Final answer:
The nasal flu vaccine contains a live virus and is only approved for use in individuals between the ages of 2 and 49, while the injected vaccine can be administered to both children and adults. However, both vaccines are effective in preventing influenza.
Step-by-step explanation:
The nasal flu vaccine and the injected flu vaccine differ in several ways:
A) The nasal vaccine contains a live virus: The nasal vaccine contains weakened influenza virions that can replicate in the nasal passages, but they do not cause serious flu symptoms. This live virus induces a protective immune response.
B) The injected vaccine is for adults only: The injected vaccine can be administered to both children and adults, while the nasal vaccine is only approved for use in individuals between the ages of 2 and 49.
C) There is no difference in efficacy: Both the nasal and injected vaccines have been shown to be effective in preventing influenza, although their effectiveness may vary from year to year depending on the circulating strains.