Deputy Nationals leader David Littleproud has warned caravans could become the cruise ships of the outback by spreading the deadly coronavirus.

An influx of caravans into regional Australia has sparked grave concerns in country communities as the national coronavirus death toll rises to 20.

Mayors are pleading with grey nomads and other holiday-makers to stay home and relieve pressure on towns under pressure during the pandemic.

A 95-year-old woman has died in Sydney, taking the Australia-wide number of deaths to 20, including nine in NSW.

Deputy Nationals leader David Littleproud, whose sprawling electorate covers 729,000 square kilometres of regional Queensland, said people must not seek refuge in country towns.

"Otherwise, these caravans could turn into the cruise ships of the outback," he told ABC Radio National on Wednesday.

Mr Littleproud said despairing mayors were reporting supermarket shelves being stripped by city-dwellers looking to escape urban centres as the virus spreads.

"You don't have to be Agatha Christie in one of these towns to know why they're there," he said.

Infection rates appear to be slowing, with an average of nine per cent increase in cases over the past three days compared to 25-to-30 per cent a week ago.

Deputy chief medical officer Nick Coatsworth said officials were treating the figures with caution.

"It's clear that we've landed a punch on COVID-19, but it's by no means on the canvas," he told Sky News.

"This is a promising sign but we need to be very cautious and it is no time to take out foot off the accelerator."

Dr Coatsworth said health authorities had been working diligently behind the scenes to boost Australia's intensive care capacity since horrific scenes in China and Italy emerged.

There are about 60 coronavirus patients in intensive care, with scope for 4400 beds to be made available immediately.

The national target is 7200 beds.

"I'm comfortable at the moment with our capacity," Dr Coatsworth said.

Strict physical distancing measures are being enforced in NSW, with police patrolling public places to make sure people are following the rules.

Harsh fines and jail time could be applied if people continue to break public health orders.

Dr Coatsworth said while some may criticise police for being heavy handed, the strict tactics were about protecting society.

"We're in a pandemic. This absolutely has to be enforcement," he said.

Mr Littleproud backed tough penalties for people ignoring the order to stay at home unless they are exercising, collecting essential supplies, working or studying.

"Those that want to flout the law, we should throw the book at them," he said.

The federal government has struck a deal with 657 private hospitals to provide an extra 34,000 beds and more than 100,000 staff.

Around 300,000 businesses have registered for $1500 fortnightly wage subsidies for each worker as part of a $130 billion program.

More than 4500 cases of coronavirus have so far been detected across Australia.

Two border force officers - one from NSW and one from Queensland - are among those who have tested positive.