What is a prepared substance administered by injection to stimulate the body's immune response against a disease?

A vaccine is a prepared substance that is specifically designed to stimulate the body's immune response against a disease. It typically contains antigens that resemble a disease-causing microorganism, which can be in the form of weakened or inactivated parts of the pathogen or its toxins. When administered by injection, vaccines train the immune system to recognize and combat the pathogens they target, thus providing immunity or reducing the disease's severity if the person is later exposed.

Vaccines play a critical role in public health by preventing infectious diseases and have led to the control and eradication of certain illnesses globally. They differ from antibiotics, which are used to treat bacterial infections but do not stimulate the immune system in the same way. Placebos, on the other hand, are substances with no therapeutic effect and serve primarily in clinical trials for comparison purposes. Immunoglobulins are antibodies administered to provide immediate, passive immunity, rather than a long-term active immune response generated by vaccines. Therefore, the choice of vaccine is the most accurate response to describe a substance that prepares the body to fight future infections through an active immune response.