Really? I figure the following: at a certain point the negative utility of getting a disease is greater than the negative utility of an allergic or worse react

Really? I figure the following: at a certain point the negative utility of getting a disease is greater than the negative utility of an allergic or worse reaction. This has already happened to smallpox, as we assume the only two remaining places that have them won't release theirs. At some point the same was likely the case for measles in the US, and is the case for polio and malaria in the US.