The first people to get the Covid-19 vaccine tomorrow will be some of the 100 vaccinators who will then immunise those working at the border.
As part of the nationwide programme, vaccinations will begin to be rolled out to 12,000 border workers and their families from Saturday.
There are currently 60,000 doses of the Pfizer vaccine in the country, enough for 30,000 people.
Minister for the Covid-19 Response Chris Hipkins said trial runs took place in Auckland and Christchurch yesterday and Wellington is also holding a rehearsal this week.
Officials have been working on the system for months and the dry run gave them a chance to spot any gaps and put in place any additional support that might be needed, Hipkins said.
Because it was the biggest vaccine rollout in the country he is expecting some challenges in logistics.
"But the systems we have set up for phase one for our border workers are robust and flexible and the more that we do to test them to ensure they are robust, the more that we'll be prepared to scale up the system when we reach that point [vaccinating the bulk of the population]," Hipkins said.
Scenarios covered yesterday included a spilt vial, a failure in technology, handling the arrival of the thermal protection boxes that contain the vaccine and the delivery people handing over the vaccine supplies.
Both the Defence Force and Fonterra had been involved in the logistics, he said.
As well as the 100 vaccinators involved in vaccinating the border workers, another 300 vaccinators are being trained for the broader rollout later in the year, Hipkins said.
A GP who has helped design the Covid vaccine rollout said he was confident it will be effective and safe.
Dr Joe Bourne said the practice run included patient role plays.
"We know that there's so much publicity around the delivery of this programme and people will talk to each other about what the experience was like.
"So the team felt that having somebody there and rehearsing the conversations they will have in certain scenarios was really helpful for them."