Now revealed that Salk polio vaccine was a team effort

The cure for polio came as a result of the collaboration between Thomas Francis Jr. and Jonas Salk.

50 years ago on April 12, Salk's former teacher and mentor at the University of Michigan, Dr. Thomas Francis, declared at a packed news conference on that the vaccine was safe, effective and potent.

Crucial field tests had shown that the vaccine was 70 percent effective against the main polio strain and 90 percent against two others, but Salk shocked everyone by becoming infuriated by the suggestion that he had created a vaccine that was less than perfect, says Dr. Howard Markel University of Michigan's Centre for the History of Medicine.

Salk, a diminutive, sharp-tongued man, then attacked Francis' findings and insisted his potion might have been 100 percent effective if the government hadn't insisted on adding an antiseptic to it. In his tirade Salk never once mentioned all the work done by his colleagues at the University of Pittsburgh, and did not credit Harvard researchers John Enders, Frederick Robbins and Thomas Weller, who enabled the vaccine to be mass-produced by finding a way to grow it in monkey kidney tissue.

Dr. Julius S. Youngner, who worked with Salk in Pittsburgh and is the only surviving scientist of the core research team, says Salk was not generous in acknowledging his co-workers, and made the world think that he had done it all by himself. Youngner, embittered by Salk's behaviour left the team in 1957 but confronted Salk about his behaviour in 1993.

During World War II, Salk and Francis had developed a killed-virus vaccine against influenza. In 1947, Salk was recruited by Pittsburgh to establish a virus research program against polio, a rival, Albert Sabin, was doing similar research.

David M. Oshinsky, author of "Polio: An American Story" says this produced an intensely competitive atmosphere but ultimately both men were successful. Salk's vaccine carries no risk that the virus could mutate back into an infectious form; Sabin's, which came out seven years later, has been easier to use in developing countries. The two men were bitter enemies to their deaths, Sabin in 1993, and Salk in 1995.

Salk's son, Dr. Peter Salk, an AIDS researcher, regrets the controversy over credit and says there is no question, "this was a collaborative effort" involving the University of Pittsburgh, the March of Dimes and other researchers.

He does not feel there was an effort on his father's part to capture the limelight or focus the attention on himself, adding that his father even balked at having the Salk Institute for Biological Studies in La Jolla, Calif., named after him. He regrets the day 50 years ago, when his father behaved ungraciously in Michigan.

Francis was born in Gas City, Ind. and after earning his medical degree from Yale in 1925, he worked at the Rockefeller Institute and then New York University where he began to specialize in influenza research.

Salk was born in New York City, the son of Russian-Jewish immigrants. He attended City College of New York and then medical school at New York University, where he began research on influenza and where he met Francis, then department chair and a professor of bacteriology and the first American to have isolated the flu virus.

In 1941, Francis moved to the University of Michigan to head up its new School of Public Health. He built a virus laboratory and Department of Epidemiology that studied infectious diseases.

In 1942 Salk followed him on a research fellowship, where he again studied under Francis and learned more about vaccine development, laying the groundwork for what would become his defining discovery.

In 1947, he moved to the University of Pittsburgh Medical School and became involved with the National Foundation for Infantile Paralysis devoting himself to developing a vaccine against polio.

Salk's vaccine was a killed polio virus, which immunized but did not infect patients, an idea that stemmed from Francis' work with the influenza vaccine.

Mentor and protégé reunited again in 1953, when Francis was asked to design, supervise and evaluate the field trials of Salk's vaccine in a wide-ranging study that involved 1.8 million subjects in three different countries. He insisted on a double-blind format where neither those giving the shots nor the recipients knew whether they were getting the real vaccine or a placebo.

The vaccine worked. So began the eradication of the dreaded disease known as poliomyelitis.

News of the discovery was made public in Ann Arbor on April 12, 1955.