| HOME |
| POLIO AND AMERICA |
| EARLY TREATMENT AND PREVENTION |
| THE POLIO
VACCINE |
| AMERICA AND THE VACCINE |
| BIBLIOGRAPHY |
The first clue to understanding polio was uncovered at the end of the nineteenth century when a Russian scientist discovered viruses, or germs that were much smaller than bacteria. The existence of viruses seemed to answer the question of why vaccinations only worked for certain diseases. Scientists deduced that if the virus traveled through the bloodstream, then vaccinations could be effective. When researchers began studying polio in the early twentieth century, they concluded that the polio virus was not carried through the blood. Therefore, vaccination was not a viable option for the prevention of polio.33
Nevertheless, the study of polio continued, but on a course away from vaccination research. Experimentation was limited, however, because it was believed that only humans could contract polio. Thus, the majority of research on polio only could be carried out through autopsies of polio victims. These limitations were overcome in the first decades of the twentieth century when Dr. Karl Landsteiner, an Austrian scientist, successfully infected monkeys with polio.34 Then, by the late 1930s, scientists finally were able to infect cheaper and more widely-available rodents with polio. However, most of the polio breakthroughs in the following decades remained dependent on the use of primates, including Dr. Salk's initial trials of his vaccine.35
Since vaccination seemed to be ruled out as a preventative option, many scientists followed different paths. A large contingent of American scientists understood polio as a disease that attacked the central nervous system through the nasal cavities. From this hypothesis, a team of American scientists produced a nasal spray to prevent polio. They then tested the spray on ten thousand subjects, and the results were a resounding failure: many of the subjects loss their sense of smell and no one received polio immunity.36
Despite the majority opinion that creating polio vaccinations was impossible, several scientists continued the search. In the mid-1930s, Dr. Maurice Brodie and Dr. William H. Park produced a killed-virus vaccine. Simultaneously, Dr. John A. Kolmer developed a live-virus vaccine. These scientists were all convinced that their vaccines were safe and effective; thus, they proceeded to vaccinate thousands of children in field trials. When some of those in the trials developed paralysis, the experiments were halted immediately.37 This initial failures created extreme caution in the scientific community, influencing the initial negative response and uneasiness when Salk announced his vaccine in 1955.
During the 1930s and 1940s, with the creation of the National Foundation for Infantile Paralysis and the subsequent increase in funding for and attention to polio, many breakthroughs emerged. First, scientists learned that various strains of polio existed, and by 1950 they isolated the three distinct types of the virus (called Types I, II, and III). Second, polio researchers ascertained that the polio virus existed in feces, which tied the disease to the gastrointestinal tract. Third, these
scientists
and researchers
realized that people could be polio carriers.38
One of the biggest breakthroughs in polio research occurred in 1949 when Dr. John Enders grew polio in a non-nerve tissue. This discovery affirmed that a vaccine was theoretically possible. A polio historian summed up the significance of Enders' discovery when she wrote that his "tissue-culture techniques transformed virus production the same way John Deere's plow and Cyrus McCormick's reaper transformed agriculture." In essence, it allowed for a polio vaccine to be "harvested" in large quantities for a cheaper price in a fraction of the time.39 Enders won the Nobel Prize in 1954 for his contribution to scientific advancement. By the early 1950s, a second major breakthrough occurred when Dr. Dorothy Horstman and Dr. David Bodian independently discovered that in the earliest stages of polio, the virus can be found in the blood--disproving the assumption that had guided polio research since the earliest days. Due to this discovery, Dr. William McDowell Hammon developed a temporary and limited method of polio protection based on injections of gamma globulin, a mixture of samples of adult bloods that contained polio antibodies.40 Lastly, with the development of the electron microscope in 1953, scientists were able to see the polio virus for the first time.41
All of this new knowledge allowed for greater understanding of the disease. Scientists now understood that polio enters the body through the mouth and travels through the digestive tract where it multiplies and is absorbed into the blood stream--this is when the initial symptoms appear. Paralysis then occurs when the virus enters the cells of the central nervous system. The degree of paralysis is determined by the strain of polio that the victim contracts. If antibodies are present in the blood before a person comes into contact with the virus, then they are immune. A polio vaccine would ensure this
protection. Thus, the final step in
solving the polio mystery was the development of the vaccine, and by
the 1950s it appeared to be only a matter of time. Dr. Jonas
Salk, however, reached the finish line first, beating out his numerous
competitors.After graduating from medical school in the early 1940s, Jonas Salk became a Research Fellow at the University of Michigan's School of Public Health. During this period, he conducted research as part of a war-time initiative that ultimately led to the development of an influenza vaccine. In 1947 he transferred to the University of Pittsburgh, taking a job as research professor. While in Pittsburgh, he became involved in a National Foundation-funded polio virus-typing program that expanded into larger-scale killed-virus polio vaccine research and experimentation. By 1952, the year of the country's most destructive polio epidemic, Salk had produced an experimental vaccine, grown in monkey kidney cultures and killed with the chemical formalin, which would protect against all three polio types.42 The only way to prove its effectiveness was to test it on human subjects.
He first
vaccinated himself, his family, and a small group of select
children. With positive results, he decided to carry out national
field trials in 1954. It was not hard to find "Polio
Pioneers"--parents willingly and readily signed up their children to
participate in the trials because the fear of doing nothing to prevent
polio was far greater than the fear of the vaccine.43
By
the end of the massive trials, close to two million children had
participated, some receiving the vaccine, others a placebo, while the
rest served as a control group.44 On April 12, 1955 Salk's polio vaccine was deemed to be "safe, effective, and potent," with a sixty to ninety percent success rate.45 The headlines on all American newspapers heralded victory over polio. Basil O'Connor, head of the National Foundation for Infantile
Paralysis, had anticipated success by
contracting with laboratories to begin producing the vaccine as early
as 1954, even though the trials still were underway.46
Consequently, when the government granted permission for the vaccine to
be distributed throughout the United States, there was a
stockpiled supply ready to be administered to
American children before the beginning of the dangerous summer
months.47 The initial jubilation was interrupted by a terrible incident. After just two weeks, the Surgeon-General of the United States announced that cases of polio had occurred following inoculations by vaccines produced at the Cutter Laboratories. On May 8 he halted all polio vaccinations for further testing and evaluation. The Public Health Service determined that new safety standards were necessary in order to assure that the vaccines contained only killed viruses. By the end of the month, polio vaccinations had resumed across the country. As a
result
of the Cutter mistakes,
seventy-nine vaccinated children contracted the disease and a hundred
and twenty-five others later contracted the disease from contact with
those infected. Eleven of those stricken had died.48 However, this proved to be the
only
major incident with
Salk's vaccine, as the annual cases of polio substantially dropped
until becoming virtually non-existent in the United States.
Over the course of the next four years, four-hundred and fifty million
doses of the vaccine were shipped across the country.49 Through science and cooperation,
America
conquered the polio virus and
eliminated a major threat that had haunted all Americans for over forty
years.