New Zealand's prime minister rolled up her sleeve on Wednesday afternoon at a clinic in Hamilton.

"It was fine. Really, really easy," she said.

Enjoying an orange lollipop for her troubles, Ms Ardern appealed to Kiwis to follow suit and get vaccinated.

"The Delta variant is spreading around the world. We are not out of the woods yet. To be effective, we need everyone," she said.

"It's an act of kindness on behalf of the rest of the country."

The spread of the more contagious Delta is a key reason why NZ has abandoned the trans-Tasman bubble, shutting off quarantine-free travel until mid-September.

After notching 150 days without community transmission of the deadly virus, NZ is in a delicate phase of the pandemic.

Kiwi leaders fear an outbreak now, more than ever, given the enhanced threat of Delta against a largely unvaccinated population.

NZ ranks 125th in the world for vaccines administered per capita; running well behind the global average.

Just over 21 per cent of New Zealanders have had at least one jab. Ms Ardern was roughly the 700,000th Kiwi to receive their second.

NZ is only now moving to vaccinate the general population, after prioritising at-risk populations as well as border and health workers.

The long-promised scaling up has arrived.

For the first time, NZ administered 200,000 doses last week, and this weekend the first mass vaccination event will be held in South Auckland.

As of Wednesday, anyone aged over 60 can also book their vaccination.

Opposition party National has lashed the government's "excruciatingly slow and chaotic vaccine rollout", saying Ms Ardern should follow Australian Prime Minister Scott Morrison's lead.

"If Australia's vaccine rollout has been so bad that their PM had to apologise, ours should do the same, given the Aussies are actually ahead of us," Opposition Leader Judith Collins said.

Australian Associated Press