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 Professor Tarum Weeramanthri in his 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 at the Sheraton Four Points hotel contracted the UK variant of COVID-19 then unwittingly roamed the streets while infectious, though his case 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," Prof Weeramanthri told reporters on Friday.
He recommended every hotel room being used for quarantine be inspected for airflow and that hotel quarantine workers should undergo increased testing. He also advocated for full PPE for all staff.
The WA health department has already begun ventilation assessments, Chief Health Officer Andy Robertson said in the same press conference on Friday, starting with the Sheraton Four Points hotel.
"There are a number of rooms, including the room where the person who likely infected 903 was in that we will probably exclude," Dr Robertson said.
"Other rooms, they were happy with airflow."
The young security guard, who had been stationed in a hallway, 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, despite it being the highly contagious UK variant of the virus.
The incident placed scrutiny on WA's hotel quarantine safeguards and led to changes including barring some workers from holding second jobs.
The guard, an international student aged in his 20s and known as "case 903", returned home on Sunday after three weeks in quarantine.
WA Health said he had chosen to stay beyond the mandatory 14 days after becoming unwell with an unrelated condition.
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.
Authorities believe the virus was transmitted either by airborne transmission or surface contamination.
WA has managed 38,000 guests through hotel quarantine, including more than 500 positive virus cases.
