Hilary Koprowski he is chair of the department of radiation oncology at Christiana Hospital in Delaware. While at Lederle Laboratories, Koprowski created the world's first polio vaccine, based on an orally administered attenuated polio virus. In researching a potential polio vaccine, he had focused on live viruses that were attenuated (rendered non-virulent) rather than on killed viruses (the latter became the basis for the injected vaccine subsequently developed by Jonas Salk). Koprowski viewed the live vaccine as more powerful, since it entered the intestinal tract directly and could provide lifelong immunity, whereas the Salk vaccine required booster shots. Also, administering a vaccine
Jonas Salk got in. During his years at New York University Medical School, Salk worked as a laboratory technician during the school year and as a camp counselor in the summer. During Salk's medical studies, he stood out from his peers, according to Bookchin, "not just because of his continued academic prowess—he was Alpha Omega Alpha, the Phi Beta Kappa Society of medical education—but because he had decided he did not want to practice medicine." Instead, he became absorbed in research, even taking a year off to study biochemistry. He later focused more of his studies on bacteriology which had replaced medicine