Prime Minister Jacinda Ardern has received the first shot of the Pfizer Covid-19 vaccine as the country steps up efforts to inoculate its population, reports Reuters.

"I'm smiling under the mask," Ardern said as she sat down to receive the shot at a vaccination centre in Auckland, as the media watched on.

"For me, I never wanted to be amongst the first, for me we needed to get those front line workers but I also need to be a role model and this demonstrates that it's safe, that it's effective and that it's really important that everyone is vaccinated when they have their opportunity...," she said after receiving the vaccine shot.

"It's really true when they say it's actually pretty pain-free."

About 1 million doses of the Pfizer vaccine have so far been administered in New Zealand, a nation of five million people. The country's medical authorities are yet to approve the use of any other vaccine, including AstraZeneca.