Modern Australian

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

  • Written by Ian M. Mackay, Adjunct assistant professor, 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.

Read more: How does the Wuhan coronavirus cause severe illness?

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.

Read more: We're in danger of drowning in a coronavirus 'infodemic'. Here's how we can cut through the noise

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.

There's no evidence the new coronavirus spreads through the air – but it's still possible When we cough, sneeze or talk, we expel particles in a range of sizes. Shutterstock

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.

Read more: Coronavirus: how worried should I be about the shortage of face masks? Or can I just use a scarf?

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.

There's no evidence the new coronavirus spreads through the air – but it's still possible If we find out the new coronavirus spreads through the air, this might change the way we protect ourselves. Jeon Heon-Kyun/EPA

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.

Read more: How contagious is the Wuhan coronavirus and can you spread it before symptoms start?

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.

Authors: Ian M. Mackay, Adjunct assistant professor, The University of Queensland

Read more https://theconversation.com/theres-no-evidence-the-new-coronavirus-spreads-through-the-air-but-its-still-possible-131653

NEWS

it's a proven way to reduce emissions but everyone's too scared to mention it

Opposition leader Anthony Albanese sought to claim the climate policy high ground last week with his commitment to a net-zero emissions target by 2050. But figures on Australia’s emissions from...

cashless welfare cards do more harm than good

ShutterstockThe Australian government touts compulsory income management as a way to stop welfare payments being spent on alcohol, drugs or gambling. The Howard government introduced the BasicsCard more than a...

women in mental health wards need better protection from sexual assault

ShutterstockMental health inpatient units should be safe and healing places. But we’ve found women staying in these units are being threatened, harassed and sexually and physically assaulted by men.These are...

Stone tools show humans in India survived the cataclysmic Toba eruption 74,000 years ago

Christina Neudorf, Author providedAbout 74,000 years ago a volcanic eruption at what is now Lake Toba in Sumatra, Indonesia, created one of the most dramatic natural disasters of the past...

Five Australian universities get the bulk of philanthropic donations

Wes Mountain/The Conversation, CC BY-NDPhilanthropy is a growing source of revenue for Australian universities. It’s essential to advancing quality research, equity and learning. On average, Australia’s top five fundraising universities...

Retirement Income Review can't ignore the changing role of home

natasaelena/ShutterstockThe assumption that retired people have minimal housing costs underpins the settings of our retirement incomes system. But the real state of housing for older Australians today makes it critical...

The jobs market is nowhere near as good as you've heard, and it's changing us

We are continually being told that more of us are employed than ever before. Reserve Bank Governor Philip Lowe points out (correctly) that a higher proportion of us are in...

the film that inspired Virginia Woolf, David Bowie and Tim Burton

Decla-Bioscop AGBerlin. February 26 1920. A new silent film, The Cabinet of Dr. Caligari, is released to unsuspecting German audiences and quickly becomes a worldwide sensation. “When will I...

Inquiry probing 55 matters relating to special forces' alleged misconduct in Afghanistan

The inquiry into allegations of misconduct by Australian special forces in Afghanistan is examining 55 separate incidents or issues, according to the Inspector-General of the Australian Defence Force report, tabled...

If you're ageing and on medication, it might be time to re-assess your alcohol intake

ShutterstockDrinking patterns tend to change as we age. The older we get, the more likely we are to drink on a daily basis. But older adults often perceive that drinking...

Government backs Labor call for Bettina Arndt to lose Order of Australia award

The Coalition government has supported Labor’s motion in the Senate to call for men’s rights activist Bettina Arndt to be stripped of her Order of Australia award over her comments...

Weinstein conviction a partial victory for #MeToo, but must not overshadow work still to be done

Hollywood producer Harvey Weinstein (centre) has been convicted of rape in the third degree and a criminal sex act in the first degree.AAP/EPA/Justin LaneThe downfall of disgraced Hollywood producer Harvey...

Popular articles from Modern Australian

Effective Ways to Improve the Value of Your HomeThe Complete Routine to Burn Fat and Build Muscle Tips to get softer skinFive things to do when visiting London5 ways to make your hair shiny through dietHow to stick to your resolutions all-year-roundDebunking Common Physiotherapy MythsWhat drives the growth of online betting in 2020?8 Ways CBD Is Influencing the Coffee IndustryHow to Play Baccarat Like an Expert: A Beginner’s GuideSURPRISE YOUR KID WITH DREAM TOYTIPS FOR BRIDE ON THE EXPO EVEThe Ultimate Annual Home Maintenance GuideWHY SHOULD YOU GIVE UP SUGAR?