Much has been made of WHO’s change of mind on the use of masks in June, which is said by many to have been a game-changer. However, the relevant WHO document, ‘Advice on the use of masks in the context of COVID-19 Interim guidance’, is anything but decisive.
It says (on p. 6):
There is limited evidence that wearing a medical mask by healthy individuals in households, in particular those who share a house with a sick person, or among attendees of mass gatherings may be beneficial as a measure preventing transmission… Results from cluster randomized controlled trials on the use of masks among young adults living in university residences in the United States of America indicate that face masks may reduce the rate of influenza-like illness, but showed no impact on risk of laboratory-confirmed influenza. At present, there is no direct evidence (from studies on COVID-19 and in healthy people in the community) on the effectiveness of universal masking of healthy people in the community to prevent infection with respiratory viruses, including COVID-19.
(Note that the document doesn’t spend any time going through the studies, it’s simply a summary document.)
The document concludes (p. 6):
At the present time, the widespread use of masks by healthy people in the community setting is not yet supported by high quality or direct scientific evidence.
Despite all this, WHO still recommended that governments encourage mask-wearing. What was their justification for doing so? It says this (p. 6, my brackets):
taking into account  the available studies evaluating pre- and asymptomatic transmission,  a growing compendium of observational evidence on the use of masks by the general public in several countries,  individual values and preferences, as well as  the difficulty of physical distancing in many contexts, WHO has updated its guidance to advise that to prevent COVID-19 transmission effectively in areas of community transmission, governments should encourage the general public to wear masks in specific situations and settings as part of a comprehensive approach to suppress SARS-CoV-2 transmission.
This paragraph doesn’t provide any further reason for pushing masks. Nothing is said about the relevance of “available studies evaluating pre- and asymptomatic transmission”. And if the evidence for face masks stopping virus spread is weak in general then that’s going to apply to the early stages of a disease as well.
As for the “growing compendium of observational evidence on the use of masks by the general public in several countries”, this is a scientifically useless statement. What observational evidence? How do any such observations show that wearing a face mask is effective against Covid? How is this observations measured? It is incredible to think that the whole world is being changed on the basis of such evasive language.
 adds nothing of use. It seems to mean they took into account “individual values and preferences” when coming to their decision. It is entirely unclear how they did so, seeing as most people preferred not to wear a mask when they had the choice, but anyway this vague and irrelevant statement provides no extra reasons to mandate mask wearing.
 also doesn’t provide (nor, I think, is it intended to provide) an independent reason for mandating masks, as it is already assuming that masks have some effect.
So we do not have any additional justifications from this paragraph. (Note also the phrase “as part of a comprehensive approach” – this reads like an admission that you can’t rely on masks to do much on their own.)
My conclusion, then, is that WHO is pushing masks despite admitting that the evidence for them is poor. It is incredible to think that a fundamental change in human history, with healthy human beings forced by governments around the world to wear face masks for a mild disease that is dying away, has been brought in on the basis of a document that admits that there isn’t any good scientific evidence to justify this change. (You have to wonder how many of the people who have made policy based on this document have actually read it.)
One is very tempted to think that the stories about WHO changing their advice in response to political pressure are true, because WHO fails to provide any scientific grounds for their position.
It should also be noted that WHO warned of potential disadvantages of mask-wearing, including the following:
– potential increased risk of self-contamination due to the manipulation of a face mask and subsequently touching eyes with contaminated hands;
– potential self-contamination that can occur if non-medical masks are not changed when wet or soiled. This can create favourable conditions for microorganism to amplify;
– potential headache and/or breathing difficulties, depending on type of mask used;
– potential development of facial skin lesions, irritant dermatitis or worsening acne, when used frequently for long hours
One further thing needs to be said. Nowhere in this document did WHO recommend that governments force their citizens to wear masks through means of law enforcement. It merely says that governments should encourage their use, and furthermore, merely as part of an overall approach. Many governments, including the British government, have gone far beyond what WHO have recommended.
From the BBC just after the WHO document came out:
“Masks on their own will not protect you from Covid-19,” Dr Tedros said.