Federal border authorities have blamed NSW Health for the Ruby Princess cruise ship fiasco, arguing the department gave the key "green light" for disembarkation.
More than 130 passengers from the ship, which berthed in Sydney last week, have since been confirmed as having COVID-19.
About 13 passengers showed respiratory symptoms before disembarkation at 6am on Thursday, with three of them subsequently testing positive for the virus.
One passenger, a 77-year-old woman, has since died.
Operator Princess Cruises last week said everyone who had developed symptoms had been in isolation on board.
NSW Chief Health Officer Dr Kerry Chant says most infected passengers hadn't displayed symptoms until the day they left the ship or later.
There was little health authorities could do to prevent the disembarkation of asymptomatic cruise passengers, she said on Wednesday.
Dr Chant added health authorities in New Zealand, where the cruise ship visited, had checked the Ruby Princess for COVID-19.
Australian Border Force chief Michael Outram on Wednesday insisted his organisation was responsible only for checking for contraband and ensuring orderly migration.
They were two of three "green lights" required before passengers could disembark.
The third biosecurity green light was given by federal agricultural authorities and NSW Health, which had decided not to conduct additional checks on the "low risk" vessel.
"The decision to allow them off in relation to the health and biosecurity issue was one of NSW Health," Mr Outram said.
"I'm not here to apportion blame, we are all in it together in Australia ... but the public needs to know the facts. My officers are not trained to take temperatures."
The Australian newspaper reported on Tuesday that NSW Premier Gladys Berejiklian told colleagues the fiasco was caused by ABF miscommunication.
Dr Chant said a report would be commissioned on the decision to allow passengers to disembark without stronger vetting.
The ship remains off the NSW south coast with about 1100 crew on board. Princess Cruises has been contacted for comment.
"Those passengers recognising symptoms have been infected on the ship and no action by NSW Health or otherwise could alter that," Dr Chant said on Wednesday.
"What we're working on now is to identify any onwards transmission from any contact from those people travelling home."
There have been multiple confirmed coronavirus outbreaks on cruise ships across the globe, with other Australian cases linked to the recently docked Ovation of the Seas.
The furore over the Ruby Princess follows the Australian government being forced to rescue citizens off the Diamond Princess in Japan, with one Perth man later dying from the virus.
Mr Outram admitted he could lose up to 40 per cent of his staff amid the crisis as they fall ill or are required to care for relatives.
Prime Minister Scott Morrison said the Ruby Princess situation was "terrible" and federal authorities were working with NSW on contact tracing.
Opposition home affairs spokeswoman Kristina Keneally on Wednesday said Australia would reflect on the Ruby Princess debacle as a pivotal moment in the crisis.
"The reality is people were allowed to get off a cruise ship," Ms Keneally said.
"The border security measures that the commonwealth government put in place failed the Australian people."
Australian Associated Press