A German grandfather who contracted coronavirus whilst on-board a cruise ship has celebrated a life milestone in hospital as he recovers.

Johann Steinborn was one of 81 passengers and crew who contracted the virus, despite having no symptoms beforehand.

Steinborn’s health quickly took a turn for the worse and he was evacuated and put on an incubator.

"I only remember I was brought here from the ship and had to wait in a special room, then nothing – cut off, complete black," he told 9News.

"I don't know what happened to me."

His wife was flown home to Germany as she was healthy, but Johann remained behind as he has spent the last three weeks in a coma.

"Four weeks ago, I couldn't stand," he said.

"After lying in a coma, (my) muscles had disappeared."

After recovering from coronavirus, he is celebrating his 80th birthday and despite being away from his family, the nurses who are caring for him surprised him with photos from home and his favourite traditional treats.

Steinborn said that there were no signs of sickness during his time on the Artania until it docked in Sydney, where it took on an extra 100 passengers.

When the boat had reached Perth, the virus had rapidly spread, with almost 15 percent of Western Australia’s cases being linked to the cruise ship.

Three people died from the virus on-board.