To: Land Shark who wrote ( 1310613) 8/2/2021 3:37:34 PM From: Broken_Clock 1 Recommendation Recommended By Winfastorlose Read Replies (1) | Respond to of 1381711 Here is a snippet from your first link. Mask wearing is based on an observational study of households in China? LMAO! We had neary 2 years for scientists to do actual verifiable studies on mask efficacy and also the efficacy of various types of masks and there are ZERO studies. Direct Evidence of the Efficacy of Public Mask Wearing If there is strong direct evidence, either a suitably powered randomized controlled trial (RCT), or a suitably powered metaanalysis of RCTs, or a systematic review of unbiased observational studies that finds compelling evidence, then that would be sufficient for evaluating the efficacy of public mask wearing, at least in the contexts studied. Therefore, we start this review looking at these types of evidence. Direct Epidemiological Evidence.Cochrane ( 7) and the World Health Organization ( 8) both point out that, for population health measures, we should not generally expect to be able to find controlled trials, due to logistical and ethical reasons, and should therefore instead seek a wider evidence base. This issue has been identified for studying community use of masks for COVID-19 in particular ( 9). Therefore, we should not be surprised to find that there is no RCT for the impact of masks on community transmission of any respiratory infection in a pandemic. The study looked at the reduction of secondary transmission of SARS-CoV-2 in Beijing households by face mask use ( Only one observational study has directly analyzed the impact of mask use in the community on COVID-19 transmission. 10). It found that face masks were 79% effective in preventing transmission, if they were used by all household members prior to symptoms occurring. The study did not look at the relative risk of different types of mask.