A vaccine usually contains
- A. ready made antibodies against the pathogen
- B. killed or weakened pathogens, or antigens taken from them
- C. antibiotics that kill the pathogen
- D. living virulent pathogens in a small dose
Explanation
The point of a vaccine is to present the antigen without causing the disease, so the organism is killed, attenuated, or replaced by one of its surface proteins or an mRNA coding for it. The immune system responds as though to a real infection and leaves memory cells behind. A preparation of ready made antibodies is an antiserum, which treats rather than prevents and gives no lasting protection.