When a large majority of a community is vaccinated, the likelihood of a disease outbreak is greatly reduced. Herd immunity protects those who are not vaccinated. These people may be unvaccinated either by choice or for medical or religious reasons. The more vaccinated people there are in a community, the more unvaccinated people are protected against this disease. Another important aspect of herd immunity “is determined by the maturity and strength of an individual’s immune system” (“Herd Immunity,”