Is the goal to prevent exposure/infection, or to prevent illness? Exposure doesn’t mean illness - that takes replication by the virus unless the initial infection is a massive viral load. A normal infection starts with a moderate or low load, then progresses to illness via replication.
The flu shot, when it works, decreases the level of illness by having antibodies already in the body that can fight off the infecting virus from day 1. With a new virus like CCP Wuhan, nobody has effective antibodies. The vaccine Fauci and company speak of will work the same way.
It is not about preventing infection by a virus. It is about preventing illness.
RE: Is the goal to prevent exposure/infection, or to prevent illness?
Seeing how Doctors and Healthcare workers are using HCQ for themselves, I would say their primary goal is to prevent infection.
Why? Because one can be infected and still be asymptomatic and that is DANGEROUS in a hospital setting with so many vulnerable people.
So, if it does not prevent infection, taking it is pretty useless and I would suggest saving it for AFTER you are infected.