Alright, I'm seeing this paper quoted a lot about the harms potentially caused by masks, so here we go, yes wearing a cloth mask as protection when you're working in a high exposure environment like a hospital is a bad idea.

But it's not as simple as that (1/ https://twitter.com/AlexBerenson/status/1280966807956992002

This trial aimed to see whether the use of simple cloth masks, in resource limited settings, is as effective as "medical masks", that is a three layer non woven mask (surgical mask), in a hospital. 2/

The authors chose high exposure areas, in order presumably to best assess the level or risk. This I
included A&E, ICU, ID, and Respiratory wards.

This is important as many of these can be considered "Red Zones", areas where high risk procedures generating aerosol are done 3/

Also of importance, their control arm also involved mask wearing, in other words whilst the intervention subjects wore masks for >70% of their shift, the control group was also wearing masks possibly for high risk procedures. 4/

Their conclusion, cloth masks gathered more pathogens than medical masks, and more respiratory illnesses occurred.

But of course that's not the end of the story 5/

Cloth masks are generally made of one to two layers of fabric. But they are not designed to keep out droplets or external pathogens in a high exposure environment, it's like wearing water wings to cross the channel. It's not the right tool for the job 6/

What the authors have shown is that in high exposure environment, where you are likely to be exposed to aerosols like in ICU, a cloth mask is of no use and in fact will trap pathogens.

The same does not apply when you are here 7/

On a normal day, no one is being intubated in Lidl.

In a lower exposure environment, a mask serves the simple purpose of preventing droplets spreading out when you speak, or cough.

It should not replace keeping as much distance as you can, and hand hygiene. 8/

"But then shouldn't we all wear surgical masks or FFP3?"

Good point, but the level of protection would be disproportionate to the risk, and exhaust valuable limited supplies of PPE.

You wouldn't dress like this to ride a bicycle to the shops, or like this for a Nerf fight? 9/

Cloth masks/face covering are the best measures to reduce the spread of droplets from an asymptomatic individual, if we do not want to return to the lockdowns of April, or more draconian measures.

In conclusion, if you're working in ICU or A&E, wear appropriate PPE 10/

If you're going to Aldi, Waitrose, or your local furniture shop, wear the goddamn cloth face covering.

~fin~