Two polio vaccines are used throughout the world to combat polio. The first was invented by Jonas Salk, and first tested in 1952 and announced to the world by Salk on March 26, 1953. It consists of an injected dose of killed polio virus. Albert Sabin[?] produced a cheaper and more effective oral polio vaccine in 1962.
... km². Of the total population of 26450, 13112 are male, and 13338 are female. The population density of the community is 18 inhabitants per km².
Externa ...