ABSTRACT
INTRODUCTION For more than a century, scientists and public health leaders have known that preventing infectious diseases is the most efficient form of health intervention. During the 20th century, medical research led to the development of vaccines that prevent a number of crippling, often fatal, childhood diseases. In fact, vaccines helped to reduce the health gap between rich and poor countries. Up until the 1970s, outside of the world’s richest countries most children did not get vaccinated against even a single disease. Following the successful eradication of smallpox in 1977, public health advocates and experts around the world collaborated to help build systems in developing countries to routinely provide infants with vaccination against six diseases-measles, diphtheria, pertussis, tetanus, poliomyelitis, and tuberculosis (using bacille Calmette-Gue´rin vaccine). By 1990, 75% of the world’s children received these ‘‘basic six’’ vaccines. In the history of international public health, there has been no other routine health intervention that has received such high coverage as infant vaccination.
