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I've read all the papers cited by Govt evidence report regarding face coverings.
First of all, I was astounded at the amount of refeneces to newspaper articles & YouTube videos of various officials & journalists saying masks should be mandatory..
Thread: https://www.gov.uk/government/publications/delve-report-on-face-masks-for-the-general-public-21-april-2020
First of all, I was astounded at the amount of refeneces to newspaper articles & YouTube videos of various officials & journalists saying masks should be mandatory..
Thread: https://www.gov.uk/government/publications/delve-report-on-face-masks-for-the-general-public-21-april-2020
There is also much discussion about studies on face masks & coverings for controlling influenza, which is naturally a very different virus to #COVID19. Apart from simply pointing this out, the report doesn't adequately discuss why this is problematic...
The only study reported about droplet/aerosol reduction by use of masks, specific to coronaviruses, showed only some effectiveness of *medical* masks (not fabric coverings). Moreover, this study was on symptomatic individuals, who presumably on the whole aren't out shopping...
"One study showed some evidence that wearing cloth masks could increase viral infection rates. However, the result was not replicated in a different (very extended wear of PPE for hospital staff in Vietnam)"
Note this is the only place where replication problems are mentioned...
Note this is the only place where replication problems are mentioned...
Here's the paper: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/
"Virtually all studies on mask usage are focused on their use for the protection of the wearer... Such studies are irrelevant to the question of whether mask use will provide source control. To our knowledge, only 2 studies have been performed that studied the effectiveness of...
"... mask use by the source patient with a viral respiratory infection (mostly influenza), tracking the
development of symptoms in others. Both studies used medical masks and monitored transmission to household members. Both have flaws, [including low] sample sizes..."
development of symptoms in others. Both studies used medical masks and monitored transmission to household members. Both have flaws, [including low] sample sizes..."
"(A Telegraph) survey of 1,500 Britons found that 41% believed that the public should be asked to wear masks, compared to 33% who disagreed, so there is already public support for this"
I'm not sure how this conclusion can be drawn from these percentages...
I'm not sure how this conclusion can be drawn from these percentages...
The report also draws broad comparisons between growth in cases in mostly south east Asian countries (where mask use is more common) and European countries (where it was not), heavily implying a role of mask wearing with very minimal discussion of other significant factors...
In terms of the papers, here are a few:
"... most studies reported about use of medical grade (surgical paper masks). In 3 RCTs, wearing a facemask may very slightly reduce the odds of developing ILI/respiratory symptoms" https://www.medrxiv.org/content/10.1101/2020.04.01.20049528v1
"... most studies reported about use of medical grade (surgical paper masks). In 3 RCTs, wearing a facemask may very slightly reduce the odds of developing ILI/respiratory symptoms" https://www.medrxiv.org/content/10.1101/2020.04.01.20049528v1
"Surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols... surgical face masks could prevent transmission... from symptomatic individuals" https://www.nature.com/articles/s41591-020-0843-2
There are a couple more, which you can see via link in the first tweet. But essentially, little to no high quality scientific evidence is presented for the effectiveness of fabric coverings. The studies are primarily on medical grade masks and based on symptomatic transmission...
... In line with @carlheneghan, see https://twitter.com/jadenozzz/status/1294996361130188800?s=19
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