Polio vaccine
The first successful demonstration of a polio vaccine was by Hilary Koprowski in 1950, with a live attenuated virus which people drank. This vaccine, however, was not approved in the United States. An inactivated polio vaccine, developed a few years later by Jonas Salk, came into use in 1955. A different, oral polio vaccine was developed by Albert Sabin and came into commercial use in 1961. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. The wholesale cost per dose for the oral vaccine in the developing world is about US$0.25 as of 2014. In the United States, the inactivated form costs between $25 and $50.
Polio vaccine-3