At last, health, aged care and quarantine workers get the right masks to protect against airborne coronavirus


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C Raina MacIntyre, UNSW; Benjamin Veness, CQUniversity Australia, and Michelle Ananda-Rajah, Monash UniversityAlmost a year ago, in July 2020, our calls for the government to urgently upgrade the guidelines to protect health workers from airborne SARS-CoV-2 fell on deaf ears.

The existing guidelines said health providers working around COVID-19 patients should wear a surgical mask. It restricted use of the more protective P2 or N95 masks, which stop airborne particles getting through, to very limited scenarios. These involved “aerosol-generating procedures”, such as inserting a breathing tube. This was expanded slightly in August 2020 but still left most health workers without access to P2/N95 masks.

More than 4,000 Australian health workers were infected by COVID-19 during the Victorian second wave. Health authorities denied the importance of airborne transmission and blamed clinical staff for “poor habits” and “apathy”. Health workers expressed despair and a sense of abandonment, cataloguing the opposition they faced to get adequate protection against COVID-19.

Last week, 15 months after the COVID-19 pandemic was declared, the Australian guidelines on personal protective equipment (PPE) for health workers, including masks, were finally revised.

What do the new guidelines say?

The new guidelines expand the range of situations in which P2/N95 masks should be available to staff – essentially anywhere where COVID-19-infected people are expected to be – and remove all references to “aerosol-generating procedures”.

This recognises that breathing, speaking, sneezing and coughing all generate aerosols which can accumulate in indoor spaces, posing a higher risk than “aerosol-generating procedures”.




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“Fit testing” is an annual procedure that should be done for all workers wearing a P2/N95 mask or higher grade respirator, to ensure air can’t leak around the edges.

But this was previously denied to many Australian health workers.

The new guidelines unequivocally state fit-tested P2/N95 masks are required for all staff managing patients with suspected or confirmed COVID-19. This means health workers can finally receive similar levels of respiratory protection to workers on mining and construction sites.

The new guidelines leave ambiguity around which workplaces are within the scope by stating that health care:

may include hospitals, non-inpatient settings, managed quarantine, residential care facilities, COVID-19 testing clinics, in-home care and other environments where clinical care is provided.

The guidelines also allow employers to decide what comprises a high risk and what doesn’t, allowing more wiggle room to deny workers a P2/N95 mask.

N95 and surgical masks on a table.
N95 masks (top) protect against airborne transmission, while surgical masks (bottom) don’t.
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The guidelines say when a suitable P2/N95 mask can’t be used, a re-usable respirator (powered air purifying respirators, or PAPRs) should be considered.

But the guideline’s claim that a PAPR may not provide any additional protection compared to a “well-sealed” disposable P2/N95 mask, is not accurate. In fact, re-usable respirators such as PAPRs afford a higher level of protection than disposable N95 masks.

The new guidelines should also apply to workers in hotel quarantine – both health care and non-clinical staff. This will help strengthen our biosecurity, as long as they’re interpreted in the most precautionary way.

That means not using the wiggle room that allows workplaces to deem a situation lower risk than it actually is or that their workplace is exempt. When working around a suspected or confirmed COVID-19 case, all workers must be provided with a fit-tested P2/N95 mask. Otherwise they are not protected from inhaling SARS-CoV-2 from the air.

In aged care and health care, where cases linked to quarantine breaches can be amplified and re-seeded to the community, the new guidelines go some way towards better protecting our essential first responders and their patients.




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Guidelines miss the mark on ventilation

The guidelines fail to explicitly acknowledge COVID-19 spreads through air but nonetheless recommend the use of airborne precautions for staff.

Airborne particles are usually less than 100 microns in diameter and can accumulate indoors, which means they’re an inhalation risk.

The old guidelines focused on “large droplets”, which were thought to fall quickly to the ground and didn’t pose a risk in breathed air. This was based on debunked theories about airborne versus droplet transmission.

The new guidelines fail to comprehensively address ventilation, which is only mentioned in passing with a reference to separate guidelines for health-care facilities. This may not cover aged care or hotel quarantine.




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We must ensure institutions such as hospitals, hotel quarantine facilities, residential care, schools, businesses and public transport have plans to mitigate the airborne risk of COVID-19 and other pandemic viruses through improved ventilation and air filtration.

Australia could follow Germany, which has invested €500 million (A$787 million) in improving ventilation in indoor spaces.

Meanwhile, Belgium is mandating the use of carbon dioxide monitors in public spaces such as restaurants and gyms so customers can assess whether the ventilation is adequate.

Cleaning shared air would add an additional layer of protection beyond vaccination and mask-wearing. Secondary benefits include decreased transmission of other respiratory viruses and improved productivity due to higher attention and concentration levels.

No updated advice on hand-washing

The United States Centers for Disease Control and Prevention (CDC) now acknowledges exposure to SARS-CoV-2 occurs through “very fine respiratory droplets and aerosol particles” and states the risk of transmission through touching surfaces is “low”.

Yet this is not acknowledged in the latest Australian health-care guidelines.

Australians have been repeatedly reminded to wash or sanitise their hands, wipe down surfaces and stand behind near-useless plexiglass barriers.

The promotion of hand hygiene and cleaning surfaces is not based on science, which shows it is the air we breathe that matters most.

Revised public messaging is needed for Australians to understand shared air is the most important risk for COVID-19.The Conversation

C Raina MacIntyre, Professor of Global Biosecurity, NHMRC Principal Research Fellow, Head, Biosecurity Program, Kirby Institute, UNSW; Benjamin Veness, Adjunct Professorial Fellow, CQUniversity Australia, and Michelle Ananda-Rajah, Consultant physician General Medicine & Infectious Diseases, Alfred Health, past MRFF TRIP Fellow, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Is the airborne route a major source of coronavirus transmission?



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Hassan Vally, La Trobe University

As the world continues to grapple with the coronavirus pandemic, one question that keeps coming up is whether COVID-19 can be transmitted through the air.

In fact, 239 scientists in 32 countries have written an open letter to the World Health Organisation (WHO) arguing there is mounting evidence the airborne route plays a role in the transmission of COVID-19.

Like a lot of issues to do with the pandemic, what seems to be a relatively straightforward question is deceptively complex. We actually don’t know the answer for sure.

Why do we need to understand the modes of transmission?

Understanding how COVID-19 is transmitted from one person to the next enables us to design effective public health interventions to minimise the risk of transmission.

For instance, we’re advised to keep 1.5 metres away from others because there’s consensus one of the main ways the virus spreads is via large droplets.

These “large” droplets are usually greater than 5 micrometres in size and are propelled from an infected person’s nose or mouth in their mucus and saliva when they sneeze, cough or talk.

Thanks to gravity, these large droplets don’t generally travel far before landing. If you position yourself more than 1.5 metres from someone who is infected, the expectation is you’ll be clear of the droplets’ path.




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Similarly, understanding these large droplets can land on surfaces and that the virus can survive on these surfaces means we know we need to wash our hands to avoid transferring the virus to our mouth, nose or eyes.

Until now, the WHO has maintained these large droplets are the major source of COVID-19 transmission. But the authors of the open letter suggest they are underplaying the role of airborne transmission.

Airborne transmission and COVID-19

In its simplest interpretation, airborne transmission refers to the ability of a virus to be spread by droplets small enough to be suspended in the air. These droplets are less than 5 micrometres in size and generally called aerosols.

Whereas large droplets can only travel short distances, these smaller droplets, in theory, can be spread further, or can linger in a room even after an infected person has left.

COVID-19 spreads when an infectious person emits tiny virus-containing droplets.
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Evidence supporting the notion that transmission of COVID-19 can occur via the airborne route takes several forms.

First, laboratory studies have demonstrated that SARS-CoV-2, the coronavirus that causes COVID-19, can be aerosolised, and can survive for up to four hours in this form.

Second, genetic material from SARS-CoV-2 has been detected in aerosols sampled at hospitals, including two hospitals in Wuhan, the Chinese city from which the pandemic emerged. But it’s important to note the presence of this genetic material doesn’t necessarily mean the virus is infectious in this form.




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Perhaps the strongest evidence, however, comes through the various case reports of superspreading events. These are situations in which many people appear to have been infected with coronavirus in the absence of close contact.

One notable early example was from a choir practice in the United States where almost 50 people were infected even though they maintained physical distance. Two died.

Another example is an outbreak in Guangzhou, China, where ten people from three families contracted COVID-19 after dining in a restaurant. Non-infected people were not in close contact with any infected person, but those who became infected were in the direct line of one air conditioning unit.

The study of this outbreak is not yet peer-reviewed but is part of the evidence the authors of the open letter draw on.

What are the implications of airborne transmission?

Airborne transmission of this novel coronavirus is potentially a worry, because if it occurs often, it means the virus may be commonly transmitted in the absence of close contact.

It also raises the possibility the virus may travel on air currents, and even be transmitted through air conditioning.

This means social distancing may not always be effective, and in particular, crowded indoor areas with poor ventilation pose a major threat.

Good ventilation could lower the risk of airborne transmission in indoor spaces.
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So where does this leave us?

The key question is not whether airborne transmission is theoretically possible; it certainly is. But rather, how significant is its role in the transmission of COVID-19?

If, for example, most transmission of SARS-CoV-2 happens via large droplets and the airborne route plays a role only occasionally, this has very different implications to a scenario where the airborne route is a significant mode of transmission.

Reassuringly, the interventions that have been implemented to limit spread of the virus, such as social distancing, have been largely successful so far in most of Australia. This suggests even if the virus can be spread by the airborne route, it’s not likely to be a major route of transmission.

Given what we know, the dilemma is whether to employ the precautionary principle and assume the airborne route plays an important role in disease transmission — and adjust infection control measures accordingly. This may take the form of encouraging wider use of masks and looking at increasing ventilation in enclosed spaces.

The other approach is to wait for more definitive evidence before changing the public health advice.

We will await with interest the WHO’s response to the open letter.




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The Conversation


Hassan Vally, Associate Professor, La Trobe University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

There’s no evidence the new coronavirus spreads through the air – but it’s still possible


Ian M. Mackay, The University of Queensland and Katherine Arden, The University of Queensland

A recent announcement by a Chinese health official suggested the new coronavirus might spread more easily than we thought, via an “airborne route”. The virus is now known as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while the name of the disease it causes is now called COVID-19.

The Chinese Center for Disease Control and Prevention almost immediately corrected the announcement, noting SARS-CoV-2 was not known to be an airborne virus.

The centre confirmed the virus appears to spread via droplets, direct contact and by coming into contact with contaminated surfaces and objects. The World Health Organisation agrees.

So far no infectious virus has been recovered from captured air samples. This would need to occur to demonstrate the virus was airborne.




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What’s the difference between airborne and droplet spread?

When we sneeze, cough or talk, we expel particles in a range of sizes.

The bigger, wet droplets larger than 5-10 millionths of a meter (µm or micrometre) fall to the ground within seconds or land on another surface.

These wet droplets are currently considered to be the highest risk routes for the SARS-CoV-2.

But smaller particles aren’t implicated in the spread of SARS-CoV-2.

Smaller particles remain suspended in the air and evaporate very quickly (at less than one-tenth of a second in dry air). They leave behind gel-like particles made of proteins, salts and other things, including viruses.

These leftovers are called “droplet nuclei” and can be inhaled. They may remain aloft for hours, riding the air currents through a hospital corridor, shopping centre or office block. This is what we mean when we talk about something being airborne.




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But there’s more to airborne spread. To infect humans, the droplet nuclei need to contain infectious virus. The virus must be able to land on our mucous membranes – the soft lining of our ears, nose, conjunctiva (eyelid), throat and digestive tract and it must be able to enter our cells and replicate.

There also needs to be enough virus to overcome our early immune responses to the invader and start an infection.

So a few stars have to align for airborne infection to result.

When we cough, sneeze or talk, we expel particles in a range of sizes.
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But airborne transmission wouldn’t be a shock

We already know the measles virus can remain aloft in a room for up to 30 minutes after an infected person leaves it.

Likewise, the MERS coronavirus has been captured in infectious form from hospital air samples and found to be infectious.

So there is some precedent.

Other viruses that can be infectious via an airborne route include rhinoviruses (the main causes of the common cold) and flu viruses.

The ability for common respiratory viruses to spread via airborne particles means it wouldn’t be a shock to find SARS-CoV-2 also had this capability.

But there is no evidence this is currently occurring.




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Why would airborne spread be such a problem?

Airborne spread would mean the virus could travel further. It could spread through unfiltered air conditioning ducting and reach people further away from the infected person, despite them not being in their direct line of sight.

It would also affect how far away from the patient hard surfaces need cleaning and whether airborne personal protective equipment (PPE) precautions – such as P2 respirator masks – would need to be more widely used.

Our definition of “sufficient contact” for someone to be a possible new infection may broaden, which would mean more people need to be monitored, tested and possibly quarantined for each known patient.

But even if an airborne route is found in the future, it’s unlikely to be the major route of transmission.

People who are ill and show symptoms such as coughing and sneezing usually produce and expel viruses in greater amounts than those who show fewer symptoms. These sicker people are more likely to spread the virus via bigger wet droplets, physical contact and contamination of surfaces and objects.

Do I need to worry?

No. SARS-CoV-2 has been spreading the whole time, regardless of our understanding of how. That spread doesn’t look to be changing.

Currently, relatively few people infected with SARS-CoV-2 are outside of mainland China. Only 15 cases have been identified in Australia. Those found are isolated quickly and are well cared for.




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The chances of catching SARS-CoV-2 outside of mainland China are, at the moment, remote (provided you aren’t on a certain cruise ship).

If the situation changes because infected travellers arrive in greater numbers than we can contain, then our best tools to mitigate spread remain the ones we already know:

  • distancing ourselves from obviously ill people
  • hand-washing
  • cleaning surfaces
  • good cough etiquette (coughing into a tissue or your elbow and washing your hands)
  • keeping our hands away from our face.

And if you are at risk, stay home and seek medical advice by phone.The Conversation

Ian M. Mackay, Adjunct assistant professor, The University of Queensland and Katherine Arden, Virologist, The University of Queensland

This article is republished from The Conversation under a Creative Commons license. Read the original article.