Kiwis heading to Australia when a quarantine-free travel bubble is in place will be on their own if a Covid-19 outbreak leaves them stranded, the Government is warning.

"Ultimately, New Zealanders who travel to Australia will be assuming a degree of risk of being stranded," Covid-19 Response Minister Chris Hipkins told reporters today.

"One of the things people will need to be aware of when they travel to Australia is if they are stranded, they will have to be able to support themselves."

The Herald understands Cabinet will consider a starting date - possibly in April - for the bubble on Monday, but Hipkins would not be drawn on the earliest date a bubble could open.

"As soon as I'm in a position to set down some firmer dates, I will do that," Hipkins said.

New Zealand and Australia will each have their own rules about when to close the bubble, following the abandoning of a joint framework last month.

"The key thing is understanding the response framework of each country," Hipkins said.

Government compensation for stranded travellers was off the table, he said, nor was it likely that insurance would cover Covid-related travel disruption.

National Party Covid-19 response spokesman Chris Bishop said it was good to hear that the bubble might open next month.

"There's a human cost of not having the bubble - families split and people missing significant births and deaths and marriages, things like that."

Hipkins said airlines and airports have indicated they are ready to put systems in place to keep "green zone" travellers and aircrew separate from others, but they'd still need up to three weeks to implement them.

Passengers transiting through Australia would need to be come in on different flights as "green zone" travellers.

Cabinet also needed to consider how to allocate the 30 to 40 per cent of MIQ spaces that would open up if a bubble was up and running.

Not all of those rooms will be made available, Hipkins said, given the higher risk of travellers having Covid-19 from countries other than Australia.

"I wouldn't guarantee that 30 to 40 per cent would automatically be available to travellers from other areas," Hipkins said.

Some MIQ rooms would also need to be kept free in case a Covid-infected person was found to be on a "green" flight, which would see everyone on the flight placed in MIQ.

Christchurch airport has already made changes to allow for separate processing of "red" and "green" flights based on schedule separation and cleaning.

"We have also begun construction to physically split the international arrivals area into two distinct pathways to allow simultaneous operations," chief aeronautical and commercial officer Justin Watson said.

The airport's frontline staff have been vaccinated and are looking forward to safely welcoming international travellers again, he added.

Auckland Airport has also taken steps towards separating passengers according to their origin and Covid risk.

Meanwhile Hipkins said the Pfizer vaccination roll-out was not behind schedule despite a Ministry of Health graph indicating that there should be 4000 doses being administered per day - about twice what is currently happening.

He said he was keeping a close eye on the daily numbers, and he expected it to be 3000 to 4000 doses a day next week, and 6000 to 7000 a day the following week.