The review, titled "Physical interventions to interrupt or reduce the spread of respiratory viruses", was led by 12 researchers from esteemed universities around the world.
A meta-analysis conducted by the Cochran Institute — considered the “gold standard of evidence-based reviews” — has concluded that masks and even N95 or P2 respirators offer little to no protection against COVID-19.
The review dug into the findings of 78 randomized controlled trials to determine whether "physical interventions" — including face masks and hand-washing — lessened the spread of respiratory viruses.
The paper can be read here or here. See the "Main Results" section for a summary.