BY THE NUMBERS
They rank among the most effective public health measures of all time, reducing or eliminating deaths from smallpox, polio, measles and many other diseases. When a vaccine for whooping cough was developed in the 1940s, deaths from the illness nearly disappeared. But while vaccination rates have risen in the United States in recent years, so has the number of parents opting out— usually because of missed follow-up appointments with doctors. This is largely due to a mistaken belief that the shots cause autism (they do not). As a result, the country is seeing a resurgence in whooping cough and measles.