“A June 2024 meta-analysis in the journal Clinical Microbiology Reviews synthesized evidence from more than 100 studies and reviews. It found that masks, “if correctly and consistently worn,” are “effective in reducing transmission of respiratory diseases and show a dose-response effect.” It also found that, N95 and KN95 masks were more effective than surgical or cloth masks. Using data from jurisdictions with mask mandates, the researchers concluded that “mask mandates are, overall, effective in reducing community transmission of respiratory pathogens.” The efficacy of masks alone does not settle the question of mask mandates, which is far more complex.
In their comprehensive 2024 report, Effectiveness of masks and respirators against respiratory infections, researchers associated with the Finnish Institute of Occupational Health reviewed 153 research articles on the effectiveness of mask use against infective agents or airborne droplets and particles. They reported that 128 of the articles they analyzed found masks to be effective. They noted that “systematic reviews of on randomized controlled trial studies in clinical or community settings demonstrated effectiveness in 10 out of 16 studies, and 20 out of 23 studies found mask mandates to be effective.”