Which statement best describes the role of vaccines?

Vaccines are designed to stimulate the immune system to recognize and fight specific pathogens, thereby reducing the risk of contracting particular infectious diseases. When a vaccine is administered, it introduces a harmless component (such as a weakened or inactivated form of the pathogen, or a piece of it) that prompts the immune system to develop an adaptive response. This response includes the production of antibodies and memory cells, which prepare the body to effectively fend off future infections by the same pathogen.

The role of vaccines is preventative rather than curative. They do not treat existing illnesses or directly eliminate pathogens that are already present in the body, nor do they provide a physical barrier against injuries. Instead, the prime function of vaccines is to enhance immunity, resulting in a decreased likelihood of illness and potential outbreaks, which is crucial for public health and individual protection.