First sentence in the authors' conclusion in the abstract of the updated Cochrane review on the efficacy/effectiveness of masks for the prevention of #covid and other respiratory diseases?
"The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions."
#CovidIsAirborn #MaskUpMovement
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6