It is about effects, not efficiency. Among effects of face masks are oxygen deprivation, bacterial growth and so on. Yes, there are a lot of harms of face masks to study.

Also, why you omitted

The pooled results of RCTs did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection.

sentences form your quote? Numbers in article clearly show zero efficiency of masks.

So, yes, debate is over about efficiency in preventing viral infections transmission, but all that harmful effects of face masks had to be studied.

There is completely another catch in that study. There was no any verifiable scientific experiments conducted by authors, it is just a compilation of some statistics.

It is obvious that those face masks governments mandated during coronahoax absolutely can't work for preventing respiratory viral infections transmission, but no experiments conducted yet to practically prove or disprove that exact statement for obvious reasons. Nobody will give out a grant for such study, because those who giving out grants are exactly those who forced that stupid mask mandates. So, at best we are limited only with such metastudies yet.

It is about effects, not efficiency. Among effects of face masks are oxygen deprivation, bacterial growth and so on. Yes, there are a lot of harms of face masks to study.

Also, why you omitted

The pooled results of RCTs did not show a clear reduction in respiratory viral infection with the use of medical/surgical masks. There were no clear differences between the use of medical/surgical masks compared with N95/P2 respirators in healthcare workers when used in routine care to reduce respiratory viral infection.

sentences form your cite? Numbers in article clearly show zero efficiency of masks.

So, yes, debate is over about efficiency in preventing viral infections transmission, but all that harmful effects of face masks had to be studied.

There is completely another catch in that study. There was no any verifiable scientific experiments conducted by authors, it is just a compilation of some statistics.

It is obvious that those face masks governments mandated during coronahoax absolutely can't work for preventing respiratory viral infections transmission, but no experiments conducted yet to practically prove or disprove that exact statement for obvious reasons. Nobody will give out a grant for such study, because those who giving out grants are exactly those who forced that stupid mask mandates. So, at best we are limited only with such metastudies yet.