[RobertG (OP)]

What's the current opinion on masks? I seem to remember Chris on TV saying that most were of fairly useless.
It seems to me that the sudden surge of advice from the Gov't and WHO are kneejerk reactions to media pressure.
What bothers me about masks is that people with them seem to think they're not vulnerable and are very careless about distancing.

[alancalverd]

A simple, loose-fitting surgical mask won't do much to prevent you becoming infected as it doesn't filter incoming air very effectively. That was never their purpose, which is primarily to prevent clinical staff from infecting patients.

It will of course slow down and catch some of your exhaled aerosol and reduce the likelihood of you infecting others, which is  why any mask is important in a COVID epidemic as you may unknowingly be infectious but asymptomatic.

A fully-fitting HEPA mask will reduce the likelihood of inhaling droplets from other people, and thus go some way to protecting the wearer from becoming infected. In this respect, a builder's dust mask, though not intended for medical use, is probably more effective than a surgical mask. Builders' goggles are also effective against sneezed droplets.

Reducing probability is not the same as conferring invulnerability (wave a bible) or eliminating the risk (quarantine).   

[set fair]

The metastudy from the Lancet found face masks reduced transmission by 80%. Hardly surprising. 10 years from now pschologists will be writing books trying to figure out why, otherwise sane and educated people kept coming up with so many bizare reasons why they wouldn't slow spread.

Keep your distance
Wash your hands
Wear a mask
Take your vitamin D

[Bored chemist]

The metastudy from the Lancet found face masks reduced transmission by 80%.

What sort of masks?

N AV mask.png (202.02 kB . 323x347 - viewed 2614 times)

[alancalverd]

Aha! The Cummings-Johnson design: glittery, with a hole in the middle.   

[Edwina Lee]

The metastudy from the Lancet found face masks reduced transmission by 80%. Hardly surprising. 10 years from now pschologists will be writing books trying to figure out why, otherwise sane and educated people kept coming up with so many bizare reasons why they wouldn't slow spread.

Keep your distance
Wash your hands
Wear a mask
Take your vitamin D

Perhaps it is the psychological phenomena of the 5 stages of grief - Kubler-Ross model
https://en.wikipedia.org/wiki/K%C3%BCbler-Ross_model

[Edwina Lee]

Confirmation of the effectiveness of face masks to prevent the spread of covid-19:-

https://www.pnas.org/content/117/26/14857

The definitive evidence in asingle graph:-
https://www.pnas.org/content/pnas/117/26/14857/F3.large.jpg?width=800&height=600&carousel=1