[grey_whiskers]

The question then becomes, what is the viral load *typically* necessary to spread infection?
And does that depend on the exact portal by which the virus is introduced to the body?
Recall the Chinese doctor, who had not been to Wuhan, who caught it by sitting at a conference table, with a doctor who *had*...

[PA Engineer]

The question then becomes, what is the viral load *typically* necessary to spread infection?

I agree. One of the most important factors during this pandemic has not been addressed.

Many hospitals with exterior rooms and/or top floor rooms can be easily converted to negative pressure. Does the exhaust air then have to be HEPA filtered or can it be dissipated to the exterior of the hospital without spreading further infection?

Most homes can also be set up quickly (magnetic return air blocker, duct booster, exhaust window fan) with a negative pressure room. This is a priority factor moving forward.