The Auckland area is almost 23,000 doses of the Pfizer vaccine behind schedule, but experts say it's too hard to say at this stage if the rollout is in trouble.
The national vaccine rollout is currently 9 per cent ahead of schedule, but Auckland Metro - which includes the three DHBs in the area and makes up more than a third of total doses administered - was one of four regions that are lagging.
Northland, which was at only 62 per cent of its target in late April, is now only 165 doses behind its schedule, while Wairarapa is 395 doses behind and Hawke's Bay is 606 doses behind.
Auckland Metro, at 91 per cent of its target, is 22,769 doses behind schedule.
Auckland University vaccinologist Dr Helen Petousis-Harris said it was worth keeping a close eye on Auckland vaccination numbers.
"These are just [DHB] estimates so it's very difficult to know," she said when asked if it meant the rollout was in trouble.
"You don't want it dropping back. We really need to advance this."
Immunisation Advisory Centre director Dr Nikki Turner said it was "not likely to mean anything at this point".
"There's loads of planning going on so numbers will vary a bit."
Director-general of health Ashley Bloomfield said he wasn't worried.
"I know they are continuing to roll out, for example, additional general practice hubs. They already have about a dozen in place, and there are further ones coming online."
He said the vaccination rollout could slow down or even pause if the Pfizer shipments for July didn't arrive - but he was confident they would.
"We are intending to use the vaccines we have got in anticipation that more will come. If there is a situation where we need to slow things down for a week or two, we will do that," Bloomfield said.
"However we are at this point confident that Pfizer will deliver, and there's no reason to believe they won't."
There are currently about 260,000 doses to be used in the country, with about 50,000 a week arriving for the rest of the month.
That means that, based on the current rate of vaccination, stocks will run dry in July if July shipments are a no-show.
Bloomfield said he is expecting to hear from Pfizer about July shipments in the next few days.
There was no plan B if they didn't arrive, he said.
Medsafe is yet to approve any other vaccines, and while Janssen is the closest, Bloomfield said he didn't know the earliest date they could arrive - if approved.
"They can't give us dates until it's been approved."
There are more than 235,000 Kiwis who have had two doses of the Pfizer vaccine.
Bloomfield said the borders wouldn't snap open once the rollout finished, even it was completed on schedule by the end of the year.
"It is quite clear that this pandemic is probably not even halfway through. We might be at the end of the beginning, but we can see new variants emerging all the time, countries previously keeping the virus out now being challenged by that, outbreaks emerging in countries like India recently that are extremely extensive.
"Vaccinating the population gives us more options, and the discussions right across Government and with the business community are about how we exercise those options that maintain our current protections of New Zealanders."
Associate Health Minister Ayesha Verrall added: "To that end, it won't feel like flicking a switch at the conclusion of the vaccination programme."
Verrall said the Government will decide and announce tomorrow whether to extend the pause in the travel bubble with Victoria.
Earlier today Victoria's lockdown was extended for parts of the state. It was originally set to end at 11.59pm on June 3, but now will be extended for another seven days.
Verrall reminded Kiwis stuck in Melbourne that the Government had a "flyer beware" warning.
"People had to be ready for community transmission and lockdown where they are, and that has happened."
There were no current arrangements for bringing people back but that would be part of today's reassessment, she said.
They would also be discussing a form of risk assessment for any New Zealanders who needed to return.
Bloomfield said the Ministry of Health was looking at options for Kiwis travelling from Melbourne even if the lockdown continued, which could include a pre-departure test, a test on arrival, and a stay in MIQ.