1.0FactCheck.orghttps://www.factcheck.orgrich600338<blockquote class="wp-embedded-content"><a href="https://www.factcheck.org/2021/03/scicheck-the-evolving-science-of-face-masks-and-covid-19/">The Evolving Science of Face Masks and COVID-19</a></blockquote> <script type='text/javascript'> <!--//--><![CDATA[//><!-- /*! This file is auto-generated */ !function(c,d){"use strict";var e=!1,n=!1;if(d.querySelector)if(c.addEventListener)e=!0;if(c.wp=c.wp||{},!c.wp.receiveEmbedMessage)if(c.wp.receiveEmbedMessage=function(e){var t=e.data;if(t)if(t.secret||t.message||t.value)if(!/[^a-zA-Z0-9]/.test(t.secret)){for(var r,a,i,s=d.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),n=d.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),o=0;o<n.length;o++)n[o].style.display="none";for(o=0;o<s.length;o++)if(r=s[o],e.source===r.contentWindow){if(r.removeAttribute("style"),"height"===t.message){if(1e3<(i=parseInt(t.value,10)))i=1e3;else if(~~i<200)i=200;r.height=i}if("link"===t.message)if(a=d.createElement("a"),i=d.createElement("a"),a.href=r.getAttribute("src"),i.href=t.value,i.host===a.host)if(d.activeElement===r)c.top.location.href=t.value}}},e)c.addEventListener("message",c.wp.receiveEmbedMessage,!1),d.addEventListener("DOMContentLoaded",t,!1),c.addEventListener("load",t,!1);function t(){if(!n){n=!0;for(var e,t,r=-1!==navigator.appVersion.indexOf("MSIE 10"),a=!!navigator.userAgent.match(/Trident.*rv:11\./),i=d.querySelectorAll("iframe.wp-embedded-content"),s=0;s<i.length;s++){if(!(e=i[s]).getAttribute("data-secret"))t=Math.random().toString(36).substr(2,10),e.src+="#?secret="+t,e.setAttribute("data-secret",t);if(r||a)(t=e.cloneNode(!0)).removeAttribute("security"),e.parentNode.replaceChild(t,e)}}}}(window,document); //--><!]]> </script><iframe sandbox="allow-scripts" security="restricted" src="https://www.factcheck.org/2021/03/scicheck-the-evolving-science-of-face-masks-and-covid-19/embed/" width="600" height="338" title="“The Evolving Science of Face Masks and COVID-19” — FactCheck.org" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe>https://cdn.factcheck.org/UploadedFiles/doublemask.jpg720307Since the Centers for Disease Control and Prevention began recommending that members of the public mask up last spring, additional research has backed the use of face masks to combat the coronavirus, but knowledge gaps still remain. Here, we summarize the evidence.