Charles M. Blow: Social distancing is a privilege

People like to say that the coronavirus is no respecter of race, class or country, that the disease COVID-19 is mindless and will infect anybody it can.In theory, that is true. But, in practice, in the real world, this virus behaves like others, screeching like a heat-seeking missile toward the most vulnerable in society. And this happens not because it prefers them, but because they are more exposed, more fragile and more ill.What the vulnerable portion of society looks like varies from country