|Vaccine immunology is the science of developing vaccines to prevent diseases. Vaccines trigger the innate immune system and also the adaptive immune system. A vaccine is a biological preparation that improves immunity to a particular disease. The best way to confer immune resistance to a pathogen is to mimic the pathogens without causing disease or to devise formulations which mimic its characteristics. Vaccines do not guarantee complete protection from a disease.
In some case, the infection may be less severe and heal faster. Vaccine-induced immune effectors are essentially antibodies produced by B lymphocytes and capable of binding specifically to a toxin or a pathogen. Other potential effectors are cytotoxic CD8+T lymphocytes that may limit the spread of infectious agents by recognizing and killing infected cells or secreting specific antiviral cytokines. Even if the host develops antibodies, the human immune system is not perfect and in any case the immune system might still not be able to defeat the infection immediately. Sometimes, this is because the host's immune system simply does not respond adequately or at all. This may be due to a lowered immunity in general or because the host's immune system does not have a B cell capable of generating antibodies to that antigen. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and remember it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.