The Human Immune System and Infectious Disease

| Essay on Immunizations | | | | Immunization is a procedure routinely used to improve the body's ability to overcome infection and protect against diseases caused by infectious agents. It works against a specific disease by training the immune system to rapidly recognize and eliminate the infectious agent that causes that disease, thus resulting in immunity. Protection can be acquired either by passive or by active immunization.Passive immunization involves transfer of antibodies obtained from an immune donor to a nonimmune individual and results in temporary immunity. Currently, antibody-based therapies represent a form of treatment for disorders induced by venoms or toxins and for viral infections. Injections of antibody preparations derived from immunized human donors are used for the prophylaxis and treatment of tetanus, rabies, and pneumonia caused by respiratory syncytial virus (RSV), as well as infections caused by hepatitis A virus, hepatitis B virus, and varicellazoster virus. Monoclonal antibodies are expected to replace preparations derived from human donors. However, at this time, only one monoclonal antibody has been licensed for an infectious disease (RSV infection). Active immunization induces an adaptive, longlasting immune response to a pathogen by introducing the killed or attenuated pathogens or antigens derived from the pathogens into the body. These nonpathogenic forms of the pathogen are the major component of a vaccine. Therefore, active immunization is routinely achieved by administering different types of vaccines. In the past 100 years, the use of vaccines (along with sanitation practices) has dramatically reduced the number of deaths caused by infectious diseases. Administration of vaccines results in the induction of a vigorous immune response, similar to the one that would be induced by natural infection. Vaccine administration may result in antibody responses, cellular responses, or both. A major feature of effective vaccines