This latest study: Researchers examined the Diamond Princess, a cruise ship which was quarantined off Yokohama in Japan last month, and found coronavirus RNA-genetic material-in the cabins of infected passengers up to 17 days after the ship was vacated and disinfected.
The number of coronavirus cases in WA has surged by 30, bringing the total to 205, including five from cruise ships.
The country is taking strict precautionary measures with arriving cruise ships after one liner, the Ruby Princess, disembarked in the country with minimal health screening.
However, the CDC says the findings did not show whether transmission of the virus was still possible via those contaminated surfaces, writing that "further study of fomite transmission of SARS-CoV-2 aboard cruise ships is warranted".
The seven confirmed cases are not in critical condition and remain on the ship.
The Western Australian premier, Mark McGowan, said on Wednesday that he would be "exercising the Rottnest option" for Australian citizens and residents aboard the Vasco da Gama, which was due to arrive in Fremantle on Friday.
"Its home port is actually Germany.This ship needs to leave immediately". "We want to make sure that those Australians are able to return".
All visitors to the island were told to leave this week, and McGowan said the government had "made arrangements for accommodation, catering and security" of people under quarantine.
"This ship and its passengers are a Commonwealth responsibility".
Mr McGowan said he thought Garden Island would be a suitable place to put sick passengers from the Artania who needed to go to shore for treatment.
It had been previously reported he was a passenger on board the Ruby Princess.
He also announced allowing pharmacists to write prescriptions for one month's worth of medication.
Rottnest Island off Perth will be a coronavirus quarantine zone for 800 Australians onboard the Vasco da Gama, as the number of cases from other cruise ships continue to rise.
Non-Australians on board - about 150 passengers and 550 crew members - will be made to remain on the ship until they can be flown home.
For the remaining worldwide passengers - all internationals will be kept on board and will only be removed and allowed off when safe and secure transport can be arranged to transfer them to their home country.
The ship's owner Cruise & Maritime Voyages told The Australian newspaper it had recorded no health concerns among its passengers or crew.
Mr Brazier said there were no reported health issues among those on board, who will have been at sea for 16 days by Monday.