How often does a face mask stop a virus?

[Goonshow]

I'm curious about this. It now appears to be widely accepted that a face mask helps stop a virus spreading. But how often does a single mask do the job and save a single infection?

I think it happens rarely. I don't think masks stop the virus much, if at all, and I find the blind acceptance that they do puzzling.

My initial guess is that a mask worn by someone each day will stop transmission of the virus less than once a year.

Anyone else care to give their thoughts?

People saying we can't calculate it I've suggested, how am I wrong?

I'm not talking about the efficacy of the mask versus the virus in a single encounter; I'm asking how many times has the mask won in total?

You can calculate that in the way I have suggested, surely? If not, why not?

@OverTheRainbow88

Offering a guess is totally pointless and probably a bit dangerous.

What’s the point?

Agreed! I’m an epidemiologist (not infectious disease) and such a question would take a team of my v smart colleagues, modelling software and at least a couple of weeks of consideration and debate to come up with a range of plausible answers

You seem to have an agenda... what is it?

@lunapeace

Apparently the whole worlds Covid particles would fit in half a coke can. Therefore, I truly believe most masks are useless (certainly the cloth or make your own adopted here).

You do realise they don't float around of their own accord? They are carried in saliva, respite droplets. Masks only have to protect from the droplets.

@ArseInTheCoOpWindow

Double masks worn tightly prevent 95% of infection according to Dr Faucci. Who is the top bod in USA l think

And probably prevent 95% of breathing as well.

@AntiHop

If masks don't work, why do surgeons and dentists wear them?

The ones in hospitals work.

My friends dad is a prison officer who often has to fo bed watch, meaning escorting prisoners to hospital etc. He was not allowed on a ward with his face mask on, the doctor told him "they're as much use a chocolate fire guard" and handed him one of their own.

Surely a mask prevents the spread of the virus in the same way coughing or sneezing into a tissue prevents the spread of colds and flu?

What on earth makes you think your “initial guess” is as valid as multiple scientific studies? You’ve a fair conceit of yourself OP.

@OverTheRainbow88

You seem to have an agenda... what is it?

It appears to have been accepted by the majority that masks stop the virus. My feeling is that they don't, but my next question is how many times do they stop the virus?

I think that question is a reasonable one.

The very crude modelling I have done can't get any accurate answers of course, but I suggest that it can rule some things out.

For example, does anyone believe, after giving it 5 minutes' thought, that your own mask is stopping the virus every week?

@Goonshow

As I’ve said upthread, it a) isn’t binary b) Is too complex to attempt the way you’re doing it

Masks reduce the amount of vital particles expelled. This may not always stop transmission but will reduce severity of disease for the people affected. On a population level, this a is a significant benefit for a low risk, low cost and low burden intervention.

*viral

It appears to have been accepted by the majority that masks stop the virus. My feeling is that they don't, but my next question is how many times do they stop the virus?

You don't seem to understand the difference between stop/eliminate and reduce risk @Goonshow

@tommika Surely that’s only for men? If I wet myself it’s probs just gonna go down my own legs.

Call the WHO!
Random Mumsnetter thinks masks don't work.
All those scientists, surgeons etc been so gullible all these years eh?

No agenda my arse.

OP, a close relative was recently hospitalised with Covid. Had only popped to supermarket once or twice in the weeks beforehand, wore a mask every time. Shows how much use they are.

My mask hasn’t stopped me spreading the virus because I’ve not had the virus (at least I got a negative antibody test and I’ve never had symptoms).
Just like my seatbelt has never saved my life because I’ve never had a mid to high speed crash.

But one day I might get symptoms and a positive test and if so I’ll be glad I was wearing a mask in the two days before symptoms which is when you are infectious.

It appears to have been accepted by the majority that masks stop the virus.

I disagree. I think it has been accepted by the majority that masks provide some protection, that by wearing a mask one protects others, and that if one catches the virus but with a lower viral load, that is preferable to catching it with a higher viral load. Therefore by reducing the amount of respiratory droplets flying around, masks provide a degree of protection that is worthwhile.

I don’t think anyone believes a piece of cloth over their face ‘stops the virus’.

What are your statistical credentials?

You're talking nonsense

Of course this thread is going to attract the anti-mask brigade.

No doubt some masks are better than others. But any mask is better than nothing.

All I can say is that schools in France have been back full time, 30 kids and a teacher to a classroom, all wearing masks since September and we’ve had nothing like the disruption in the U.K. before schools closed. DS 13 hasn’t had to isolate once (except when I got Covid and he was cas contact). He’s had one teacher absent with Covid (out of 11) in that time. DS 9 yea - sane in primary. Don’t think he’s had any classmates off, his teachers haven’t been absent at all. DH is a teacher (secondary), he’s not been cas contact or infected through school. And absences of kids has been very minimal. He and I both work in a big big secondary (over 2000 students) and in terms of absences, very very few. No classes closed, not even a suggestion that the school might close.
The classes aren’t miraculously bigger, they aren’t any better ventilated etc - but everyone wears a mask all the time: no exceptions.

@ShouldHaveCouldHaveWouldHave

OP, a close relative was recently hospitalised with Covid. Had only popped to supermarket once or twice in the weeks beforehand, wore a mask every time. Shows how much use they are.

Wishing a speedy recovery to your relative.

However, that does not mean masha don't work. It means that mask didn't work on that occasion. Presumably other people weren't wearing masks. If your relative was wearing a mask when they were infectious, and therefore reduced the risk to other people. And by wearing a mask, they reduced their viral load.

Isn’t that like saying that most antenatal tests are pointless because they are done on healthy foetuses?
You don’t know when the mask is needed, so you use it all the time.
Guess what, most of the time you wouldn’t need to be 2 m away from someone. But there’s no way of telling which times.
Most people could have safely spent Christmas with their extended families, because they weren’t infectious, but there was no simple way of simultaneously ascertaining which people were safe and which weren’t.
I think you haven’t quite understood the point of the measures.

I did get sent this the other day

@antihop thank you.
He said everyone else was wearing one (it was Waitrose after all! ) Or more, he didn’t see anyone else not wearing one.
Didn’t show symptoms till a week or so after the last supermarket trip and hadn’t been out since that trip so hopefully didn’t pass it on to anyone else.
I have definitely noticed though that social distancing has mainly been abandoned since masks were made compulsory, people seem to think they are now magically protected by a metaphorical pratonus.

Dr Jennie Harries on masks before we all lost our minds

Also the infamous Danish study that one must not talk about looking directly at masks in this pandemic....pretty pointless!

www.bmj.com/content/371/bmj.m4586/rr-6