Thirteen Ruby Princess cruise passengers unknowingly spread COVID-19 on a five-hour flight to Perth to at least eight others after NSW Health allowed the ship to disembark in Sydney.

The new findings will be published by a group of Western Australia researchers in the Emerging Infectious Diseases journal next month.

According to the Sydney Morning Herald, the researches have used genomic sequencing to identify how 29 of the passengers of the Qantas flight, who would later test positive for the virus, contracted COVID-19.

Research shows that at least eight, or most likely up to 11 were contracted on board the flight which was carrying at least 60 passengers from the Ruby Princess as well as Royal Caribbean’s Ovation of the Seas.

The report also says that of the 28 Ruby Princess passengers who had boarded the flight just hours after disembarking the ship. And the researchers found 13 were carrying the virus and 11 were infectious.

Qantas medical director Ian Hosegood told the Sydney Morning Herald that the findings confirmed the only example of transmission on a Qantas flight and he said he was frustrated that the airline was unaware at the time that cruise passengers who posed a COVID-19 risk would be on the flight.

“We had no idea that at least 60 passengers had come off the Ruby Princess and other ships where COVID was already spreading. Had we known, they would have been stopped from travelling,” Dr Hosegood said in a statement.

“As has been established by the special inquiry, the moment Qantas became aware that Ruby Princess passengers had been released and were travelling by air, we asked repeatedly for the manifest in a bid to stop these same passengers boarding any of our domestic or international flights. But we were told by the Department of Health that the manifest could not be provided for privacy reasons.

Dr Hosegood noted Qantas also had operated a repatriation flight for Australians who were stranded off Japan on the Diamond Princess and that there was no transmission on that flight with strict infection control protocols in place.

“It’s fair to say a lot of lessons have been learnt and community confidence in flying shouldn’t be diminished because of what was an exceptional and preventable set of circumstances early in the pandemic.”