Vaccines work by introducing weakened or inactivated forms of a pathogen into the body, triggering the immune system to produce antibodies and memory cells that protect against future infections.

Live attenuated vaccines contain weakened forms of the pathogen that are still capable of replicating, but are unable to cause disease. They provide long-lasting immunity and are commonly used for diseases such as measles, mumps, and rubella.

Toxoid vaccines contain inactivated toxins produced by bacteria. They induce the immune system to produce antibodies that neutralize the toxins, preventing the development of disease symptoms.

Subunit vaccines contain purified components, such as proteins or polysaccharides, derived from the pathogen. They are less likely to cause adverse reactions compared to live attenuated vaccines and are commonly used for diseases such as hepatitis B and influenza.

Immunotherapy aims to harness the power of the immune system to fight cancer. It involves various approaches that enhance the immune system's ability to identify and destroy cancer cells.

Antibody-drug conjugates are a type of immunotherapy that combines a monoclonal antibody with a cytotoxic drug. The antibody targets specific molecules on cancer cells, delivering the drug directly to the cancer cells, resulting in their destruction.

Immune checkpoint inhibitors work by blocking inhibitory signals on immune cells, such as PD-1 and CTLA-4. This allows the immune cells to become more active and effectively target and destroy cancer cells.

Adoptive cell therapy involves collecting and modifying a patient's own T cells, genetically engineering them to recognize and attack cancer cells, and then re-infusing them into the patient's body.

Cancer vaccines aim to stimulate the immune system to recognize and attack cancer cells. They contain tumor-associated antigens or modified cancer cells that trigger an immune response against cancer.

Virotherapy involves the use of oncolytic viruses, which are engineered to selectively infect and kill cancer cells while sparing healthy cells. The viruses replicate within cancer cells, causing their destruction and stimulating an immune response against cancer.

Adjuvants are substances added to vaccines to enhance the immune response. They stimulate the immune system to produce stronger and longer-lasting immunity against the pathogen.

Oral vaccines are administered through the mouth. They are typically used for diseases that are transmitted through the gastrointestinal tract, such as rotavirus and polio.

Memory cells are a type of white blood cell that provides long-term immunity against pathogens. They are generated during an initial infection or vaccination and remain in the body, ready to quickly respond to future encounters with the same pathogen.

Adoptive cell therapy involves genetically modifying a patient's own T cells to express receptors that recognize specific antigens on cancer cells. These modified T cells are then re-infused into the patient's body, where they can effectively target and destroy cancer cells.

Herd immunity occurs when a large proportion of a population is vaccinated, creating an indirect protection for individuals who are not vaccinated or cannot be vaccinated due to medical reasons. This reduces the overall incidence of the disease in the population.