Should I wear a face shield for added protection against coronavirus? - ABC News

If you're in Melbourne, and you're considering donning a face shield along with a mask for added protection against coronavirus, you're in good company — the Professor of Infectious Diseases at ANU Medical School would do the same.

If they're good enough for the medical professionals, like the woman in the photo above, why not for you too, right?

However, a word of warning: the Professor of Global Biosecurity at UNSW says face shields are not that useful for preventing an infection that can be spread through aerosols — and coronavirus fits that bill.

So, let's see what they both had to say.

For the latest news on the COVID-19 pandemic read our coronavirus updates story.

One expert told us he can't see how they'd hurt — and he can see how they'd help

Professor Peter Collignon from ANU Medical School endorsed face shields when he appeared at the Senate Select Committee on COVID-19 in June and he still thinks they're a great idea.

"If I was in Melbourne, I would be wearing a cloth or a surgical mask, but I would wear a face shield as well until the numbers come down," he said.

In fact, he says he's already used a face shield — for instance, on a visit to the hardware store as well as when working in his Canberra laboratory.

As well, he's bought them for family members in case the situation deteriorates.

However, he also points out that he's based in the ACT, where there hasn't been community transmission of coronavirus in months.

"This isn't an absolute rule. I think what you do has to be proportionate to what the risk is in the community, which will change from time to time," he said.

He says there are several benefits to face shields

These are the benefits Professor Collignon listed:

• They provide protection not just for the wearer's nose and mouth, but for their eyes, which Professor Collignon says are another way for viruses to get into your system
• They also provide protection for people other than the wearer, by limiting the spread of their droplets
• They decrease the chances of the wearer touching their face
• If masks aren't being worn properly, face shields offer another layer of protection
• For people who can't wear masks, face shields provide a level of protection that's "better than nothing"

Professor Collignon says face shields are basically portable perspex screens

People around the world have already decided to start wearing face shields.(AP: Achmad Ibrahim)

He compared them to the screens that have been installed in front of cashiers at the supermarket.

"If we don't think these are a good idea, why do we think it's a good idea to do it at Woolworths and Coles?" he said.

As far as he is concerned, the decision-making about wearing masks and face shields should be the same.

"Whenever it's a good idea to wear a face mask, I think it's probably a good idea to think about wearing a face shield," he said.

However, Professor Collignon acknowledges there's "not good evidence" on the effectiveness of face shields for preventing the transmission of coronavirus.

"There's some evidence, but it's not great. There's a lot of these things we haven't done enough studies on and we need to do the studies," he said.

Not just any piece of plastic in front of your face will do

Face shields that can be bought at hardware stores are much the same as those worn by health professionals.(Bunnings)

Professor Collignon says face shields aren't difficult to produce in large numbers — in fact, people can even make their own.

However, there are minimum requirements.

"They've got to be well below your chin and they've got to wrap around your face. They've got to be a reasonable size," he said.

Professor Collignon says face shields also need to be regularly washed, they can't be shared and they don't replace other protective measures including washing hands and keeping distance from others when possible.

But there is a significant limitation with face shields — aerosol transmission

There is growing evidence that small droplet (airborne) transmission is a significant route of infection indoors.(Supplied: Airborne transmission of SARS-CoV-2 By Lidia Morawska)

The significance of droplet transmission of coronavirus, as Professor Collignon explains it, is that the droplets that infected people emit can travel a small distance, but ultimately "drop" (hence the name).

Coronavirus can also spread through aerosol transmission, however, which Professor Collignon says involves "infectious particles" that are in the air for hours.

In July, the World Health Organization changed its advice around how coronavirus spreads; whereas previously it maintained that droplets were the number one enemy, it now acknowledged the risk of aerosol transmission.

Raina MacIntyre, the Professor of Global Biosecurity at UNSW and the head of the Kirby Institute's Biosecurity Research Program, says the scientific evidence suggests that aerosols are "a significant mode of transmission".

That's a problem because air can flow freely through the bottom and sides of face shields.

"If you are ill, your respiratory aerosols will travel out and infect others; if you are well, you will be breathing unfiltered, contaminated air," she said.

So, Professor MacIntyre says you still need to wear a mask

She says face shields are useful when worn over a mask, but not as a substitute.

"For people who cannot wear a mask (such as those with a disability or breathing problems), they can be used, but it is better to minimise situations of risk, because you can get infected using a face shield," Professor MacIntyre said.

She pointed to a situation in Switzerland, where hotel staff could choose to wear a mask or a shield, and only staff wearing shields got infected.

She also cited one study that put this in stark — and, to be honest, disgusting — context

Professor MacIntyre pointed out that the scientific journal Physics of Fluids had published a study on "virus transmission from urinals" last month.

The upshot?

"If you are wearing a face shield at the urinal you will be inhaling other people's urine," Professor MacIntyre said.

Cool, cool.

For what it's worth, that study concluded that "wearing masks should be made mandatory in public washrooms".

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2020-09-05 20:06:00Z
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