Masks...
I'm so glad to see people point out to the original tweet quoted that masks are not there to protect him from everyone else, but rather vice versa, and I'm so glad people are quoting appropriate statistics.
COVID is airborne, it is well-known amongst the epidemiologists and they've been harping on about increasing air flow and air filtration (the Corsi-Rosenthal box, when used, has shown a distinct drop in transmission rates in schools and other places), so a large conference venue running their HVAC systems at full whack at the request of the conference organiser to exchange *a lot* of air per hour is the smart thing.
Yes, there will be people saying "wear the mask if you want to or don't if you don't but I'm vaxxed and don't need to" - To those I say "look at the statistics... we still have wave after wave after wave... they may not be the tsunami-like waves of early in the pandemic, but they are waves". Vaccination does not mean end of transmission. Vaccination does not mean end of this annoying and pernicious disease. It merely reduces the risk of you being severely affected by it. So, if you want to be completely careful of spreading anything, especially if you are asymptomatic and are *not* testing daily (or are testing daily and decided to ignore a positive result - yes, there are asshats that do that), you wear a bloody mask.
And CDC et al are still saying that COVID "can be airborne" (note, not "is airborne"). Epidemiologists disagree with that assessment, just like Independent SAGE in this country are...