Polio

The first large field trial of Jonas Salk’s polio vaccine began on this date in 1954.

Salk said: “Our greatest responsibility is to be good ancestors.”

Outbreaks of poliomyelitis were first recorded more than a thousand years ago. The incurable disease is caused by a virus that attacks nerve cells and sometimes even the central nervous system itself; it causes muscle weakness and wasting, paralysis, and sometimes death. It didn’t kill as many people as other viruses like influenza, but it was highly contagious and it was difficult to determine how it was transmitted. Children were most often affected. The first major polio outbreak in the United States struck in 1894, near Rutland, Vermont; the virus claimed its most famous victim in 1921, when Franklin Delano Roosevelt contracted it after a swim. His legs were completely paralyzed. Roosevelt helped found an organization — originally called the National Foundation on Infantile Paralysis, but later the March of Dimes — to research and combat the disease.

Dr. Jonas Salk was leading the Virus Research Lab at the University of Pittsburgh when the March of Dimes approached him in 1947. They asked him to lead efforts to research and develop an effective vaccine. He discovered there were about 125 different strains of the polio virus; these could be grouped into three basic types. A vaccine needed to provide immunity to all three types to be considered effective. Salk gathered many different strains of the virus and “killed” or deactivated them by pouring formaldehyde on them. The dead but intact virus was then injected into a subject, whose body would begin to produce antibodies against the virus; the antibodies would enable the body to fight off any future infections. Salk tested the vaccine on monkeys first, and then began the first human trials in 1952. His chief competitor, Albert Sabin, was working on a live-virus form of the vaccine; Sabin claimed Salk’s vaccine wasn’t strong enough and called him “a mere kitchen chemist.” But Sabin’s vaccine took a long time to develop, and was still unstable, so the March of Dimes backed Salk’s method instead. Salk was so confident in the safety of his vaccine that he used himself and his children as early test subjects. All of them, including several other adult volunteers, produced antibodies to the virus without contracting polio.

By this time, there was tremendous pressure to find an effective way to control the disease: 1952 saw the worst outbreak in America’s history, with nearly 60,000 cases reported; more than 3,000 people died and more than 21,000 were left disabled. Salk knew that he needed to begin testing his vaccine on a large scale, and quickly. He set up a makeshift lab in the gymnasium of Arsenal Elementary School in Pittsburgh, and personally administered his vaccine to 137 schoolkids. A month later, he announced that the first trial was a success, and he soon expanded his efforts across the country. By the time the vaccine was announced to be safe and effective in 1955, 1.8 million schoolchildren had received the vaccine. Results showed that about 65 percent of test subjects became immune to poliovirus type 1, 90 percent to type 2, and 94 percent to type 3. It marked the beginning of the end of widespread polio outbreaks. The development and approval of Sabin’s competing oral vaccine, which was cheaper and easier to administer, advanced the cause even further.

Soon after the 1954 trials began, the New York Times reported, “This could mean that within the next three to five years polio, crippler of young and old alike, will join diphtheria, smallpox, typhoid and other formerly dreaded infectious diseases as plagues finally tamed and conquered by man.” In 1952, 60,000 people contracted polio in the United States alone; 60 years later, in 2012, polio cases numbered only 223 in the entire world. WA