The polio vaccine 50 years later: Key player reflects on vaccine's progress

On the 50th anniversary of the announcement that the Salk vaccine could protect against polio, the development team's sole survivor reflects on what was achieved.

By — Posted April 11, 2005

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Half a century ago in the United States, polio paralyzed more than 16,000 children and killed nearly 2,000 annually. That doesn't happen any more, and this achievement is due in part to the work of noted virologist Julius S. Youngner, ScD, the only survivor of the core team who, led by Jonas Salk, MD, developed an effective injectable killed virus vaccine.

Dr. Youngner joined Dr. Salk's team in 1949 and was responsible for much of the work toward large-scale production of the vaccine and methodology for safety testing of batches.

This month marks the 50th anniversary of the April 12, 1955, announcement that the Salk vaccine worked. The results were later published in the Aug. 6, 1955, issue of the Journal of the American Medical Association.

Dr. Youngner, who is now a distinguished service professor emeritus of molecular genetics and biochemistry at the University of Pittsburgh School of Medicine, spoke with AMNews.

Question: Why did you become so interested in developing a polio vaccine?

Answer: When it was indicated that we could have large-scale production of polio virus in cell culture, then it became a reality. Before that, polio virus had only been produced in monkey nervous tissue, and using that as the vaccine source had been tried in the '30s with some very unpleasant consequences.

Q: Were you working on other diseases at the time as well?

A: No. Exclusively on polio. It was like obsessional behavior.

Q: How did you feel about the fact that Dr. Salk tended to list only his own name on scientific papers leaving out other contributors such as you?

A: Betrayed. So did my other colleagues who can no longer speak for themselves. I'm speaking for all of us.

Q: What did you think of the work of Albert B. Sabin, MD, that led to the development of the oral vaccine?

A: Without Dr. Sabin's vaccine, polio would have never been eradicated because of the expense of the [Salk] vaccine and the fact that you needed needle and syringe. Multiple injections with needle and syringe made it not practical for global eradication. Dropping drops in babies' mouths was the way to go, and Dr. Sabin did it.

Q: How does it feel to have played such a significant role in eradicating this disease in the United States?

A: Exhilarating -- and that doesn't even describe it, because I've been on a high ever since.

Q: How do you feel about the fact that the world has still not managed to eradicate the disease despite significant effort?

A: The amazing thing is that they're still hopeful to do it by the end of 2005. There are teams going out into India and in Nigeria.

Nigeria was an example of what happens when you stop vaccinating. Not only did Nigerian children come down with polio, but countries around them in Africa developed polio. Why? Because they had eradicated it by immunizing all their children, but they didn't keep immunizing. The new children who were born were susceptible. It shows that until you eradicate the last case, you have to keep vigilant.

Q: Before the emergence of HIV, there was a point where it was thought that all infectious diseases had been defeated. Do you think we'll ever be able to actually defeat infectious disease entirely?

A: I really don't think so. Nature is the worst bioterrorist. There will always be new threats. Look at how AIDS appeared in the '80s. SARS came out of nowhere. In 2004, it disappeared, for the time being. Avian influenza in Asia is knocking on our doors. This could be the next pandemic, and nature knows how to do it.

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Ending polio

1908: Dr. Karl Landsteiner and Dr. Erwin Popper in Vienna identify a virus as polio's cause.

1935: Maurice Brodie, MD, and John Kolmer, MD, develop two competing vaccines. Neither worked, and several subjects in both trials die from the disease.

1953: Jonas Salk, MD, and his team develop an inactivated injected polio vaccine; 58,000 cases occur in the United States.

1954: 1.8 million children participate in vaccine field trials.

1955: Successful results of this trial are announced April 12. Vaccination begins in earnest.

1957: Trials of the Sabin vaccine begin in Russia.

1964: Only 121 U.S. cases of polio occur.

1979: Last U.S. case of polio caused by "wild" virus is documented.

1988: World Health Assembly passes a resolution to eradicate polio by the year 2000; it launches the Global Polio Eradication Initiative in conjunction with the Centers for Disease Control and Prevention, the United Nations International Children's Emergency Fund and Rotary International; 350,000 cases occur in 125 countries.

1993: Number of cases worldwide drops to 100,000.

1994: Western hemisphere is certified polio free.

1996: Last case of polio identified in China.

1998: Last case of polio in Europe occurs in Turkey.

1999: Number of cases around the world drops to 7,000.

2004: Only 1,170 cases occur in six countries worldwide. Majority are in Nigeria.

2005: Fourteen African countries that had been polio-free report cases linked to Nigeria. WHO aims to eradicate the disease by the end of the year.

Source: Rotary International, World Health Organization, UNICEF

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External links

Julius S. Youngner, ScD, University of Pittsburgh, School of Medicine (link)

Documents on Jonas Salk, MD, from the Dwight D. Eisenhower Library and Museum, Abilene, Kan. (link)

University of Michigan School of Public Health's commemoration of the April 12, 1955, polio vaccine trial announcement (link)

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