Here is the timeline which led to dozens of people with Covid-19 being allowed to disembark in Sydney

Anatomy of a coronavirus disaster: how 2,700 people were let off the Ruby Princess cruise ship by mistake

On Thursday, the Ruby Princess cruise ship docked in Sydney harbour after an 11-day round trip to New Zealand.

Despite the ship previously logging 158 cases of illness on an earlier voyage, all 2,700 passengers on board were allowed to disembark at Sydney’s Circular Quay and return to their homes in New South Wales and interstate.

So far, 133 people have been diagnosed with the disease after leaving the ship, and one person, a woman in her 70s, has died.

The NSW health minister, Brad Hazzard, admitted on Sunday that this was a mistake to let passengers disembark, and on Monday the prime minister, Scott Morrison, said the Australian defence force had been called in to help NSW Health track the passengers’ contacts.

How did a public health disaster like this happen?

Coronavirus in Australia: 26 infections from Ruby Princess contribute to largest daily rise in cases Read more

Sunday 8 March

The Ruby Princess arrived in Sydney on 8 March, having sailed from Port Chalmers in New Zealand on a previous tour.

According to the ship’s internal logs, 158 passengers on board were sick, with 13 registering high temperatures. Nine were tested upon arrival, according to the Australian newspaper. However, all passengers were allowed to disembark, including a Northern Territory couple who flew to Darwin, and later tested positive for Covid-19.

The ship was rated “medium risk” by NSW Health as a result of the 158 cases of illness.

Hours later, 2,700 new passengers boarded the ship in Sydney, and it set sail that night for another return trip to New Zealand.

Monday 9 March – Saturday 14 March

According to ship tracker Marine Traffic, the Ruby Princess docked in Port Chalmers on Thursday 12 March, Wellington on Saturday 14 March and Napier on Sunday 15 March.

Five people developed “influenza-like illness” by Wellington on 14 March, NSW Health revealed a week later on Friday 20 March. They tested negative for Covid-19 “at that time”, NSW Health said.

Sunday 15 March – Wednesday 18 March:

On Sunday 15 March, the Ruby Princess left Napier and set a course for Sydney – 63% of the passengers were Australian residents, 20% were American residents and the remaining 17% were from other countries.

Elisa Mccafferty, a passenger on the ship, told Guardian Australia that people were told to fill in a form declaring if they had a cough or fever, but at no point did the Ruby Princess inform passengers that there were suspected cases of coronavirus on board.

Thursday 19 March

The Ruby Princess arrived in Sydney harbour. All of its 2,700 passengers were allowed to disembark at Circular Quay, with many heading immediately to domestic flights.

Despite being deemed “medium risk” a week earlier, the ship was deemed “low risk” that day because it had only travelled between New Zealand and Australia.

One passenger was unwell and taken directly from the ship to hospital, two presented to Sydney hospitals for testing after disembarking, and one was a crew member who was placed into isolation on the ship.

All four would later test positive for Covid-19, but the results of these tests would not be disclosed until Friday. The woman who was taken directly to hospital died on Tuesday morning.

Passenger Bill Beerens would later tell the ABC that he had a cough when he left the ship on Thursday, but was allowed to go home without testing. He went to a hospital that night and his test came back positive on Saturday.

He said other passengers near him also had coughs and sore throats.

Mccafferty said: “At no point was anybody checked. As we were disembarking, they basically just scanned us off in groups. And we were let go. We didn’t see any temperature scanning, nobody was pulled aside that we could see.”

All passengers were told they would need to self-isolate at home or in a hotel for 14 days.

Friday 20 March

NSW Health announced that four passengers from the ship had tested positive, but all had disembarked and had already started journeying home, including interstate.

The health department said they began calling passengers, emailing and texting to inform them of the confirmed cases, and remind them to self-isolate and monitor for symptoms.

A spokesman for Princess Cruises told Guardian Australia that “our onboard medical team was rigorous in its treatment of some guests who reported flu-like symptoms, and these guests were isolated.

“The ship reported these cases to NSW Health, which in turn requested swabs to be provided following the ship’s arrival in Sydney, some of which subsequently tested positive for Covid-19.”

NSW Health did not respond in time for publication about what assessments they conducted on passengers, and whether they knew if any passengers had symptoms of Covid-19.

On Tuesday 24, the department said in a public statement that “no cases of Covid-19 had been identified by doctors on board before docking”.

Saturday 21 March

Hazzard admitted that it was a mistake to allow the 2,700 passengers to disembark on Thursday without testing.

“If I had my opportunity to have my two bob’s worth, with the benefit of what we now know about those … people, I’d have said yeah, maybe we should hold them on the ship,” he told reporters.

Sunday 22 March

The number of confirmed cases from the Ruby Princess rose to 26 in total – 18 in NSW and eight interstate.

Monday 23 March

The number of confirmed cases from the ship rose to 48 in total – 27 in NSW, and 21 interstate.

Morrison told parliament that NSW Health was responsible for allowing the passengers to disembark, and that the Australian Defence Force had been called in to help the department trace the contacts of the infected passengers.

“The vessel was placed under the control of the NSW authorities including NSW Health and the NSW port authority,” he told parliament. “NSW Health has stated it undertook a full assessment of the Ruby Princess and allowed passengers to disembark.

“Yesterday the ADF provided assistance to the NSW health department to provide contract tracing support​ [and] contact tracing activities relating to passengers from this vessel.”

In a statement, the defence minister, Linda Reynolds, said ADF contact tracing support teams were “being established in all states and territories”.

Tuesday 24 March

The number of confirmed cases from the ship rose to 133 in total – 107 in NSW, and 26 interstate.

A woman in her 70s, who was among the first four who tested positive, died in a Sydney hospital.