vaccine

a preparation that is administered (as by injection) to stimulate the body's immune response against a specific infectious agent or disease: such as an antigenic preparation of a typically inactivated or attenuated (see ATTENUATED sense 2) pathogenic agent (such as a bacterium or virus) or one of its components or products (such as a protein or toxin) - a preparation of genetic material (such as a strand of synthesized messenger RNA) that is used by the cells of the body to produce an antigenic substance (such as a fragment of virus spike protein). a preparation or immunotherapy that is used to stimulate the body's immune response against noninfectious substances, agents, or diseases.