An epidemiologist is warning New Zealanders not to be complacent if we move to alert level 2. 

Hospitality, retail and domestic air travel will all be allowed under Level 2, providing we all keep our distance.

The Prime Minister has outlined what a move to the next level will mean, with the measures possibly coming into effect next week.

But Jacinda Ardern's given a strong indication that change might not all come at once and will follow Health Ministry advice.

Ardern says if the advice is to move out of level 3 in phases because doing it all at once would have too many risks. She says she'd rather take that advice than stay at level 3 longer than we need to.

University of Otago epidemiologist Michael Baker told Heather du Plessis-Allan that a phased approach is the right move. 

"The real problem is complacency that we think maybe we've got the virus under control, but unfortunately there will almost certainly still be virus circulating in New Zealand.

"Under level 3 and 4, we have suppressed the transmission. So we could just be in a slightly deluded place at the moment thinking it's all gone and acting accordingly."