The FDA's Covid-19 guidance for surgical masks states that manufacturers cannot make "filtration claims" for particles of any size and cannot be labeled "for antimicrobial or antiviral protection." The FDA states that "a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter...." However, the bulk of Covid-19 transmission occurs via microscopic aerosols around the size of 1 micron. Scientific studies have shown this is the case since near the outset of the pandemic. Scientific studies have also shown for more than a decade that the flu transmits in the same manner.