Since the late 1950's and the early 1960's, there has been a controversy between which type of polio vaccine should be used. Jonas Salk had first discovered the polio vaccine which was injected into the blood stream. It consisted of dead polio viruses which the body makes antibodies from. He used a dead strain of a virus which was uncommon at the time. Albert Sabin later came up with another polio vaccine which was taken orally. It consisted of 'weakened' polio viruses.
The body attacks the weakened polio virus and grows immune to it. The weakened virus isn't strong enough to create a full blown polio infection, but strong enough for the body to create antibodies to it. Occasionally, the virus does become strong enough and the person gets a polio infection, especially with people who have weakened immune systems due to treatments of other illnesses. This doesn't happen with Salk's vaccine since the polio viruses injected are dead. But are these risks worth it? Which type of vaccine should be used?
Sabin's vaccine is now used 99% of the time in the U.S. over Salk's vaccine. Approximately 100 million Americans had taken three doses of the Sabin vaccine by the mid 1964. It has many advantages over the vaccine Salk came up with. It is taken orally and kept in the refrigerator until administration time. The vaccination doesn't require any uses of needles. It can be put in sugar cubes or sweetened syrup. Therefore, it was easy to administer and is used widely in third world countries such as Africa. On the other hand, Salk's vaccine needed to be administered with a needle, which can be unsanitary in third world countries where they can't afford to use one needle or each person. The Soviets found out that the Salk vaccine was complicated to administer. (It takes 3 shoots to complete the vaccination.) It was therefore never widely used there.
The vaccine is 96% to 100% effective in a field test in the former Soviet Union and Czechoslovakia of 12.6 million people. It immunizes the digestive tract instead of the blood, unlike Salk's polio vaccine. It is also known that 'gut' immunity is better than blood immunity. The vaccination lasts longer than the Salk's vaccine so it doesn't require multiple doses throughout your lifetime.
After taking the oral vaccine, you could excrete live polio virus from their feces. This could infect unvaccinated adults who, for example, change the diapers of a baby who took this vaccine. This could be an advantage because you could become immunized secondhandedly. Therefore, not only the baby will be immune to polio, but also the adults that were around.
One assumption to make refrigeration an advantage is that the cost of a refrigerator is much cheaper than the costs of needles in the long run. The problem with this is that refrigerators could be used for other vaccinations and medicines instead of storing polio vaccination. Another assumption with the refrigerator is that there is electricity to run the refrigerator. In certain parts of the world, there isn't enough electricity to run enough refrigerators to store all the vaccines and medicines, since refrigerators require a great deal of energy. This could pose a problem in some country's. But as technology moves and expands throughout the world, this problem won't be a big deal in the future.
Another assumption of why Sabin's vaccine should be used, especially in third world countries, is that the country has resources to handle people who do come down with polio. Sabin's vaccine can cause polio, even though the risks are very low. In the U.S., approximately 3/4 of all polio cases are related with vaccinations and contracting the disease through the vaccine.