What type of vaccine involves the use of heat or radiation to kill the pathogen?

Killed vaccines, also known as inactivated vaccines, are developed by using heat or radiation to eliminate the pathogen's ability to replicate while maintaining its ability to provoke an immune response. This process ensures that the pathogen does not cause disease, but the immune system can still recognize it and respond effectively.

These vaccines typically contain entire pathogens that have been killed, thus preventing them from causing illness. The immune response generated from a killed vaccine often encompasses the production of antibodies against the pathogen's antigens. However, because the pathogen is not live, killed vaccines may require booster doses to maintain immunity over time.

In contrast, attenuated vaccines use live but weakened forms of the pathogen, toxoid vaccines are based on toxins produced by bacteria that have been inactivated, and subunit vaccines include only fragments of the pathogen rather than the whole organism. Each of these alternatives operates on different principles regarding immunity and pathogen exposure.