Originally Posted by nffc

What he said is still right though, with important caveats.


"there is no evidence to suggest that wearing cloth face masks amongst people who are well reduces the spread of the virus"


Key point is the bold. Most people who understand what benefit they (do/may) have know that the point is to reduce the viral load emitted from someone who has the virus.


Someone who doesn't have the virus doesn't have any viral load to reduce, so there is no benefit or spread reduction from them wearing the mask.



Someone who is well, in general, is unlikely to have the virus - and that is the key caveat, since we know (and have since the early days from Italy) that people can test positive for the virus without having symptoms, and you would class those as being well. So the key point there would depend on the viral load of someone who has covid-19 without any symptoms and how much this would be transmitted by them having no symptoms (e.g. if they breathe or vocalise) as opposed to how much is transmitted if they cough, sneeze etc.



Whitty and Van Tam are consultant professors of virology, and especially the latter who is of Far East origin, would both presumably be aware of the mask-wearing culture which is more obvious there. They wouldn't be wrong, and still aren't. Also what Jenny Harries said about them causing potentially more harm than good is still true with people reusing masks, touching them, putting them round their chins, taking them off and not putting them somewhere clean, all of this can still cause infection in yourself and in others.


The issue with masks is a mechanical one though. If the gaps between your mask fibres are more of the same magnitude as the particles you're trying to stop, they have more chance of doing so. A weak mask will of course stop the largest droplets but the smallest ones and the aerosols as well as "naked" virus will still pass easily. I guess it depends how effective this needs to be.