When Religion Says No Vaccinations!
There are some religious groups that object to immunisation. This leads to a population of unimmunised people. When a population is not protected, it makes it very hard to "knock-out" disease. In turn there is an open door for widespread epidemic's. Between 1992 and 1993, there was an outbreak of polio in the Netherlands. The members lived in a relatively close community and most were not vaccinated.