EXPLAINER

Epidemiologist Mary-Louise McLaws explains masks' effectiveness against COVID's Omicron variant

Head pharmacist Andrew Benjamin and assistant Vicki McAndrew of Campbell Pharmacy say mask demand is outstripping supply. Picture: Keegan Carroll
Head pharmacist Andrew Benjamin and assistant Vicki McAndrew of Campbell Pharmacy say mask demand is outstripping supply. Picture: Keegan Carroll

With ever-changing rules and regulations being implemented in response to the COVID pandemic, wearing masks in public is one of the simplest things Australians can do to stay safe.

But with Omicron spreading rapidly, masks are being re-examined.

Last December, the Therapeutic Goods Administration (TGA) said it would conduct a review of the wide variety of masks - many imported after being manufactured overseas - being included in the Australian Register of Therapeutic Goods (ARTG).

While national health authorities have not mandated any new changes, some experts are saying it would be ideal for people to consider upping their protection from cloth masks to surgical and respiratory ones.

What are the differences among the three types?

The TGA says that surgical masks are single-use, disposable masks that act as a physical barrier to prevent transmission of droplets and fluid.

Respiratory masks, with P2/N95 masks being the most common and available at pharmacies and hardware stores, cover the mouth and nose with a tight seal and block up to 95 per cent of particles.

"If worn correctly, they filter the air to prevent the transmission of airborne infectious agents," the TGA says.

Cloth masks can be washed and reused multiple times, and they are sometimes called fabric masks.

"It is recommended that reusable cloth masks are made of three layers of fabric, with a water-resistant outer layer," the TGA says.

They are not regulated and are not recommended in medical settings.

Surgical masks are disposable, and act as a physical barrier to prevent transmission of droplets and fluid.

They are graded as level 1, 2 and 3, with higher levels indicating a higher degree of protection.

The types of face protection. Source: TGA

The types of face protection. Source: TGA

How well do cloth masks work at preventing the spread of COVID?

University of NSW epidemiologist Mary-Louise McLaws, who is also a member of the World Health Organisation's Infection Prevention and Control group for COVID, says cloth masks definitely need three layers and need to follow WHO requirements to be most effective. The triple layers prevent people from breathing the virus in or out.

How can you know if your cloth mask is up to standard?

If you are buying cloth masks from a provider, you need evidence they are made according to WHO guidelines, including the three layers.

Professor McLaws says the middle layer of the three-layer standard is supposed to be like the inner layer of a medical mask, which is charged with static electricity.

"If it is a three-layered mask, one of the ways of getting that inner layer to be charged to prevent a particle from coming through that middle layer is to gently rub the mask between your fingers. That should increase the charge of the middle layer," she says.

If there is only one layer, that single-layer cloth mask can get wet quickly, and once it is wet then anything can get through easily.

Are surgical or respiratory masks better than cloth against Omicron?

Professor McLaws says respiratory masks are worn mainly by healthcare workers, usually with a face shield, to protect themselves from airborne spread during "aerosol-generating procedures".

Those procedures, such as intubating a patient, cause virus particles to become smaller and stay in the air for longer.

"[Health workers] are well protected and they don't need to wear an N95/P2 mask when they perform routine healthcare," she says.

"Without performing an aerosol-generating procedure, they are not going to get a face full of virus."

MORE COVID NEWS:

Professor McLaws says people are not required to wear respiratory masks in the community, but also says no harm would be done by people wearing one - other than some discomfort if it's for a long period of time.

"If people want to wear a P2 or an N95, they can buy them. A hospital P2 mask is even better, but it is hard to wear all day long," she says.

Professor McLaws suggests a three-layered cloth or surgical mask, at a minimum, both indoors and outdoors.

Elsewhere, CNN medical analyst Dr Leana Wen, an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health, recently said there was "no place" for cloth masks in light of Omicron.

"We need to be wearing at least a three-ply surgical mask," she said.

Dr Wen said that in crowded places, people "should be wearing a KN95 or N95 mask".

Why is Omicron more transmissible?

Professor McLaws says both the Delta and Omicron variants live in the air, and can put people at risk of airborne spread, rather than just droplet spread.

"Droplet transmission is when the virus comes out of your mouth and is heavy, more than five microns, like dwelling in saliva for example - so a droplet drops to the floor very, very quickly," she said.

"With Omicron, it's not scientifically tested yet, but there's a suggestion by some of the physicists in America that [the] Omicron spike has the ability to be charged - negative and positive charges - which then allows that saliva or lung fluid to surround the virus.

"[It's] still lighter weight, but this stops the virus from drying out fast.

"It can stay in the air indoors for a much longer time, so that you can be at risk of airborne spread."

Experts say the N95 respiratory mask is more effective against Omicron. Picture: Shutterstock

Experts say the N95 respiratory mask is more effective against Omicron. Picture: Shutterstock

The Australian Health Protection Principal Committee recently reiterated the importance of masks in suppressing COVID.

"Wearing a mask is not dependent on whether an individual is vaccinated or mandated by public health orders," it said.

The federal government's Infection Control Expert Group, which has a guidance webpage, said "a mask or respirator is not a substitute for other precautions which must be used to prevent spread of COVID".

What else can people do to protect themselves?

Professor McLaws says people should also look after their eyes.

"We should wear glasses, sunglasses or anything to protect our eyes, because they have what is called ACE2 receptor sites [entry points for the virus]," she said.

"If you're indoors and somebody has breathed out through their nose because they're not wearing their mask over their nose or not wearing a mask over their mouth then it could get into your eyes."

This story Are our face masks up to scratch against Omicron's rapid spread? first appeared on The Canberra Times.