A very unfortunate, badly run meta analysis as I understand it which fundamentally undermined trust in their governance because it was so easily critiqued. I haven't seen a robust defence of that one.
I haven't seen compelling critiques of it[0]. Curious to read them.
Their findings:
On medical/surgical vs. nothing:
"Wearing masks in the community probably makes little or no difference to the outcome of laboratory‐confirmed influenza/SARS‐CoV‐2 compared to not wearing masks (RR 1.01, 95% CI 0.72 to 1.42; 6 trials, 13,919 participants; moderate‐certainty evidence)"
On N95/P2 respirators vs. medical/surgical:
"The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the objective and more precise outcome of laboratory‐confirmed influenza infection (RR 1.10, 95% CI 0.90 to 1.34; 5 trials, 8407 participants; moderate‐certainty evidence)."
Thats a revision of a paper with roots back to 2006. I applaud them for having a rich source, but the primary objections can be understood to be in their apologia:
The original Plain Language Summary for this review stated that 'We are uncertain whether wearing masks or N95/P2 respirators helps to slow the spread of respiratory viruses based on the studies we assessed.' This wording was open to misinterpretation, for which we apologize. While scientific evidence is never immune to misinterpretation, we take responsibility for not making the wording clearer from the outset. We are engaging with the review authors with the aim of updating the Plain Language Summary and abstract to make clear that the review looked at whether interventions to promote mask wearing help to slow the spread of respiratory viruses.
The problem was how they communicated. The data is the data.
My opinion (feel free to have another one) is that it points to the need for training and more comfortable masks. The studies weren't WRONG per se, but they are very hard to interpret.
My whacky opinion: human facing sciences (medicine, psychology, diet, sociology, economics, etc.) have a huge problem with solutions that require motivation to succeed. In other words, if you are motivated, you can make masks work. If you are motivated, you can make intermittent fasting work. Same for EVs, Solar Panels, etc.
Their findings:
On medical/surgical vs. nothing:
"Wearing masks in the community probably makes little or no difference to the outcome of laboratory‐confirmed influenza/SARS‐CoV‐2 compared to not wearing masks (RR 1.01, 95% CI 0.72 to 1.42; 6 trials, 13,919 participants; moderate‐certainty evidence)"
On N95/P2 respirators vs. medical/surgical:
"The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the objective and more precise outcome of laboratory‐confirmed influenza infection (RR 1.10, 95% CI 0.90 to 1.34; 5 trials, 8407 participants; moderate‐certainty evidence)."
[0] https://www.cochranelibrary.com/web/cochrane/content?templat...