OMG, read the whole warning. The paragraph you did not highlight is the point. It says will not prevent contraction. The point repeatedly stated is that a mask stops/limits YOU from spreading it. When you wear the mask you don’t expel as many droplets. I understand the goalposts have moved repeatedly, but when Trump is now even agreeing to wear a mask, I suspect there is some reliability and value to wearing a mask. Not sure what else to say.