Salk, Jonas E.

Jonas Salk (1914-1995) developed the first safe and effective vaccine for polio, a disease that killed or paralyzed many victims, particularly children.

Salk was born in New York City and received his medical degree from New York University in 1939. In 1942 he began working for a former teacher, Thomas Francis, Jr., to produce influenza (flu) vaccines, a project that continued until 1949. That year, as a research professor, Salk began a three-year project sponsored by the National Foundation for Infantile Paralysis (Polio), an organization also known as the March of Dimes.

Periodic outbreaks of polio, which attacks the nervous system, often caused death or a lifetime of paralysis, especially in children. It was a difficult disease to study because sufficient virus samples were hard to obtain and keep for study. Unlike bacteria, which can be grown in cultures, viruses need living tissue on which to grow. Once a method for preparing viruses was discovered and improved, enough material became available for research.

Three Viral Types

Salk first set out to confirm that there were three virus types responsible for polio. He then began to experiment with ways to kill the virus and yet keep its ability to produce an immune response. By 1952 he had produced a "dead" virus vaccine that worked against the three virus types. First the vaccine was tested on monkeys, then on children who had recovered from the disease, and finally on Salk's own family and children, none of whom had ever had the disease. Following large-scale trials in 1954, the vaccine was finally released for public use in 1955.

The Salk vaccine was not the first vaccine against polio, but it was the first to be found safe and effective. By 1961, there was a 96 percent reduction in polio cases in the United States. In the 1960s, the Sabin "live-virus" vaccine, developed by Albert Sabin (1906-1993), began to replace the Salk vaccine because it was given orally (by mouth) rather than by injection. The Salk vaccine, however, is still considered a triumph of medical science. In more recent years, Dr. Salk directed research in developing vaccines against cancer and AIDS. He died at the age of 80 in 1995.