Trish Greenhalgh
A
1. Thread on masks (also posted on Twitter). Addresses:
- Why so much controversy?
- Airborne transmission
- RCTs of masks – strengths/limitations, community, healthcare settings
- Meta-analyses – gold standard or lazy lumping?
- Non-RCT evidence – why is it needed, what does it show?
- AOB
09:16 AM - Feb 26, 2023
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Trish Greenhalgh
A
In response to Trish Greenhalgh.
2. Before I start, here’s my OLD mask thread from Twitter July 21, which ran to >100 tweets. Some of that is now rather dated but a lot still holds. I’ll paste the best from that into this new thread. Will take a while (~100 total)
https://twitter.com/trishg...
09:17 AM - Feb 26, 2023
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Trish Greenhalgh
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In response to Trish Greenhalgh.
3. WHY IS MASKING SO CONTROVERSIAL?
First, ‘masks’ and ‘masking’ are very broad terms. They cover different technologies (cloth, medical, respirator), wearers (public, patient, healthcare worker), settings (low v high risk) and requirements (mandated v free choice).
09:18 AM - Feb 26, 2023
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Trish Greenhalgh
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4. WHY CONTROVERSIAL?
Because of this multiplicity, statements like “masks [don’t] work” may be referring to very different interventions in different populations for different activities at different times, not to mention different diseases. The literature, in short, is a mess.
In response to Trish Greenhalgh.
09:18 AM - Feb 26, 2023
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Trish Greenhalgh
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In response to Trish Greenhalgh.
5. WHY CONTROVERSIAL?
Second, masking is a cultural practice as well as a public health intervention. It has symbolic meaning. Pirates and burglars wear masks. To some, masking means you’re a ‘pansy’, ‘sheep’ etc. Masking offends libertarians.
https://www.bmj.com/conten...
09:19 AM - Feb 26, 2023
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Trish Greenhalgh
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In response to Trish Greenhalgh.
6. WHY CONTROVERSIAL?
There’s strong social pressure to mask in some settings to contribute to the greater good (“my mask protects you”). People may feel pushed into doing something which a) feels awkward, b) symbolises an allegiance they don’t identify with and c) they feel is ineffective.
09:20 AM - Feb 26, 2023
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