Parent asked for evidence that mass mask wearing prevent the spread of the disease. You presented a study that shows some masks if worn properly block some viru

Parent asked for evidence that mass mask wearing prevent the spread of the disease. You presented a study that shows some masks if worn properly block some viruses. Can you see how the study you presented doesn't answer parent post's question? Further, your study tests the first breath exhalation. > We screened 3,363 individuals in two study phases, ultimately enrolling 246 individuals who provided exhaled breath samples (Extended Data Fig. 1). Among these 246 participants, 122 (50%) participants were randomized to not wearing a face mask during the first exhaled breath collection and 124 (50%) participants were randomized to wearing a face mask. Overall, 49 (20%) voluntarily provided a second exhaled breath collection of the alternate type. So, your test says "when you put on a mask that mask will, immediately after you put it on, stop your exhaled breath hitting a plate placed in front of your mouth". It says nothing about how effective that mask is over time.