Prime Minister Jacinda Ardern has asked New Zealanders to get vaccinated as soon as possible, as it is the only way to beat the spread of coronavirus and see curbs lifted in the biggest city of Auckland.

Tuesday's 15 new infections in New Zealand were a drop from Monday's figure of 33, but about 1.7 million people will stay in lockdown in Auckland until next week, as the government battles to hold down a cluster of the highly infectious Delta variant.

“The vaccine is the best tool we have in our toolbox and our ticket to greater freedom,” Ardern told a news conference. “The more people who are vaccinated, the fewer restrictions you have to have.”

Auckland's lockdown has shut schools, offices and public places, with people allowed to leave home only for exercise or to buy essential items, according to Reuters.