Cabinet ministers will discuss a transtasman travel bubble with Australia on Monday with a view to mid to late April as a potential start date, the Herald understands.

This follows comments by Covid-19 Response Minister Chris Hipkins, who yesterday indicated that a bubble would be at least three weeks away because airports and airlines would need that time to set up the necessary systems.

Meanwhile Christchurch Airport says it is ready for a two-way transtasman bubble, and it has been ready since last October.

It comes amid a slow start to the roll-out of the Pfizer vaccination; a graph released yesterday indicated that about 30,000 doses a week should be administered at the moment, but only about 9000 were delivered in the last week.

The graph is only an approximation, but the Herald understands the roll-out is already slightly behind schedule and the Government is keeping a close watch to ensure there isn't any further slippage.

Hipkins said yesterday the biggest challenge in the roll-out will be in the last quarter of the year, when about 250,000 doses per week - or 35,000 doses per day - are anticipated to keep up with demand.

The National Party has been pushing the Government on opening the travel bubble now, and a petition it started this week has now collected about 37,000 signatures.

Only one visitor from Australia so far this year tested positive for Covid-19 while in managed isolation, and health experts have described a transtasman bubble as very low risk.

A bubble is also highly anticipated by the struggling tourism industry hoping an influx of Australian visitors will ease the loss of foreign tourists.

National MP Chris Bishop grilled Hipkins about the earliest possible start date for the bubble yesterday, and he replied that airlines and airports would need at least three weeks' time to put practices in place so a bubble could operate safely.

The Government is looking at a unilateral decision-making framework for the bubble, rather than a joint framework with Australia, and Hipkins said many issues remain unresolved.

Those include when the bubble should be suspended, what happens to stranded Kiwis if it is suspended, the testing requirements in both countries, the exit visa requirements for Australians coming here, and the contact tracing compatibility of both countries' systems.

Including other countries in the bubble is also a consideration, and people are already allowed to travel to New Zealand from the Cook Islands and Niue without having to quarantine.

Cook Islands Prime Minister Mark Brown is due to visit New Zealand next week, the first leader to be hosted in New Zealand in more than a year.

Yesterday there are no new cases of Covid-19 in the community, and there were three in MIQ for arrivals from Iran, Singapore and the USA.

There were 6047 tests processed yesterday, and the seven-day rolling average of new cases detected at the border is three.