[the_benno]

This is an awfully confident statement that is unsupported by available evidence on covid transmission and health risks. On what basis do you say that in person classes are completely safe when reopening of indoor spaces has led to massive upticks in infections across much of the US?

[SamReidHughes]

It is certainly confident, but it is also supported -- modulo "completely" -- by our understanding of how effective masks are supposed to be, and infection rates in certain other (mask-wearing) countries.