People stand on a pier outside the Ruby Princess cruise ship and wait to be picked up in San Francisco, Jan 6, 2021. (PHOTO/AP)

SYDNEY - Carnival Corp's Australian unit has been ordered to pay the medical expenses of a woman who contracted COVID-19, with a judge ruling that the cruise ship operator misled passengers about safety risks in a landmark class action ruling.

The decision from Australia's Federal Court is the first class action win against a cruise ship operator in the world, according to Shine Lawyers, who represent about 1,000 Australian plaintiffs in the suit.

Justice Angus Stewart found Carnival Australia misled passengers about the measures it had in place to keep passengers from contracting the virus and that it should have cancelled the March 2020 return voyage from Sydney to New Zealand.

The Ruby Princess was for a time Australia’s biggest single source of COVID infection after 2,651 passengers, many feeling unwell, were allowed to leave the ship helping spread the virus across the country and internationally

Lead plaintiff Susan Karpik was awarded A$4,423.48 ($2,826) for out-of-pocket medical expenses but no damages.

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Carnival Australia said in a statement it was considering the judgment in detail. Legal filings show the operator denied it knew before the voyage that the risk of contracting COVID was higher on a cruise ship than in the community.

Karpik, who was along with her husband Henry had been a passenger on Ruby Princess, had claimed more than A$360,000, in part due to the psychological distress of her husband's two-month hospitalization with the virus, during which he was at one point given only days to live.

Carnival is likely to face larger damages when the court considers the claims of the remaining parties including Henry Karpik's, according to Vicky Antzoulatos, joint head of class actions at Shine Lawyers.

"The case in point is Mrs Karpik's husband, who was in intensive care for weeks and suffered serious injuries," she told Reuters.

"Although the judge found Mrs Karpik didn’t meet the threshold for pain and suffering damages, other passengers will."

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The number of plaintiffs could also grow should Australia's High Court rule that some 700 US passengers can be included in the class action.

The case is a rare win against a cruise ship operator, Antzoulatos said, saying the industry often operates in jurisdictions where it is difficult to sue, especially where class action suits are concerned.

The Ruby Princess was for a time Australia’s biggest single source of COVID infection after 2,651 passengers, many feeling unwell, were allowed to leave the ship helping spread the virus across the country and internationally.

Ultimately around 900 cases and 28 deaths would be linked to the outbreak.

A 2020 public inquiry into the outbreak concluded New South Wales state health officials made "inexcusable" mistakes when they allowed passengers to disembark.