Nine people remain on the Patricia Oldendorff as essential crew, and seven of them have tested positive.

There are also a dozen crew members in quarantine at the fenced-off Hedland Hotel, 10 of whom have tested positive.

No new cases were reported on Tuesday, leaving the state with 22 active cases, including five unrelated to the Patricia Oldendorff.

"The crew who have returned positive results are not seriously unwell and are in good spirits," Health Minister Roger Cook said.

"Safety of the maritime workers, emergency services and transport staff, hotel staff and the local community continues to be our number one priority."

The ship, carrying 20 Filipino nationals and the captain, is anchored eight nautical miles off WA's northwest coast.

It arrived from Manila on September 16.

Australian Defence Force personnel will arrive on Thursday to help local police and security guards oversee the hotel quarantine.

Nine crew are needed to maintain the ship while it is anchored, and maritime laws require 13 people to be aboard when it departs for international waters.

"My preference is that we take the crew off. We can care for them better there, we can do the deep clean of the vessel and we can get it under sail," Mr Cook said.

"The limitation we have is we've only identified about five crew that we can actually put back onto that ship."

Once some of the hotel occupants have exceeded their incubation period and are no longer infectious, they could form part of a "clean" replacement crew.

"We're anticipating that this scenario will resolve itself within a fortnight," Mr Cook said.

WA authorities are working to ensure the outbreak does not affect trade at Port Hedland, a major thoroughfare for commodity exports.

"This is literally the engine room of the nation's economy," he said.

"It's important we keep this port open and it's important we're confident about the arrangements in place for foreign crews, so this is going to be the subject of a significant and deep inquiry."

Mr Cook also dismissed concerns about Hedland Hospital's facilities, saying it had negative-pressure rooms and a high-dependency unit suitable for COVID-19 patients.

"Hedland Hospital completed an outbreak response on this very scenario only a month ago and is fully compliant with our needs," he said.

Mr Cook will travel to Port Hedland on Wednesday and will attend a community forum for concerned residents.

The government meanwhile announced eased restrictions for people arriving from Victoria and NSW.

From next Monday, Victorian arrivals - who remain subject to tight exemption criteria - will be allowed to self-isolate rather than entering hotel quarantine at their own expense.

People in NSW will no longer be subject to tighter exemption criteria than those from other states.

Australian Associated Press