That is not a reasonable way to evaluate the situation. Sure, some people have broken immune systems, and there can be a new and different virus that evolves fr

That is not a reasonable way to evaluate the situation. Sure, some people have broken immune systems, and there can be a new and different virus that evolves from the old one but doesn't earn a distinct name. That doesn't count. He is immune. Similarly, we say that cars can cross the Golden Gate Bridge, despite the fact that the bridge could be destroyed (by bombing for example) or that one could call the NASA crawler-transporter a "car" that is 90 feet wide. Absurd, exotic, and rare possibilities don't change the basic truth. Vaccines do work like getting the illness, or less so. The illness is nearly certain to provide long-term immunity, but a vaccine is not quite so likely. Those who can't generate immunity will survive the vaccine but not the illness.