”Remember what the official word was...masks don’t work, but save them for health workers.”Three things:
One, nobody’s recommendations have changed with regard to “saving” masks: you should not be using medical-grade equipment, such as N95 masks or surgical masks. There is a shortage, and hospitals need it more.
Two, the CDC changed recommendations. The WHO still says they’re necessary only if you’re sick or caring for someone who is sick. Recommendations vary wildly by country, and there is far from consensus.
Three, the science is far from clear on the effectiveness of masks for the general public. At this point, it’s become
more religion than science:
https://www.oralhealthgroup.com/features/face-masks-dont-wor...
https://www.cidrap.umn.edu/news-perspective/2020/04/commenta...
(pre-emptive rebuttal: the WHO report which came out last week was a meta-review, and was very clear that there is no significant evidence supporting the use of non-medical masks for the general public. The review freely mixed source-control and PPE studies, which is questionable, at best. It showed that there may be a small effect if people wear medical equipment...the effect was actually about the same as for eye protection.
The only new papers with new, non-review data on masks since the beginning of the year are Leung, et al., which was statistically insignificant for all but one experiment, which was barely significant, and based on <10 data points. The other paper was about separating cages of hamsters with surgical mask material, which while interesting, is not a paper about masks.)