There's a push to prioritise younger people for vaccinations as NSW prepares to roll out doses to supermarket workers to curb the spread of coronavirus.

A leading epidemiologist wants under-40s prioritised for vaccinations to curb rolling coronavirus outbreaks, lockdowns and border closures.

Mary-Louise McLaws is also calling for more Pfizer doses to be funnelled into NSW and Victoria.

The two states represent 58 per cent of all infections across Australia.

"If we actually go to hotspots, such as Victoria and NSW, and dampen down that risk by focusing on the 20 to 39 year olds who have had most infection, then the rest of the states and territories around Australia won't have to suffer," Professor McLaws said.

"I know it feels unfair. But from an epidemiological perspective, you go where you're going to get most of your results."

Frontline supermarket and warehouse workers in Sydney hotspot areas will be given priority access to Pfizer doses as the city's lockdown continues.

Pfizer gives under-40s the greatest protection from symptomatic infection.

Professor McLaws wants to see real-time testing of people without symptoms at essential workplaces.

"You need to catch them before they enter the workplace, go onto the factory floor, stacking shelves for us, with our food, getting into trucks, instead of just being tested every three days," she said.

"And then you might be able to break that cycle."

Former federal health department secretary Jane Halton supported priority sites for workers most at risk of contracting the disease.

"Get those people vaccinated and get them vaccinated now," she said.

NSW is consistently reporting more than 100 new infections a day and Sydney's lockdown will almost certainly extend beyond Friday.

But Victoria and South Australia are set to exit their lockdowns after bringing Delta outbreaks under control.

The federal government has resisted a push to or expand disaster relief payments to people on welfare or bring back its original JobKeeper scheme that linked workers to employers.

Nationals deputy leader David Littleproud said the current payments were faster and more flexible.

"It would take too long to get money into people's pockets so we've shown some agility in putting this COVID payment that will go to many people who would miss out if JobKeeper was put in place," he said.

"It's not just the federal government that has to work through this.

"It's important the states open their minds to that and not just go to the old ATM of the federal government all the time."