Thread by @DellAnnaLuca

A REVIEW OF BAD ARGUMENTS AGAINST FACE MASKS

1/ They don't fully protect you from virus in the air.

Yes, but their point is to prevent as much virus as possible from getting in the air in the first place.

(thread)

2/ There is this Randomized Control Trial I see posted on Twitter which allegedly shows that face masks do not work.

That trial shows that face masks do not protect doctors from patients *that do not wear face masks*.

Such studies do not demonstrate that face masks don't work.

3/ Paradoxically, the more you believe that someone wearing face masks is only partially protected, the more you should want everyone to wear them, so that there is less virus in the air.

That's how real herd immunity works.

4/ Second bad argument: countries using masks are still hit by a second wave, so they do not work.

By that reasoning, brakes do not work because all cars have them and crashes still occur.

Face masks might not be sufficient, but this does not imply that they're not useful.

5/ Third bad argument: people don't wear them properly.

As long as people wear them above the nose, they prevent sneezes from reaching people 1m away.
That alone would justify wearing them.

And even just on the mouth they reduce the reach of cough.

6/ Fourth bad argument: masks are hazards because people touch them while taking them off and get contaminated.

Perhaps, but the virus that landed on the face mask would have landed on the nose or mouth, if the mask hadn't been there. Hardly a better outcome.

7/ Moreover, the same applies to glasses 🤓 and phones.

But I never heard anyone saying that people shouldn't use glasses because they are a contamination hazard.

(BTW, people, please consider washing glasses and phones when you get back home from outside)

8/ Fifth bad argument: face-mask compliance cannot realistically reach 100%.

It does in some Asian countries, so it could.

But even assuming it cannot in the Western World, that doesn't imply that we shouldn't recommend them or even mandate them.

9/ Again: the more you believe that some people won't or cannot wear them, the more you should insist for everyone else to wear them.

That's how real herd immunity works: those who cannot or won't get vaccinated are protected by those who can and do.

10/ Sixth bad argument: masks cause CO2 build-ups.

They probably do, but minimally and over long-term use only. I do not think that this is a significant health hazard for most people – otherwise how could doctors and other professionals wear them for full shifts for decades?

11/ Even if wearing face-masks did have a small negative health effect, this by no means implies that their net effect is negative.

Catching and spreading the virus has far worse negative effects.

12/ Seventh bad argument: no randomized control trial showed that masks work.

This is a terrible argument for two reasons

The first one is that the costs of wearing face-masks is low and bounded, whereas the costs of not wearing them is high and unbounded (the pandemic growing)

13/ This means that the burden of the proof should be on those who are against face masks, and that they should prove that their negative effects are larger than their positive ones.

This is tricky though, for the former are constant whereas the latter are fat-tailed.

14/ The second reason is that such an RCT should not only involve participants wearing masks, but it should ensure that they only interact with people wearing masks, and that they do so in a real-world setting (i.e. no lab) AND that they do so in a virally-charged environment.

15/ Good luck satisfying all 4 conditions at the same time.

Any study that doesn't cannot claim that it proved that masks aren't effective in the real world.

16/ Why did I say that the RCT has to take place in a real-world setting?

Because in real life, you meet tons of people a few minutes at a time (e.g. in the bus, at the grocer, etc).

This is completely different from a hospital where you meet the same few people for days.

17/ If masks are partially but not fully effective, they would work great in the first scenario (real-life) but terribly in the second one (lab).

Hence why I'm skeptical of "face-masks do not work" studies made in labs.

18/ Eight bad argument: my friend always wears face-masks and yet he got sick.

Yes, I also know someone who drives carefully and got hit by a reckless driver.

Your friend probably got sick because someone else wasn't wearing face-masks. (or he got it at the restaurant, etc.)

19/ A clarification. In tweet #10, when I said “they probably do”, I misspoke. I was thinking about “even if they do”.

I’ve seen no evidence that they do.