Vaccination: National and International Programs

As arguably the most cost-effective strategy for modern disease prevention, vaccination use has become more common throughout the 20th century. Of course, this is only effective if large segments of the population have been protected; the World Health Organization (WHO) estimates that “herd immunity,” or the protection from disease that occurs when a large segment of the population is vaccinated, exists when 95 percent of the population is compliant. While there are policies and programs that strongly encourage vaccination in the United States, including mandatory vaccination for schoolchildren and individuals in the military, nonmilitary individuals are able to exempt themselves or their children in order to keep these programs constitutional. The situation is similar in developed nations around the world.