University of Pittsburgh had begun immunization experiments in monkeys using dead polio virus. Soon, however, Salk began to test inoculations in paralyzed polio patients and by 1953 human trials among the general population were initiated. By the spring of the following year, the largest controlled field trials in medical history were underway, and by 1955 the vaccine developed by Salk and his researchers was declared effective. By 1962, Salk's vaccine had reduced the incidence of polio in the United States by 95 percent. The breakthroughs in immunology and vaccine development at Pitt by Salk and his team are considered one of the most
Influenza vaccine sera (chiefly against what we now call "Hemophilus influenzae"—a name derived from the fact that it was originally considered the etiological agent—and several types of pneumococci). Only one therapeutic measure, transfusing blood from recovered patients to new victims, showed any hint of success." In 1931, viral growth in embryonated hens' eggs was reported by Ernest William Goodpasture and colleagues at Vanderbilt University. The work was extended to growth of influenza virus by several workers, including Thomas Francis, Jonas Salk, Wilson Smith and Macfarlane Burnet, leading to the first experimental influenza vaccines. In the 1940s, the US military developed the first