There has been a significant jump in the number of new COVID-19 cases in New Zealand in the past couple of weeks, with authorities forecasting the current wave of Omicron infections could be worst than the first.

The hospital system is already struggling with increases in waiting times and surgeries having to be cancelled.

"There's no question the combination of a spike in COVID-19 cases and hospitalisations, the worst flu season in recent memory and corresponding staff absences are putting health workers and the whole health system under extreme pressure," Ayesha Verrall, Minister for COVID-19 Response, said in a statement.

New Zealand, which has a population of 5.1 million, recorded 11,382 new cases of COVID on Thursday, with a total of 68,737 currently infected with the virus. Of those, 765 are currently in hospital.

A one-time poster child for tackling the coronavirus, New Zealand's swift response to the pandemic and its geographic isolation kept the country largely COVID-19 free until the end of last year.

The government retired its zero-COVID policy earlier this year once the population was largely vaccinated and the virus has been allowed to spread.

Dr Verrall said, while COVID-zero was no longer a possibility, people still need to wear masks, get tested and isolate if they or anyone in their home tests positive to the virus.

The government is making free masks and tests more widely available, allowing pharmacies to sell COVID medicines and expanding the criteria for who is eligible for antiviral medication.

"Now's not the time to stop wearing masks. Evidence tells us wearing a mask halves your chance of being infected with COVID-19," Dr Verrall said.

"It also helps protect you against influenza and other winter illnesses. So if you don't wear a mask for yourself, please wear one for healthcare workers."

Australian Associated Press