What is the primary difference between a vaccine and an antibiotic?

• A. A vaccine triggers immunity to prevent disease; an antibiotic treats an existing bacterial infection by killing or inhibiting bacteria.
• B. Vaccines cure infections after symptoms appear.
• C. Antibiotics enhance immune memory.
• D. Vaccines are always effective after one dose.

Answer: (A)

This question hinges on the difference between preventing disease by training the immune system and treating an illness once it has started. A vaccine introduces a harmless part of the pathogen (or a blueprint) to the immune system, which then builds memory. If the person later encounters the real pathogen, the immune system responds quickly and prevents disease from developing. An antibiotic, by contrast, treats an active bacterial infection by killing or stopping the growth of the bacteria, helping the illness resolve, but it does not create lasting immunity or prevent future infections. Vaccines aren’t guaranteed to work after a single dose and often require boosters to achieve strong protection. They’re primarily preventive, whereas antibiotics are therapeutic for an established infection.