The entire country will be at alert level 4 – the highest level of lockdown – for at least three days from midnight, and the regions of Auckland and Coromandel for four to seven days.

New Zealand has not had a level 4 lockdown in more than a year, and the case is believed to be the first Delta in-community transmission.

The prime minister, Jacinda Ardern, said: “Delta has been called a gamechanger, and it is. It means we need to again go hard and early to stop the spread. We have seen what can happen elsewhere if we fail to get on top of it. We only get one chance.”

Under level 4, all New Zealanders are asked to shelter in place in a “bubble” that only includes their immediate household or dependents. They can only leave the house to buy food or medical supplies, to access medical care or for socially distanced exercise.