Final answer:
The Salk vaccine uses an inactivated virus and is administered by injection, whereas the Sabin vaccine contains a live attenuated virus and is given orally.
Step-by-step explanation:
The main differences between the Salk and Sabin polio vaccines are in their administration methods and whether they are composed of live or inactive viruses. The Salk vaccine, introduced in 1955, uses an inactivated (killed) virus and is administered via intramuscular injection. In contrast, the Sabin vaccine, which was licensed for use in 1962, contains a live attenuated (weakened) virus and is given orally. Both vaccines target the same population, primarily children, and are effective against all three serotypes of the poliovirus.
The Sabin vaccine mimics the normal route of infection (intestinal), thus providing robust intestinal immunity, which is crucial for stopping the spread of the virus in areas where polio is still endemic. However, because it uses a live virus, there is a risk of the attenuated virus reverting to a more virulent form, and this risk is avoided with the Salk vaccine's inactivated virus. The Salk vaccine is chosen by countries with low polio rates to avoid the risk of vaccine-derived polio.