Marco Cáceres

Because of the recent outbreaks of measles in the United States and the re-energized public debate about vaccines and vaccination policy, we’re again starting to hear references to the theory of “herd immunity.” The theory is the foundation for the mass vaccination campaigns around the world. It currently stipulates that in order to provide immunity to a population against contagious diseases like measles you must vaccinate at least 95 percent of the population. Theoretically-speaking, with a vaccination rate of 95 percent, the diseases should be eradicated.