Airflow assessments of hotel quarantine rooms are underway in Western Australia as a result of a review into how a guard contracted COVID-19 from an infected person with whom he never had contact.
The checks are a recommendation from an interim investigation into the adequacy of the state's hotel quarantine system, prompted by the single locally transmitted case in January that caused a five-day lockdown of Perth and surrounds.
The security guard, now known as "case 903", at the Sheraton Four Points hotel contracted the UK variant of COVID-19 then unwittingly roamed the streets while infectious, though he did not cause an outbreak.
"Given established evidence for airborne transmission, the particular circumstances of case 903 as well as similar cases in other states, ventilation must now be seen as a key modifiable risk factor for transmission in a hotel quarantine environment," said Professor Tarum Weeramanthri, who conducted the review.
He recommended every hotel quarantine room be inspected by experts for airflow and that on-site staff undergo increased testing. He also advocated for full PPE for all staff.
Ventilation assessments have already begun, Chief Health Officer Andy Robertson said in the same press conference on Friday, starting with the Sheraton Four Points hotel.
He said some rooms would no longer be used as a result of the assessment, "including the room where the person who likely infected 903 was in".
Dr Robertson said the room closest to where the guard had been was more exposed to the sun, so the occupant may have turned up the air-conditioner, increasing airflow in the room.
He said more CCTV cameras would be added onto the floors of quarantine hotels, in addition to in-person security.
The young security guard, who had been stationed in a hallway and several metres from the door of a room housing a positive case, was WA's first case of local transmission in nine to 10 months.
A testing blitz produced no evidence of other infections in the community.
The incident placed scrutiny on WA's hotel quarantine safeguards and led to changes including barring some workers from holding second jobs.
Dr Robertson commended the guard, who is now back home, and his house mates for their cooperation, saying they had done everything right.
Questions remain over how he contracted the virus.
The guard is not believed to have had any face-to-face contact with the infected person in the nearby hotel room.
Prof Weeramanthri said it was plausible that airborne transmission could have occurred via airflow under the hotel room door.
He emphasised the state's overall success in protecting the public from the pandemic, citing statistics of 38,000 guests through hotel quarantine, including more than 500 positive virus cases.
"The WA public can have trust in a system which has delivered excellent outcomes so far and is committed to learning and continuous improvement," he said.
Australian Associated Press