You have this from the WHO from December
https://www.who.int/publications/i/...of-the-novel-coronavirus-(2019-ncov)-outbreak
On page 4 you get this tidbit:
Evidence on the use of mask in health care settings Systematic reviews have reported that the use of N95/P2 respirators compared with the use of medical masks (see mask definitions, above)
is not associated with statistically significant differences for the outcomes of health workers acquiring clinical respiratory illness, influenza-like illness
Then you have this from the EU version of the CDC.
What did they say?
"The role of face masks in the control and prevention of COVID-19 remains an issue of debate. Prior to COVID-19, most studies assessing the effectiveness of face masks as a protective measure in the community came from studies on influenza,
which provided little evidence to support their use."
"Evidence for the effectiveness of non-medical face masks, face shields/visors and respirators in the community
is scarce and of very low certainty. Additional high-quality studies are needed to assess the relevance of the use of medical face masks in the COVID-19 pandemic."
This document provides an update to and complements the ECDC technical report on “Using face masks in the community: first update - Effectiveness in reducing transmission of COVID-19” published on 15 February 2021.
www.ecdc.europa.eu