Cochrane revisit topics from time to time to update their reviews as new studies appear. The question of mask effectiveness was reviewed in the past also. There's an interview with one of the authors of this round's review here:
So, a Cochrane review is a study which synthesises all available studies – all that we can find or identity – on a particular topic. It follows a highly structured format and is always preceded by publication of a protocol. All this is to minimise the bias. Also, it is extensively transparent. In this case we are looking at about 300 pages of review. Now, the review called “Physical interventions to interrupt or reduce the spread of respiratory viruses” is called in code A122 for short and I will be using that acronym simply because it is just too long a title. So the protocol was first published in 2006 and then the first version was published in 2007, updated in 2009, 2010, 2011, and then 2020, so this 2023 is the fifth update of this review. And the reason why we update the reviews is they are soon out of date if we don’t do that, especially in some fast moving topics.
This update didn't change the conclusions from any of the prior reviews.
Because masks are so politicized there were numerous attacks on Cochrane this time around, though nobody cared in any of the previous rounds. The Cochrane authors are aware of all the criticisms, but there were no justifications found in any of them to alter the conclusions of the review or their procedures for doing them.
> This update didn't change the conclusions from any of the prior reviews. ... The Cochrane authors are aware of all the criticisms, but there were no justifications found in any of them to alter the conclusions of the review or their procedures for doing them.
True. But as noted elsethread, Cochrane is not responsible for others misinterpreting the conclusions.
"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."
https://dailysceptic.org/2023/02/06/dr-carl-heneghan-intervi...
So, a Cochrane review is a study which synthesises all available studies – all that we can find or identity – on a particular topic. It follows a highly structured format and is always preceded by publication of a protocol. All this is to minimise the bias. Also, it is extensively transparent. In this case we are looking at about 300 pages of review. Now, the review called “Physical interventions to interrupt or reduce the spread of respiratory viruses” is called in code A122 for short and I will be using that acronym simply because it is just too long a title. So the protocol was first published in 2006 and then the first version was published in 2007, updated in 2009, 2010, 2011, and then 2020, so this 2023 is the fifth update of this review. And the reason why we update the reviews is they are soon out of date if we don’t do that, especially in some fast moving topics.
This update didn't change the conclusions from any of the prior reviews.
Because masks are so politicized there were numerous attacks on Cochrane this time around, though nobody cared in any of the previous rounds. The Cochrane authors are aware of all the criticisms, but there were no justifications found in any of them to alter the conclusions of the review or their procedures for doing them.