but it strikes me that when you're sick, it is to some degree unethical to go out in public for fear of infecting people. for colds, okay, it comes with the territory, but i had a 103.5 fever, ultimately harmless to me but perhaps fatal to the very old or very young. (it's worth noting that in this actual case, i suspect that whatever i had wasn't contagious, since i have had this before, been around specific people a lot both times, and no one has caught it from me.)
so going out in public is in some sense committing probabilistic murder, and certainly inconveniencing people. of course, that's not a sufficient ethical situation to override personal choice (for instance, you do both of those when you drive due to car crashes and traffic, and no one is arguing that driving is unethical, although it is in some sense a prisoner's dilemma situation.) but it seems like to some extent you have an obligation to try not to infect people when you're sick; among other things, when you drive, everyone knows the facts, but when you're in public with few symptoms people can't really tell you're sick.
the post office seems clearly reasonable; one person, behind a plate of glass. but a crowded grocery store? who knows, i may have killed a 90 year old that day. i'm not exactly losing any sleep over it, but i definitely think the ethics of being sick are worth thinking about. of course, everyone i've mentioned this to thinks i'm being ridiculous, so who knows.