The Pullman Hotel managed isolation facility is fully reopening after a report finds respiratory particle transmission was the most likely way returnees were infected with Covid-19.
The Pullman Hotel managed isolation facility in Auckland. Photo: RNZ / Dan Cook
The Auckland facility was closed after three guests tested positive for the virus in separate incidents in January, then operated at a 50 percent capacity.
An independent report into the facility was unable to conclude with "absolute certainty" how transmission occurred, but it was likely to be airborne.
Transmission in at least two cases was most likely through exposure to aerosols in a lift or in relation to a lift lobby; both shared spaces that were confined, congested and poorly ventilated, the report said.
In one case, a returnee's room appeared to have been the most likely location of aerosol transmission due to the particular orientation of the door of this room in relation to the lift lobby.
The report described the Pullman Hotel as a non-purpose-built facility with confined, poorly ventilated shared spaces.
The review said so far the focus had been on minimising potential droplet spead, which meant there had been little public health guidance geared to the prevention of aerosol transmission.
Some immediate changes were made at the Pullman Hotel after the infections. It had been operating at 50 percent capacity and introduced a booking system for exercise and smoking areas as well as the installation of CCTV in corridors and lobbies.
All MIQs have made changes to improve the prevention of airborne transmission. Air purifiers had been added to lifts and corridors, and there was wider use of N95 masks for workers who have close interaction with returnees.
Director of Public Health Dr Caroline McElnay said the risk of staff and returnees catching the virus within the facilities was, and still is, extremely low.
"One of the things we are becoming more aware of is aerosol transmission and the need to ensure spaces are well ventilated to mitigate that risk," Dr McElnay said in a statement.
Joint head of managed isolation and quarantine Brigadier Jim Bliss said work was already underway looking at respiratory particle transmission and the role of ventilation systems but was pushed through for the Pullman after the January transmission events.
"The ventilation work undertaken at the Pullman was to get the Heating Ventilation and Air Conditioning (HVAC) system operating as originally designed.
"It is important to remember that up until March 2020, these facilities were operating as hotels not managed isolation and quarantine facilities, but when vulnerabilities are identified we need to address them to ensure the continued safety of staff and returnees."
Remedial work at the facility included cleaning all ducts, ensuring risers between floors were properly sealed and checking fans were putting out required air volumes.
Air supply on floors where guests were was also brought up to standard.
The Pullman will be the first facility to start the cohort system where new returnees are only allowed in after the last cohort have completed their stay and facilities have been cleaned.