Currently there are two polio vaccines that are in use throughout the world to fight against polio. Jonas Salk, the man who invented the first, started his work on a vaccine in 1955. The vaccine worked in two steps: first a dose of killed polio virus is injected, and then an oral polio vaccine must be taken which contains a live but much weakened form of the virus. This vaccine was first tested in 1957 on humans, and was later liscensed in 1962.
Then came along another vaccine that was developed by Sabin. This live-virus vaccine quickly became to more popular route of the two for 4 main reasons:

1. Due to it's live state it has the ability to spread and to infect other individuals who have not been vaccinated. This sounds bad, but in the spread, it allows the remote body to build up some immunity to the virus.
   
2. Due to the fact that the oral vaccine performs its magic in the gut, it works on immunity there in the central system which in turn reduces the spread of the virus on the outside. If the polio vaccine is injected directly into the bloodstream it will immunize the inividual, however it does not not reduce his or her ability to spread the virus.
   
3. Everything is a matter of money these days, especially when it comes to healthcare. Sabin's "live" vaccine was cheaper than than Salk's "dead" vaccine.
   
4. The last reason for the increased popularity of Sabin's vaccine is that the oral vaccine is alot easier to widely administer to the general population than the injected vaccine. This means that patients are more likely to complete the series of vaccinations that are required to attain full immunity.

Sabin's vaccine is the standard treatment for polio to date. The dead virus was able to bring Polio to terms, however it was the live-virus vaccine that was able to completely eliminate the wild spread of the polio virus in the United States.