What molecular structure introduced by a vaccine is recognized as foreign by the immune system?
Answer
Antigen
Vaccines present the immune system with an antigen, which is a molecular structure derived from a pathogen, such as a protein coat piece or genetic code, that the body identifies as non-self.

Related Questions
What is the fundamental goal of vaccination regarding disease manifestation?What molecular structure introduced by a vaccine is recognized as foreign by the immune system?Where do antigen-presenting cells travel after engulfing vaccine material to show it to naïve cells?What cellular components are the biological archives responsible for long-term immunity?How quickly can effective antibody levels typically begin production during a secondary (anamnestic) response?What happens to the majority of B and T cells activated during the primary immune response after the perceived threat passes?What must an unvaccinated person's immune system do upon initial exposure to a real pathogen?What is the primary function of administering a booster shot?What measurement is often used by scientists to track long-term protection, reflecting the concentration of circulating antibodies?How does achieving immunity through natural infection compare to vaccination regarding associated risks?Why does vaccine protection sometimes decline over time?