The modern inactivated ("killed", if you consider a virus alive) polio vaccine is nearly perfectly safe though (other than one-in-a-million allergic reactions),

The modern inactivated ("killed", if you consider a virus alive) polio vaccine is nearly perfectly safe though (other than one-in-a-million allergic reactions), and can't give you polio. Nobody's used the live vaccine in the US since 2000. People don't generally get vaccinated against smallpox anymore because the pathogen has been eradicated.