Changes

The incidence of other diseases such as [[diphtheria]], [[pertussis]], and [[measles]], has decreased greatly from improvements in sanitation, increased awareness of the benefits of hand-washing and other preventive measures, and the invention of vaccines against these diseases.<ref>https://www.unicef.org/pon96/hevaccin.htm</ref>

The incidence of other diseases such as [[diphtheria]], [[pertussis]], and [[measles]], has decreased greatly from improvements in sanitation, increased awareness of the benefits of hand-washing and other preventive measures, and the invention of vaccines against these diseases.<ref>https://www.unicef.org/pon96/hevaccin.htm</ref>

While vaccines have been successful at preventing infectious disease, they have also resulted in controversy regarding their safety and effectiveness, legal and ethical issues surrounding mandatory vaccination, and whether children should be vaccinated against STDs<ref>https://www.historyofvaccines.org/content/articles/ethical-issues-and-vaccines</ref>

While vaccines have been successful at preventing infectious disease, they have also resulted in controversy regarding their safety and effectiveness, legal and ethical issues surrounding mandatory vaccination, and whether children should be vaccinated against STDs<ref>https://www.historyofvaccines.org/content/articles/ethical-issues-and-vaccines</ref><ref>https://www.nvic.org/NVIC-Vaccine-News/January-2018/are-vaccine-ingredients-safe.aspx</ref>

==Mechanism==

==Mechanism==