Polio vaccine vaccine became widely available, it supplanted Salk’s injected vaccine, which had been tarnished in the public's opinion by the Cutter incident, in which Salk vaccines prepared by one company resulted in several children dying or becoming paralyzed. An enhanced-potency IPV was licensed in the United States in November 1987, and is currently the vaccine of choice there. The first dose of polio vaccine is given shortly after birth, usually between 1 and 2 months of age, and a second dose is given at 4 months of age. The timing of the third dose depends on the vaccine formulation, but should
Jonas Salk of my first year of medical school, I received an opportunity to spend a year in research and teaching in biochemistry, which I did. And at the end of that year, I was told that I could, if I wished, switch and get a Ph.D. in biochemistry, but my preference was to stay with medicine. And, I believe that this is all linked to my original ambition, or desire, which was to be of some help to humankind, so to speak, in a larger sense than just on a one-to-one basis." Concerning his last year of medical school Salk says: