Vaccine trial stages that collect information continuously on vaccine usage, adverse effects, and long-term immunity. Vaccine trials may take months or years to complete, since a sufficient time period must elapse for the subjects to react to the vaccine and develop the required antibodies. Poliomyelitis, a viral disease, has the potential to damage the central nervous system and leave children paralyzed. Jonas Salk developed an attenuated vaccine to combat the rising prevalence of the disease around the world. In 1955 the results from the preliminary trial of Salk’s vaccine were announced to the general public and within 2 hours it was licensed.
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