A guest in Melbourne’s hotel quarantine system was positive with COVID-19 when they used a nebuliser, believe experts, who say every second they used the machine they would have been releasing up to 10,000 times more aerosol particles than if they were breathing normally.
And that would have given SARS CoV2 — the virus that causes COVID-19 — millions more droplets to “hitch a ride” on.
- The Victorian Government says it is investigating the possible spread of coronavirus via a nebuliser
- The medical device is designed to vaporise medicine and deliver a concentrated dose to the user’s lungs
- Experts warn a contaminated nebuliser would become a “generator of SARS-CoV2” — the virus that causes COVID-19
According to senior lecturer in mechanical and aerospace engineering at Monash University Daniel Duke, a nebuliser does not make the virus more potent, travel further or hang around in the air longer.
“There is simply more opportunity for the virus to be transmitted by aerosol,” he said.
The use of the device is being investigated by Victorian Health Authorities, with the number of cases linked to the Melbourne Holiday Inn outbreak now at 10.
Victoria’s Chief Health Officer Brett Sutton said at least three of those were believed to be linked to the use of the nebuliser.
Experts say it is a step forward that health authorities are acknowledging the aerosol spread of SARS CoV2 — the virus that causes COVID-19 — but insist more needs to be done to protect those working among it.
A nebuliser is a medical device designed to vaporise medication for users to inhale, sending a concentrated dose straight to their lungs.
Someone using a nebuliser attaches a mask to their face and breathes in and out, but a device can become contaminated if the user is shedding a virus at the time.
Dr Duke said the whole point of a nebuliser was to deliver as many aerosol droplets to the lungs as possible.
“The problem with nebulisers is that they … are purposefully designed to produce thousands of times more aerosol than natural breathing,” he said.
“When someone inhales a nebuliser mist, it goes into their lungs and then they breathe a lot of it back out again.
“A substantial portion of that aerosol has been in contact with the person’s upper airway.
‘This is a very unlikely coincidence’
Dr Duke said even though someone using a nebuliser breathed through a mask, some of the mist escaped.
“A lot of the aerosol from the nebuliser will naturally escape into the room — far more than would naturally be emitted by normal breathing,” he said.
“Unlike nebulisers used in hospitals … the cheaper ones from pharmacies, that you might use at home or in a hotel, they just pump that stuff straight out into the room. They don’t filter it at all.”
Nebulisers, as well as other vaporising devices, are banned in general hotel quarantine, according to Victorian health authorities.
However, authorities said they were unable to search guests’ luggage and some did not realise their medical devices were a transmission risk.
Problematic devices include nebulisers, aromatherapy diffusers and CPAP machines, used to help people with sleep apnoea.
Dr Duke said vaporising medical devices were often essential treatments.
“It’s a huge problem … because you’ve got people with genuine lung disease who absolutely must use nebulisers and, if they’re COVID-19 positive and they’re shedding the virus, they can’t stop using the nebuliser,” he said.
Late last year, the French Society of Respiratory Disease warned nebulisers were a likely source of COVID-19 transmission.
The paper, which investigated healthcare worker safety, warned a nebuliser could “operate like a generator of SARS-CoV2 aerosol with a perfect particle size to travel long distances and to penetrate into healthcare worker upper and lower airways”.
The authors recommended workers wore a P2 mask, disposable gown, protective glasses and a hat that completely covered the hair for “three hours following the nebulisation session”.
Further calls for P2 masks
Occupational hygienist Kate Cole said it was “good” the nebuliser hypothesis “considered and recognised aerosol spread and airborne transmission” of COVID-19.
“It confirms that airborne precautions are needed for those people who service hotel quarantine,” she said.
“They need an N95 P2 respirator [mask] that is fit tested for the person wearing it, with adequate training provided.
“Unfortunately, until we get N95 respirators out to hotel quarantine workers and surgical masks are replaced, we should expect to continue to see these types of outbreaks occur.
“Wearing an N95 or P2 mask would absolutely protect you against the virus spread by a nebuliser.”
Victoria’s COVID-19 hotel quarantine commissioner Emma Cassar said some people in the state’s hotel quarantine system had been using N95 masks, but mandatory widespread use would now be considered.
“If we had used N95 masks from the start, you potentially could argue we wouldn’t have had the cases we’ve had in the past couple of days,” she said.
Ms Cassar did say one of the hotel workers infected in Melbourne in the past week had been wearing an N95 mask “and was infected anyway”.
Victoria’s Deputy Chief Health Officer Melanie Van Twest said this was “not as simple as putting N95s on a desk and saying, ‘Here people — wear them.'”
“The last thing we want is to have people in N95s without all the protective strategies like fit checking and fit testing, moving masks around, and creating a greater risk,” she said.
Calls for national advice to change
Dr Duke said nebulisers were used extensively in hospitals and the risk in those settings was “carefully managed”.
“The same cannot be said for other environments like hotels,” he said.
Australia’s hotel quarantine system has been hailed as the best line of defence against COVID-19, but also the source of most outbreaks seen in recent months.
The virus can escape the system, as seen in Queensland, New South Wales, Western Australia and now twice in Victoria.
Experts have long warned the grade of PPE used by hotel workers is not adequate, arguing safety measures should be similar to hospitals.
The group responsible for advising the Federal Government on hotel quarantine, the Infection Control Expert Group (ICEG), had indicated it would update its position on aerosol spread.
A spokesperson for the federal Department of Health said stronger infection control protocols were being considered.
“Members of the Australian Health Protection Principal Committee, as well as members of ICEG and Communicable Disease Network Australia, are currently considering strengthened national guidance for states and territories on hotel quarantine, which will include consideration of the hierarchy of controls to prevent and control the transmission of infection,” the statement said.
“This guidance to states and territories is currently under development and is taking into account the available evidence including the anecdotal reports of transmission in quarantine hotels.”
On Wednesday, the Australian Medical Association (AMA) released a statement calling for the national advice to change now.
“It’s most likely that these cases are the result of airborne spread, yet the experts advising government, the ICEG, have continually played down airborne transmission in the spread of the virus in hotel and healthcare settings,” AMA president Omar Khorshid said.
“The AMA and much of the wider medical profession have been calling for better responses to the risk of airborne spread of COVID-19 for months.
“[The] news regarding the Holiday Inn is more evidence that these calls should have been heeded earlier.”