Dr. I. Hope Alexander, Pittsburgh health director, congratulates Dr. Jonas E. Salk, with briefcase, after Dr. Salk arrived at the airport in Pittsburgh, Pa., April 16, 1955, from Ann Arbor, Mich., where this week the announcement was made that the Salk anti-polio vaccine was proved 80 to 90 per cent effective. One of Dr. Salk's sons, Peter, 11, center, smiles. Donna Salk, Dr. Salk's wife, smiles as she holds a bouquet of roses. (AP Photo/Paul Vathis)
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