Traditionally a few highly tested vaccines were mandatory for children to protect against deadly or severe diseases, such as [[smallpox]] and [[polio]]. In the 1990s, vaccine manufacturers began introducing and persuading states to require numerous additional vaccines for non-deadly and even sexually transmitted diseases. About one-third of the states have philosophical exemptions entitling parents to decline the vaccines; 48 out of 50 states have religious exemptions; all states have medical exemptions, but they are hardest to obtain.<ref>http://www.nvic.org/state-site/state-exemptions.htm</ref><ref>http://www.vaccinesafety.edu/cc-exem.htm</ref> | Traditionally a few highly tested vaccines were mandatory for children to protect against deadly or severe diseases, such as [[smallpox]] and [[polio]]. In the 1990s, vaccine manufacturers began introducing and persuading states to require numerous additional vaccines for non-deadly and even sexually transmitted diseases. About one-third of the states have philosophical exemptions entitling parents to decline the vaccines; 48 out of 50 states have religious exemptions; all states have medical exemptions, but they are hardest to obtain.<ref>http://www.nvic.org/state-site/state-exemptions.htm</ref><ref>http://www.vaccinesafety.edu/cc-exem.htm</ref> |