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A member of the Australian government’s advisory group on infection control has defended the decision not to recommend the use of N95 masks in all settings in hotel quarantine, saying that – with the exception of the Holiday Inn outbreak – most of the recent outbreaks in the quarantine system can be explained as droplet transmission.
Prof Peter Collignon, a member of the Infection Control Expert Group (ICEG), which advises the Australian Health Protection Principal Committee on infection prevention and control measures, including use of personal protective equipment (PPE), said there was no evidence to suggest aerosol transmission was in play in Australian quarantine hotels outside of the case at the Holiday Inn, where a nebuliser was used which caused aerosolised particles that apparently dispersed through the hallway.
“The use of the nebuliser produces aerosols there’s no doubt about that,” Collignon said. “And it explains why there’s a bigger cluster. All the others are one-offs, which in my view is more a reflection of poor eye protection rather than because they’re aerosols.”
It follows a push by the Australian Medical Association (AMA) for the national guidelines to be updated to recognise the risk of aerosol spread in hotel quarantine, including requiring workers to wear an N95 mask and goggles while on a floor where potentially infectious guests are staying.
The Holiday Inn outbreak now stands at 13 cases, with five more reported on Thursday. In contrast, the local transmission event at Melbourne’s Grand Hyatt Hotel and the Park Royal Hotel were both limited to one case, as was the hotel quarantine outbreak in Perth. The Brisbane outbreak was contained to two people – a cleaner at a quarantine hotel and their spouse.
Collignon said that while in a number of those cases it appeared the virus was transmitted by air, that did not, in epidemiological terms, mean the virus was airborne. Aerosol transmission refers to very small particles, about five microns across, which can both travel a long distance and remain in the air for a long time.
“In other words, if they get into your air conditioning they will go through your whole building,” he said.
Whereas droplets travelling by air are bigger particles which travel shorter distances and dissipate more quickly. In a still room, they do not travel more than two metres. But in a positive pressure environment – such as someone opening the door to a hotel room, which has air conditioning blowing, into a hallway with no air conditioning – they can travel much further, he said. That is what experts believe happened in Western Australia and in the two earlier outbreaks in Melbourne hotels, where the virus transmitted across a hallway.
“The reality is both [particle types] are produced, they are both there,” Collignon said. “I think all the available data in the community suggests that the vast majority of spread is via droplets because when you look at outbreaks it’s people in close proximity, people not wearing masks, all those sorts of things,” he said. “That’s why the CDC, the World Health Organisation, all the authorities say the majority of spread seems to be droplets.”
Collignon said the debate, which has been raging between the AMA and the ICEG since July, was partly definitional. “My view is most of Covid is airborne, so it goes through the air, the trouble is ‘airborne’ has a meaning,” he said.
He supports many of the measures called for by the AMA, including doing an engineering review of hotels to create negative air pressure in the hallways and allowing people access to windows which can be opened, the cheapest and easiest way to reduce the risk of virus particles flowing out of a room into an internal hallway.
Dr Omar Khorshid, the president of the AMA, said the debate had been “very frustrating” for many doctors.
“Clearly this focus on droplet protection isn’t enough which is exactly what happened in Victorian hospitals last year,” he said. Some 3,561 Victorian healthcare and aged care workers have contracted Covid-19 to date, mostly during Victoria’s second wave. Some 73% caught it at work.
“We strongly believe that there’s enough evidence now to move to airborne protection to anybody who could have contact with somebody with Covid,” Khorshid said.
The ICEG said in October that it has “consistently recognised the potential for transmission of SARS-CoV-2 via aerosols in specific circumstances” but that evidence suggests it is mainly transmitted via droplets. It recommends the use of a particulate filter respirator (a P2 or N95 mask) in specific circumstances in healthcare settings.
Khorshid said the process for getting new national guidelines on mask use, which began in September, and, the AMA hopes, will put more emphasis on the risk of aerosol spread, was “painfully slow”.
He acknowledged that the advice from experts was mixed. “This is an argument about science and there are scientists on both sides of this debate,” he said.
The Victorian government is now considering requiring the use of N95 masks in some hotel quarantine settings.
“It’s only a matter of time that one of these events turns into another catastrophe, the need for another lockdown or another big community outbreak, both of which I think will be very disappointing to the Australian people when it could have been prevented by taking some of these simple measures,” Khorshid said.
Source: The Guardian
Keyword: Melbourne Covid cluster: decision not to recommend N95 masks in hotel quarantine defended | Health