Vaccination is the injection of a killed or weakened infectious organism in order to prevent the disease. In the United States and throughout the modern world, parents routinely get their children vaccinated to ward off measles and several other diseases which most people in the 21st century have never heard of.
In rare cases, vaccinations have side effects; so, some new and untested vaccinations are unpopular, and controversies have developed over whether the government has the right to vaccinate schoolchildren against the parents' wishes.
Some people are hesitant to take them due to toxins and unhealthy substances which are in Vaccines. Some contain some of what seem to be the strangest ingredients, such as Monosodium Glutamate (classified as an Excitotoxin), aspartame (artificial sweetener), formaldehyde, and aborted human fetal tissue (for diploid cells, etc.)  Others avoid them because some research has shown that they drastically increase the risk of autism.  Still more avoid them for religious reasons. Those who stay away from the vaccine often seem to avoid getting that disease by using natural means, like Vitamin D supplementation  or the use of other natural treatments.
- Hull, Janet. "Toxins In Vaccines." Toxins In Vaccines. Web. 3 Dec. 2015. <http://www.janethull.com/newsletter/0706/aspartame_in_the_pink_packet.php>.
- Heyes. "Whistleblower Goes Public: CDC Buried Data Showing Vaccines Increase Risk of Autism by 340%." Natural News. 21 Aug. 2014. Web. 3 Dec. 2015. <http://www.naturalnews.com/046552_MMR_vaccine_autism_CDC_whistleblower.html>.
- Biggar, Allison. "How to Prevent and Cure the Flu Naturally without a Vaccine." NaturalNews. 20 Nov. 2009. Web. 3 Dec. 2015. <http://www.naturalnews.com/027542_flu_cures_remedies.html>.
- The Vaccine Controversy: The History, Use, And Safety Of Vaccinations