Sue and Graham Murphy's COVID-19 test results were negative.

"I almost broke down with relief," Mr Murphy wrote in a text message early Wednesday morning, after receiving the results.

To see the word "negative" on the paperwork, he wrote, was "just overwhelming". His wife, Mr Murphy wrote, was "a little more philosophical" about reading her report.

"She didn't care what the result was as long as we stayed together," he wrote. "She, of course, couldn't be happier with both our results."

The retired business couple from Largs had been on a cruise on the ship Greg Mortimer to Antarctica, when the impact of the pandemic reached even the bottom of the world.

Graham Murphy explained the cruise ship, operated by Aurora Expeditions, was called back to Argentina, where the tour had begun. But as ports closed, the Greg Mortimer ended up off the coast of Uruguay.

Testing by Uruguayan medical teams revealed coronavirus was on board the ship. Aurora Expeditions told passengers on Monday, local time, that 128 passengers and crew had tested positive for COVID-19. Eighty-nine had tested negative, with another 6 results pending.

At that stage, the Murphys were still waiting for their results.

"This is scary stuff," Graham Murphy wrote in a text message on Monday afternoon, his time (Uruguay is 13 hours behind Newcastle).

"A number of passengers and crew have been taken off the ship with C19-related illness."

Aurora Expeditions said six people had been taken ashore and were stable. Two hundred and seventeen remained on board the Greg Mortimer.

The Murphys have been in isolation in their eight-metre-by-four-metre cabin for more than a fortnight.

"Thankfully we have a small 4x1m veranda," Mr Murphy wrote. "We are fortunate to have fresh air and sit in the warm sun - when it shines.

"We are both in good spirits and health. We try to exercise as much as we can. One hundred and fifty laps of the room equal 1.2 kilometres."

The couple are hoping to hear later Tuesday, their time, when they and the other passengers are likely to return home.

Aurora Expeditions said in a statement it had chartered an aircraft that was being refitted as a "medical plane". The plan is for all Australian passengers to be on the same plane, which is likely to land in Melbourne.

In its statement, Aurora Expeditions said, "although we are still in the planning stage, it is likely we will separate the positive and negative passengers on the flight home into different cabin areas".

The company said the aircraft was likely to depart on Thursday or Friday, although Mr Murphy wrote there were indications that flight could be moved earlier.

In Maitland, the Murphys' son, Brad, was delighted when he heard about his parents' test results.

"Fantastic news," Brad Murphy said. "We're looking forward now to the next bit of getting them home."