Will Falconer, DVM Moderator
Great question, Greg, and the answer is clear from Hahnemann's work via Pitcairn: often only a single dose is all that's needed to overcome the epidemic disease. Amazing, right? There's history behind this spanning back to the 1800's in serious epidemics.
I also fully expect the average person will have a very mild brush with the disease and may not even know they were sick, but will none the less build immunity and not be susceptible to reinfection.