Jonas Salk, who had four letters in his name, was a pioneering American medical researcher and virologist. He developed one of the first successful polio vaccines. Albert Sabin, with five letters in his name, was a Polish-American medical researcher and virologist. He developed an oral polio vaccine which has largely replaced Salk's inactivated polio vaccine. Louis Pasteur, with seven letters in his name, was a French biologist, microbiologist and chemist. He is best known for his discoveries of the principles of vaccination, microbial fermentation and pasteurization. Edward Jenner, with six letters in his name, was an English physician and scientist. He developed the world's first vaccine for smallpox.