The doctor on a cruise ship stricken by COVID-19 and gastro has declared the outbreak over, but concern remains over an uptick in cases in the broader community.

The 'Grand Princess' cruise ship docked in Adelaide on Monday morning following an 18-day round trip to Queensland and back.

Passengers are disembarking the ship, which has capacity for 2600 guest and 1150 crew members, and South Australian premier Peter Malinauskas said those needing urgent care would be transported to hospital facilities in a way that was safe.

"It's been something we've been monitoring pretty closely over the last 48 hours," Mr Malinauskas told Nine's Today show on Monday.

"The good news is reports that we've got from the cruise operators that the number of cases presenting has actually dramatically decreased over the course of the last couple of days."

Mr Malinauskas said only 0.6 per cent of passengers had gastro and the COVID rate on board the vessel was relatively in line with the rest of the community.

Passengers who had tested positive were not allowed to take part in shore excursions and had to remain on the boat, in line with commonwealth health protocols, the premier said.

Cruise operator Princess Cruises said the number of guests with symptoms was in the single digits.

On a previous voyage, a round trip from Melbourne to Brisbane, "a number of people" reported acute gastro and respiratory illness symptoms to the ship's medical centre.

"While most guests were unaffected by illness on that voyage, we proactively launched a comprehensive disinfection program, developed in coordination with international health authorities to prevent further spread," a spokesperson for Princess Cruises told AAP.

"In an abundance of caution, there will be another disinfection program carried out on board the ship in Adelaide today before Grand Princess returns to Melbourne on Wednesday."

In a statement, SA Health confirmed the ship docked in Melbourne on Saturday to undergo a clean, and all passengers disembarked while that was undertaken.

"We have been in contact with the ship's doctor this morning," the statement said.

"SA Health has been informed that the outbreaks have been declared over and the few remaining cases are consistent with numbers you would expect on any cruise."

The Australian Medical Association said COVID cases in South Australia have increased 47 per cent in the past week and 150 per cent in two weeks.

While the AMA was concerned about the nationwide spike, SA branch president John Williams said the community has the tools to deal with a rise in infection.

"What has been said is that possibly there will be a peak around Christmas time," he told ABC Radio.

"We certainly hope that isn't the case but it is something we have to be aware of in the community."

Dr Williams urged people to keep good hand hygiene and wear a mask if they show symptoms. He recommended vulnerable Australians, including the immunocompromised and over 65s, consider a vaccine top-up if they haven't had one in the last six months.

"As far as the rest of the community goes, there's no need to be afraid," he said.

"We've rehearsed this. We can be kind to ourselves and the people around us and take appropriate precautions."