Final answer:
The flu vaccine helps people produce antibodies against the flu virus, reducing the risk of serious complications.
Step-by-step explanation:
The recommended flu vaccine helps people at risk for serious flu complications by stimulating their bodies to produce antibodies against the flu virus. These antibodies are specific to the particular flu virus strains included in the vaccine. By producing antibodies, the person's immune system can effectively fight against the flu virus and reduce the risk of serious complications.