The term "vaccine candidate" refers to a specific vaccine that is in development and undergoing testing for its safety, efficacy, and ability to prevent or treat a particular disease. Vaccine candidates are created through years of research and development by scientists who work on understanding the biology of viruses or bacteria causing diseases, developing methods to weaken or kill them without causing harm, and then testing these vaccines in clinical trials before they can be approved for public use. The term "vaccine candidates" refers to specific formulations that are being considered as potential options for future immunization programs.