The world’s largest cruise operator, Carnival, has been ordered to pay the medical bills of a passenger who caught Covid-19 on board one of its liners.

An Australian judge ruled the company misled passengers about safety risks, and should have cancelled a voyage by the Ruby Princess in March 2020 before it departed.

Some 900 Covid cases and 28 deaths were linked to an outbreak onboard.

The landmark ruling could open the door to hundreds of others claiming damages.

The case’s lead claimant Susan Karpik, a retired nurse, was travelling with her husband Henry on the Ruby Princess as it sailed from Sydney to New Zealand in March 2020, right at the start of the pandemic.

Some 2,671 passengers and 1,146 crew members were on board.

Mr Karpik, a retired police officer, fell ill with the virus and was hospitalised for two months, during which time he was put into an induced coma and at one point given days to live.

The judge ruled Carnival’s Australian division was found to have been “negligent and in breach of their duty of care”, and ruled Ms Karpiks should be awarded A$4,423.48 ($2,826) plus interest for out-of-pocket medical expenses.

This is a fraction of the A$360,000 she sued for, but the ruling opens the door to 1,000 other passengers who travelled on the same voyage to make claims.

Judge Agnus Stewart ruled that Carnival “knew or ought to have known” about the “significant risk” of an outbreak with potentially “disastrous” consequences, yet it proceeded “regardless” and that any “reasonable person” would have cancelled the cruise.

Speaking outside the court, Mrs Karpik remembered the 28 people who lost their lives following the outbreak, saying many “would have been celebrating a significant event in their lives” in taking the cruise.

There had been an outbreak of an “influenza-like illness” on a voyage taken immediately prior to the trip, the judge said in his ruling. That voyage had ended early on 8 March 2020, and had raised the risk of the virus being carried over to the next trip, he added.

The ruling is the first class action win against a cruise ship in the world, according to Shine Lawyers.

The number of claimants could also grow should Australia’s High Court rule 700 American passengers can be included in the class action lawsuit.

The voyage was for a time Australia’s biggest single source of Covid infection and a public inquiry into the outbreak concluded health officials in the New South Wales state made “serious mistakes”.

Carnival Australia said it was considering the judgement in detail.