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 "I had an opportunity to spend time in elective periods in my last year in medical school, in a laboratory that was involved in studies on influenza. The influenza virus had just been discovered about a few years before that. And, I saw the opportunity at that time to test the question as to whether we could destroy the virus infectivity and still immunize. And so, by carefully designed experiments, we found it was possible to do so." In 1941, during his postgraduate work in virology, Salk chose a two-month elective to work in the laboratory of Thomas Francis at