NSW is heading for a resurgence of COVID-19 cases driven by Omicron subvariants, as the state's health minister labels anyone who hasn't received three vaccine doses as "crazy".

Chief Health Officer Kerry Chant expects the state's third wave to peak in late July and early August at levels similar to January, when the virus was raging.

Health Minister Brad Hazzard is urging people to get their vaccine booster shot as statistics show deaths are disproportionately among those who aren't triple-vaccinated.

"If you've had two (doses), for example, or one and you haven't had your full three - to put it bluntly, you're crazy," Mr Hazzard told reporters on Tuesday.

"That is what's going to make a difference to stopping, or at least reducing the chances of you ending up in hospital or possibly dying."

NSW has recorded 1232 COVID-19 related deaths this year, with 56 per cent occurring among people who hadn't received three vaccine doses.

Some people missed their third jab because they were busy or thought the pandemic was over, Mr Hazzard said.

"On both of those counts, they're wrong," he said.

The surge in cases is being driven by two immunity-evading Omicron subvariants, BA.4 and BA.5, and health experts believe the number of cases and deaths will continue to grow.

Mr Hazzard said the availability of antiviral treatments was limited to the elderly and people with co-morbidities but work was being done to expand the criteria.

"(Antivirals) definitely make a difference for the majority of people who actually get the COVID virus," he said.

Dr Chant said receiving two vaccine doses no longer meant a person should be considered fully vaccinated against COVID-19.

"The virus has changed ... we need three or in some cases four doses to provide the best protection against getting very sick," she said.

Dr Chant said she was concerned because the coronavirus wave was taking place while the community also dealt with surges of the flu and other respiratory viruses.

She called on people to keep up to date with their vaccinations, wear masks indoors and stay at home if they had cold or flu symptoms.

Some 68.1 per cent of the eligible population has had three or more vaccine doses.

AMA NSW president Michael Bonning said hospitals were already experiencing high levels of demand from COVID-19, flu and other respiratory illnesses.

He also urged NSW residents to wear masks indoors as a simple way to curb the spread of viruses.

"If we want to preserve the business as usual this time around, we need to continue following orders and respecting the health and wellbeing of others," Dr Bonning said.

"Mask-wearing isn't just about protecting yourself but protecting others from your own respiratory droplets."

NSW recorded 10,504 COVID-19 cases and 14 deaths in the latest 24-hour reporting period.