A vaccine prepared from live microorganisms or viruses is known as what type of vaccine?

A vaccine prepared from live microorganisms or viruses is known as a live vaccine. This type of vaccine utilizes live but attenuated (weakened) forms of pathogens to stimulate an immune response without causing disease in the vaccinated individual. The immune system recognizes these live pathogens as threats, leading to the production of antibodies and the activation of T-cells, which prepares the body to recognize and combat the actual pathogen if encountered in the future.

Live vaccines tend to invoke a strong, durable immune response, often requiring fewer doses than inactivated or subunit vaccines. They are particularly effective because they closely mimic a natural infection, prompting a comprehensive immune response. In contrast, inactivated vaccines contain pathogens that have been killed or inactivated and do not elicit as robust an immune response as live vaccines. Modified live vaccines, while similar, refer specifically to those that have been altered so they do not cause disease; hence, they still retain some level of infectivity. Antitoxin vaccines involve the use of antibodies rather than the pathogen itself to confer immunity. Thus, the term "live vaccine" accurately describes the premise of a vaccine derived from live microorganisms or viruses.