The government is being urged to stop using any hotels with sub-par ventilation for managed isolation so it can prevent Covid spreading between unwitting guests.
Health officials are investigating how the Northland woman whose case has sparked a major community response caught the virus from another guest - including whether it was through the ventilation system.
Auckland University professor of medicine Des Gorman said, though ventilation transmission was unlikely, it was possible because some hotels had systems that allowed droplets to spread to other rooms.
The government needed to employ ventilation engineers to investigate, he said.
"They should be called upon right now to have a look at the various hotels and identify those which are suitable and those which are not suitable," he said.
It should stop using any that could aid the spread, he said.
The government was already looking into some aspects of hotel air conditioning after a managed isolation outbreak in Brisbane suspected to have been spread by air con.
The Ministry of Health said it would look specifically at the Pullman's system to see if it could have played a role.
It was interviewing both guest in detail and was also considering whether the virus was spread through airborne particles in other areas, or from droplets on surfaces.
Infectious diseases expert David Murdoch said the cause of the latest infection may never been known but a thorough investigation of all possibilities was important.
That could lead to any vulnerabilities in the managed isolation system being uncovered and fixed.
And he supported the idea of taking any hotels out of the MIQ mix if they had ventilation systems that might aid the spread.
"While it may be difficult to prove one way or the other whether one particular system is linked to transmission ... having a well-maintained system that avoids circulating air to where there are other people certainly makes a lot of sense," he said.
And both professors backed the plan the government was considering to keep guests who had their final day-12 test separate from new arrivals to prevent infection.
They said everything practical must be done to make the isolation system as safe as possible.
Professor Gorman said many of the problems would be solved by having purpose-built facilities outside of highly-populated areas would be far safer and solve many problems - and it was not too late to build them, he said.
"This is not a bizarre and unusual event - we had SARS 1, SARS 2, we had MERS. This is simply the latest pandemic in a series of pandemics and I think we'd be incredibly naive to think when we get through this particular pandemic we're going to have a hundred years of happiness," he said.
The health ministry said it gave the government new advice on air-conditioning and ventilation next week but was not ready to share that publicly yet.
Advice from the Ministry of Health:
- There are now over 30 locations of interest listed on the Ministry of Health website.
- If you were at the locations of interest at the times stated, you need to; isolate away from others, call Healthline 0800 358 5453 for advice on when and where to get tested, and remain isolated until you have a negative test result.
- If you were not at a location of interest at the stated times and you have no symptoms you do not need to be tested.
- If you were not at any of the locations of interest at the stated times, but you have symptoms, call Healthline for advice on 0800 358 5453
- If you recently arrived in New Zealand and stayed in managed isolation at the Pullman Hotel between 9 January and 24 January, please Isolate away from others, call Healthline 0800 358 5453 for advice on when and where to get tested, and remain isolated until you have a negative test result.
- If you are going to get tested, remember you may have to queue. Please take food and water and continue to be kind to each other and our public health team.
- Remember our hospitals are extremely safe. People who need urgent healthcare (including non-COVID) please continue to call 111 or go to the Emergency Department
- Everyone should continue to scan QR codes using the COVID Tracer app and turn Bluetooth on to help stop the spread of Covid-19.