What is a "vaccine" used for?

A vaccine is a substance used to prevent disease. It works by stimulating the body's immune system to recognize and fight off specific pathogens, such as viruses or bacteria. When a vaccine is administered, it typically contains weakened or inactive parts of a particular organism, or a blueprint for how to create a piece of the organism (like mRNA vaccines). This prompts the immune system to develop a response, including the creation of antibodies, which prepares the body to combat the actual pathogen should it be encountered in the future.

The purpose of vaccination is primarily to confer immunity so that individuals are protected from diseases before they have a chance to infect the body, thereby reducing the incidence of those diseases within populations. This preventative approach differs fundamentally from treatment options, which aim to manage or cure existing health conditions, and explains why the other choices do not accurately describe the role of a vaccine.