“Our case has originated in Australia,” Ardern told a press conference. The trans-Tasman free quarantine travel started in April and was suspended last month due to the outbreak in Australia’s several states.

One of the new cases announced earlier on Wednesday is a 20-year-old workmate of the first case announced on Tuesday who was a 58-year-old man in Auckland’s North Shore. Another three are roommates of this workmate, with two others being friends with the four cases, said Director General of Health Ashley Bloomfield.

One of the three roommates is the fully vaccinated 21-year-old nurse who works at the Auckland City Hospital and had been working in recent days, Bloomfield said, adding that the hospital has taken immediate actions to shut down any potential spread, including stopping unnecessary movements between wards and testing all staff and patients on the ward.

Ardern said the nationwide lockdown was appropriate.

“Our whole ambition here is: do it once, do it right. Short and sharp is better than light and long and I think we all agree,” she told New Zealand local media during a morning interview.

On mask use, Ardern said from 11:59 p.m. Wednesday it will be mandatory for people aged 12-plus to wear a mask when visiting essential services such as supermarkets, pharmacies and service stations, and staff must also wear masks.

Masks must also now be worn at bus terminals and in taxis, she said.