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 austere", wrote "The New York Times", "Salk the man is a person of great warmth and tremendous enthusiasm. People who meet him generally like him." A Washington newspaper correspondent commented, "He could sell me the Brooklyn Bridge, and I never bought anything before." Award-winning geneticist Walter Nelson-Rees called him "a renaissance scientist: brilliant, sophisticated, driven ... a fantastic creature." He enjoys talking to people he likes, and "he likes a lot of people", wrote the "Times". "He talks quickly, articulately, and often in complete paragraphs." And "He has very little perceptible interest in the things that interest most people—such as