The men remain on a bulk carrier which has been anchored nine nautical miles off Port Hedland since September 16.

Twenty Filipino nationals and the captain are onboard the Patricia Oldendorff.

Health Minister Roger Cook says the men are isolating from the rest of the crew, but both are comfortable and only one is symptomatic.

A rapid response team has arrived from Perth and other personnel including doctors and nurses are on their way.

No further positive tests have been recorded, but Mr Cook expects that to change.

"I think we have to be ready for the fact that there will be others who have contracted the disease," he said on Friday.

Authorities will look to evacuate the ship and have some crew members quarantine in Port Hedland, most likely in a local hotel.

About half of the men will remain onboard as a skeleton crew.

The rapid response team is being led by experienced doctor Tudor Codreanu, who also managed COVID-19 outbreaks onboard the Artania cruise liner and Al-Kuwait livestock ship earlier this year.

Mr Cook said he did not envisage crew members being flown to Perth unless they needed intensive care.

"We'll be keeping them in Port Hedland unless of course there's a clinical need to evacuate them to Perth," he said.

"Hedland Hospital is a new hospital, it's well-equipped and we've got some great staff there."

Security guards may also be flown to Port Hedland to oversee the crew's quarantine period.

Mr Cook confirmed an extra 40 Australian Defence Force personnel would arrive in Perth next week to help manage the increased intake of returned overseas travellers.

No new cases were recorded on Friday but nine remain active.

Australian Associated Press