NSW is pushing to increase the rate of booster vaccinations as the health minister calls for a national definition on what it means to be "fully vaccinated".

NSW recorded 7893 COVID-19 cases on Sunday and 28 deaths, including two people in their 40s.

There are currently 2321 coronavirus patients in the state's hospitals, 147 of them in intensive care.

Almost 43 per cent of primary school aged children have received one dose of a vaccine as they prepare for their second week back at school.

While 94 per cent of eligible NSW adults are double vaccinated against COVID, only 43.5 per cent have received a third dose.

Health Minister Brad Hazzard says the booster rate should be higher.

"The question in my mind is: If we have almost 95 per cent of people in NSW double dosed and we've got a little less than 45 per cent of people who have had the booster, what's happened to the other 50 per cent? Why aren't they out there getting their boosters?"

He says the state has "a lot of people" working on finding an answer to that question.

More booster shots have been administered in NSW than anywhere else in the country, but the state's rate should be higher because more people were eligible for boosters earlier.

About a million people are currently advised not to get a booster because they've had COVID-19 in the last four to six weeks.

Three months ago, NSW had a double dose vaccination rate of 89.3 per cent of people aged over 16, but eligibility for boosters was only expanded to 16 and 17-year-olds in NSW on Friday following advice of the Australian Technical Advisory Group on Immunisation (ATAGI).

Mr Hazzard says ATAGI should also provide advice nationally on whether a booster is required for people to be considered fully vaccinated.

Until then the state will be taking a more "encouraging" approach to promoting booster uptake and will hold off on mandating boosters for healthcare workers, Mr Hazzard says.

"One of the biggest factors is simply that people are not aware they can actually have the booster," Mr Hazzard says, prompting the expansion of the government's campaign to get people vaccinated.

The expanded ad campaign will be distributed in 19 different languages and also feature specific advertising for the Indigenous community.

Meanwhile, a survey of workers in the NSW disability sector has found that only 3.2 per cent reported having access to RATs for themselves and 3.2 per cent had tests for the people they support.

The Community and Public Service Union of NSW, which conducted the survey, has written to the NSW and Federal government warning of a COVID-19 crisis in the state's privatised disability sector with workers "forced to put themselves and those they care for at risk of infection".

The union's assistant secretary Troy Wright has called on the government to provide a surge workforce and retention pay.

"I am hearing stories from members of only finding out there are COVID-19 cases at the group home once they've arrived for a shift," Mr Wright said.

"We're hearing from members telling us their employer doesn't have enough PPE or any tests for them."

On Monday, elective surgery will return ahead of schedule in NSW, following a fall in hospitalisations.