Prevention - Childhood Immunizations Save Lives

As once widely dispersed people began living close together, infectious diseases (like those shown on the chart) proliferated. Improvements in sanitation and quarantine were early methods of controlling the spread of disease. In 1796 Edward Jenner developed a vaccine against smallpox. Millions around the world were then dying of the disease each year, most of them children. By the early 20th century, five vaccines existed (against smallpox, rabies, diphtheria, typhoid fever, and plague), but they were not widely accepted or used. The chart shows the annual number of cases of various infectious diseases in various years before vaccines were widely used.

Disease epidemics cause great suffering. The 1918 influenza outbreak, first observed in a
U.S. Army barracks, led to 675,000 American deaths and at least 20 million worldwide. A popular theory of the time held that enemy German agents had unleashed this affliction on us. There was no treatment; the disease disappeared as mysteriously as it appeared.²⁰

The graphic shows that between 1951 and 1954, cases of paralytic polio averaged more than 16,000 annually. Polio, also called infantile paralysis, is a dreadful disease that sentenced some of its young victims to a lifetime inside an "iron lung." No one knew where it came from, and parents lived in fear of its appearance. Ironically, the more highly developed a country's system of sanitation, the more vulnerable it was to the disease. In 1954 Dr. Jonas Salk presided over history's largest-ever field trial of a vaccine when 1.8 million American schoolchildren voluntarily received his remedy against polio.

Since 1946, the Centers for Disease Control has been orchestrating large-scale public health efforts to reduce the number of cases of infectious diseases around the world. The small graphic shows the results of these efforts in the United States — a dramatic decline in just 10 years (1990-99) in the number of cases of all vaccine-preventable diseases except pertussis (whooping cough).

Cases of Vaccine-Preventable Diseases: 1990-1999

Smallpox and polio are absent from this chart but are shown on the large graphic. The last case of smallpox in this country was reported in 1949. There has not been a single reported case of polio caused by the wild virus in this country since 1979. Cases of diseases that were once seen as a normal and unavoidable part of growing up fell 365% in a decade. Immunizations are called one of the greatest public health achievements of the 20th century.

Today vaccines against more than 20 diseases have been developed or licensed. Most are administered to children (adults are discussed later in this chapter). The success of vacci- nation programs inspired a new way of thinking about disease —"disease eradication," which holds that selected diseases can be eradicated from all human populations through worldwide cooperation. Smallpox was the first disease proclaimed eradicated by the World Health Organization. The debate now is whether the smallpox virus should be destroyed. Worldwide polio eradication is the new goal.

As infectious diseases seemed to disappear, we grew complacent. The past few decades have brought us Lyme disease, Rocky Mountain spotted fever, AIDS, genital herpes, chlamydia, Ebola, Hantavirus, and Legionnaire's disease. Current causes of concern are the growing problem of bacterial resistance and its effects on the treatment of infectious disease, and the possibility of bioterrorism. Next we look at immunization prevalence.

Sources: Chart 1: "Impact of Vaccines Universally Recommended for Children." CDC Fact Sheets. April 2, 1999: www.cdc.gov/od/oc/media/fact/impvacc.htm. Chart 2: National Center for Health Statistics. Healthy People 2000 Final Review. Table
20.: http://www.cdc.gov/nchs/. "A Brief History of Infectious Diseases.": http://www.bayerpharma-na.com/healthcare/. National Institute of Allergy and Infectious Diseases: http://www.nih.gov/niaid.