Just to pick one example, recent outbreaks of Measles in the U.S. have started with an international visitor returning home to an area (like some wealthy parts of California ... ) where vaccination rates resemble those of less-developed countries. Why? Parents who chose to stick with their preconceptions instead of science. Are you aware that the researcher who reported that childhood vaccinations carried an autism hazard not only had the article retracted by the journal, but lost his medical license?
One reason I picked Measles is that you can get it by entering a room where an infected person was an hour before you. Another is that my wife almost died from it as a child. But you can get Hepatitis A from shellfish or an infected busboy in a kitchen. (Not to pick on busboys ... ) There are occasional cases in New York City, where I go, several times a week, and eat in restaurants. Why would you avoid vaccination?