or other parts of Australia in the short term, or whether we will just be trying to get this to manageable levels as we roll out the last bit of our vaccine programme," she said.
While the situation in Australia is terrible, there is a silver lining, Bennett said.
"Our vaccination rates have really accelerated. We're now hitting almost a quarter of a million doses being administered in a day. That's the good news in all of this. The sad thing is sometimes it takes these outbreaks to really motivate people to get vaccinated."
The city of Dubbo in NSW is the latest place in the state to go into lockdown after new Covid cases there.
Melbourne's lockdown has been extended for another week.