Scott Alexander analyzes a study suggesting cloth masks may be harmful, but remains cautiously in favor of their use despite the uncertainty.
Longer summary
Scott Alexander examines a 2015 study by MacIntyre et al. on the efficacy of cloth masks compared to surgical masks and no masks in healthcare settings. The study found cloth masks performed worse than both surgical masks and the control group, raising concerns about their safety. However, Scott notes several limitations of the study and its interpretation. He leans towards believing cloth masks are still better than nothing, especially for blocking outgoing pathogens, but emphasizes the high uncertainty in this life-or-death decision during the COVID-19 pandemic.
Shorter summary