Prime Minister Jacinda Ardern says a change in COVID-19 traffic light settings would not make a significant difference on surging case numbers.
She said the most important thing was for people to adhere to the current requirements - which meant wearing a mask and those over 50 getting a second booster.
COVID-19 cases continue to increase with 9000 cases reported yesterday and hospitalisations rising to 662, the highest mark since 5 April.
Ardern has seen many members of her own Cabinet fall ill with COVID-19 in recent weeks.
She told Morning Report that existing measures were being constantly reviewed and would be discussed again on a weekly COVID-19 call.
She acknowledged it was a very challenging time for the health system, including for hospitals, however, the basic measures were the country's most effective weapons in dealing with the virus.
"Mask use and vaccination continue to be the most effective things we can be doing ... they reman critical so it's a role we can all play to keep assisting with what is at the moment a not unexpected surge but a difficult one of B4 and B5 [Omicron sub-variants] in New Zealand."
COVID-19 case numbers are now similar to early April when the country was at a red setting.
Asked why the government was not therefore returning to the red setting, Ardern said one reason was that up to half of New Zealanders have had COVID-19.
The other reason was the highly transmissible nature of the B4 and B5 sub-variants.
The major difference for red settings was in stricter gathering limits and the experts' view was that this would not make a marked difference because older people were being most affected by COVID-19 at present, Ardern said.
Instead the critical factor was vaccination, she said, adding that over 50s should get their booster shots.
"It's our older population at the moment where we are seeing the increase in those case numbers. We really need to make sure they have their booster to make a difference to our health system."
The older population were the age-group most likely to need hospital care.
It was not new measures that would make difference - it was an uptake of current ones, stressing again that people needed to wear their masks and get a booster.
Masks would also help restrict the spread of flu.
"It's the combination of winter illnesses ... that are having a huge impact on our hospitals."
Health experts have advised 50 plus for the second booster and not many countries have followed Australia's example in offering the second booster shot to over-30s, Ardern said.
"This is not a decision for politicians, it's our experts."
Asked if the health system was now unable to cope, she said that was not the case. Healthcare staff were doing "an incredible job" and were also being hit hard by illness or having to look after unwell family members.
On Kiribati withdrawal from Suva forum
Kiribati's decision to leave the Pacific Islands Forum was not necessarily about wider security issues within the region, Ardern said.
The prime minister will be attending the Pacific Islands Forum which starts in Suva today.
She said she would prefer the country explained its reasons but it seemed to centre on representation issues around Micronesia.
"That's an issue that's not new. The forum has been working to resolve that, obviously they haven't resolved it to meet the expectation of Kiribati."
She did not believe the Kiribati issue could be linked to concerns over China's increasing influence in the Pacific.