First discovered last week, the outbreak has grown to 107 cases. But health authorities say they've found links among most of those cases, giving them hope they can quash the outbreak. Authorities said they've tested about 3% of the nation's entire population over the past six days.
Prime Minister Jacinda Ardern said the lockdown will continue until at least the end of the month in Auckland, where most of the cases have been found.
“We do need more information. We need more certainty. We don’t want to take any risks with delta,” Ardern said. "If the world has taught us anything, it is to be cautious with this variant of COVID-19.”
Ardern said modeling suggested the outbreak should peak in a few days' time, and then decline.
One of the reasons lockdowns are considered essential in New Zealand in that inoculation rates remain low, with only about 20% of people fully vaccinated. The strict lockdown means most people must remain at home, leaving only to buy groceries or medicine, or to exercise.
Ardern also announced that the government has decided to suspend regular Parliament sessions for a week, a move that drew criticism from opposition lawmakers.
“At a time when New Zealanders have the harshest lockdown in the world and have lost our freedoms because of the government’s failure to vaccinate and secure the border, this move by Jacinda Ardern is unfathomable," said Judith Collins, the leader of the opposition.
Australian Prime Minister Scott Morrison said lockdowns are were “not a sustainable way to live in this country.” He said states must open their borders once vaccination rates reach 80% of the population aged 16 years and older.
His remarks came as an outbreak in Sydney grew by more than 800 cases, near record levels. Health authorities said an outbreak centered in Melbourne also grew by 71 cases and another in the capital, Canberra, grew by 16 cases. All three cities remained in lockdown.
But in Western Australia, where there are no community infections, Premier Mark McGowan said his government wouldn't reopen at the 80% vaccination level if it meant reintroducing the virus.
About 24% of Australians are fully vaccinated.
McGuirk reported from Canberra, Australia.