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HISTORY OF POLIO VACCINES Polio was first identified as a disease in the 19th century. Its occurrence became more frequent and in 1952 it claimed 57,897 victims in the United States alone. The federal government and private medical research facilities commenced an all-out effort to conquer the dreaded killer and crippler of so many children and adults. A major breakthrough occurred when Dr. Jonas Salk developed a killed or "inactivated" polio vaccine. This vaccine must be administered by injection. By 1955 the Salk vaccine was being distributed extensively in the United States and new cases of polio were reduced to less than 5,000 per year by 1959. In the late 1950's a new polio vaccine was developed by Dr. Albert Sabin and was widely tested in Europe. The Sabin vaccine is a live polio vaccine which contains greatly weakened or attenuated polio virus. The Sabin vaccine must be given orally. Although the Salk vaccine had greatly reduced the incidence of polio, the disease remained a significant health threat and pressure was mounting for a federally funded immunization program to bring the disease under control and, it was hoped, eliminate it. By 1961, the bitter controversy was in full bloom as to which of the two types of vaccines -- Sabin or Salk -- should be the weapon used in the battle against the disease. At that time only the Salk vaccine was being produced in this country although the Sabin vaccine had been used very successfully in Europe. The American Medical Association urged, in 1961, the use of the Sabin vaccine. The federal government solicited American drug firms to produce the Sabin vaccine. United States manufacturers of the Salk vaccine opposed the introduction of the Sabin vaccine. Three manufacturers agreed to manufacture the Sabin vaccine (including American Cyanamid). The Sabin vaccine rapidly replaced the Salk vaccine in the United States and no Salk vaccine has been manufactured in this country since 1968. American Cyanamid is the only United States firm manufacturing polio vaccine at the present time and it manufactures the Sabin type. In the last twenty-five years the Sabin v. Salk controversy has rolled on unabated. The minority Salk supporters, spearheaded mainly by Dr. Salk himself, have never ceased to advocate the superiority of the Salk vaccine in the numerous forums involving federal public health officials. The Sabin supporters include all major public and private health organizations and assert Sabin is the vaccine of choice. There are advantages to the Sabin vaccine. It is administered orally -- usually on a sugar cube to individuals old enough to eat sugar cubes. The Salk vaccine can only be injected through a needle. The injections are time-consuming and require individual administration by trained medical personnel. Further, injections are less well received by poorly educated persons and resistance thereto is stronger. Additionally, there is substantial medical evidence that the immunity induced by the Sabin vaccine is longer lasting and does not require boosters as may be necessary with the Salk vaccine. Ironically, the very cause of the longer-lasting immunity of the Sabin vaccine gives rise to the major drawback of this vaccine. The Sabin vaccine must be given orally, as the weakened virus gives immunity by proliferating in the intestines, thereby triggering the body's immune system. For reasons unknown, occasionally, but on a rather predictable ratio of incidence, the virus reproduced in the intestinal tract is a virulent virus, not the weakened Sabin virus. When this occurs, the individual receiving the virus, and persons in close contact with such individual, may acquire polio as a result of the vaccination. This unfortunate event occurs some five to ten times each year in the United States. This risk from the Sabin vaccine has been there from the beginning of its usage. It is a known risk and has been argued at every phase in the long-standing Salk-Sabin controversy. The very ability of the Sabin vaccine to infest others is, in the broad public health view, a plus factor. Unlike the Salk vaccine, the Sabin vaccine can vaccinate persons in contact with vaccinated persons because the intestines secrete the virus. Usually, the virus so secreted is the same weakened type as was used in the vaccine. Hence, such individuals are vaccinated without actual medical vaccinations. From a public health standpoint, more people can be so vaccinated than could otherwise be reached. Kansas requires polio vaccination before children are admitted to elementary school or state licensed child care centers or preschools. Being fully informed of this known risk, the federal government approved the Sabin vaccine and purchased large quantities of it for its mass public immunization program. The decision was made that the Sabin vaccine would be the weapon utilized to fight the serious public health problem of polio. The program has been so successful in reducing the incidence of "wild" polio that an individual in the United States now has about the same risk of contracting "wild" polio as he or she does of contracting polio through vaccination or contact with a vaccinee. Virtually all of the Western world utilizes the Sabin vaccine over the Salk vaccine in its public health programs. Finland, by virtue of a recent polio outbreak which included some individuals previously immunized by the Salk vaccine, is now using the Sabin vaccine in its public health program.
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