Polio vaccine, 50 years later

Fifty years ago Tuesday, on April 12, 1955, scientists announced that the polio vaccine developed by Jonas Salk could prevent the disease that paralyzed children and struck fear in parents' hearts every summer.

At a news conference at the University of Michigan, Thomas Francis Jr., who had led a year-long study of the vaccine, declared: "The vaccine works. It is safe, effective and potent."

People celebrated. Church bells rang. In 1952, there had been more than 57,000 cases in the USA, but within two years of Francis' announcement, the incidence of polio dropped as much as to 90%. The last naturally acquired case in the USA was in 1979.

Since then, international vaccination efforts have drastically reduced polio all over the world. Last year, says the World Health Organization, there were 1,263 cases, down from 350,000 in 1988. Scientists say they're on track to be able to declare the disease eradicated by the end of 2008.

The Global Polio Eradication Initiative began in 1988, led by WHO, the U.S. Centers for Disease Control and Prevention, the United Nations Children's Fund and Rotary International. Rotary's PolioPlus program, which began in 1985, has contributed more than $500 million to polio eradication worldwide.

Among celebrations marking the anniversary:

• The first Thomas Francis Jr. Medal in Global Public Health will be awarded to former CDC director William Foege, a senior adviser to the Gates Foundation, at the University of Michigan.

• The National Museum of American History opens a Whatever Happened to Polio? exhibit and a Web site, americanhistory.si.edu/polio.

• A symposium on the vaccine and the eradication effort is being held at the University of Pittsburgh, where Salk created the vaccine.