There are some research showing that it helps. Other than the one linked in this post, here's a couple others: > Among nurses in Ontario tertiary care hospital

There are some research showing that it helps. Other than the one linked in this post, here's a couple others: > Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza. https://www.ncbi.nlm.nih.gov/pubmed/19797474 https://www.ncbi.nlm.nih.gov/pubmed/19797474 > during a severe pandemic when use of face masks might be greater, pandemic transmission in households could be reduced. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2662657/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2662657/ Also, purely anecdotally, in Hong Kong and Taiwan, virtually everyone are wearing masks when going out in public. Compared to other regions, the spread is much more limited despite the close proximity to China - Taiwan had blocked entry from China early on, but not Hong Kong. Lastly, even if it "only prevent the sick from spreading it", wouldn't it help with limiting the chance of the asymptomatic cases from from further spreading the disease? Now, if the general population purchasing masks is truly impacting the medical staff's supplies, then it's a legitimate reason to ask people to stop buying them. But telling them it is useless seems quite misleading.