Health officials are now warning that Missouri is below the 95% vaccination rate needed for herd immunity against measles.

Herd immunity occurs when enough people in a group are immune to a specific infection that it cannot spread easily from person to person. Vaccination programs have been successful in creating herd ...

To stop the spread of an infectious disease like measles, you don’t have to vaccinate everyone. But you do have to vaccinate many. Just how many? To let you discover for yourself, we simulated an ...