Since the middle of the 20th century, childhood immunization has saved millions of lives. Thanks to the polio vaccine, children in the United States no longer face death and disability from this crippling disease. As of the 1970s, vaccination had wiped out smallpox—a disease that earlier in the century killed 300 million people worldwide. Many other serious infections, including meningitis and measles, are now rare in America's children because of the vaccines they get.
