Strains that infect more hosts outcompete other strains. People are protected themselves from further infection by being less active / more careful. Sure, if th

Strains that infect more hosts outcompete other strains. People are protected themselves from further infection by being less active / more careful. Sure, if they also killed all hosts, they might themselves die, but it's more about infectiousness than lessening virulence, isn't it? Some infectious strains may be more virulent, some not.