infections
Overview of Immunization
Types of Immunization
There are two types of immunization: Active immunization Passive immunization In active immunization, vaccines are used to stimulate the body’s natural defense mechanisms (the Overview of the Immune System ). Vaccines are preparations that contain one of the following: Noninfectious fragments of bacteria or viruses A usually harmful substance (toxin) that is produced by a bacteria but has been modified to be harmless—called a toxoid Weakened (attenuated), live, whole organisms that do not cause illness The body’s immune system responds to a vaccine by producing substances (such as Antibodies and Vaccines that containlive but weakened organismsinclude Vaccination for tuberculosis (BCG—for tuberculosis) Chickenpox ( Varicella Vaccine ) Cholera (certain vaccines given by mouth) Ebola Virus and Marburg Virus Infections None Influenza Vaccine (only the nasal spray vaccine) Measles, Mumps, and Rubella Vaccine None Polio Vaccine (only the oral vaccine, which is no longer used in the United States) Rotavirus Vaccine None Smallpox None Typhoid Fever (only the oral vaccine) Prevention None Many vaccines work by stimulating the body’s natural defense mechanisms (the Overview of the Immune System ). In passive immunization, antibodies against a specific infectious organism (or the toxin produced by an organism) are given directly to a person. These antibodies are obtained from several sources: The blood (serum) of animals (usually horses) that have been exposed to a particular organism or toxin and have developed immunity Blood collected from a large group of people—called pooled humanimmune globulin People known to have antibodies to a particular disease (that is, people who have been immunized or who are recovering from the disease)—called hyperimmune globulin—because these people have higher levels of antibodies in their blood Antibody-producing cells (usually taken from mice) grown in a laboratory Passive immunization is used for people whose immune system does not respond adequately to an infection or for people who acquire an infection before they can be vaccinated (for example, after being bitten by an animal with rabies). Passive immunization can also be used to prevent disease when people are likely to be exposed and do not have time to get or complete a vaccination series. For example, a solution containing gamma globulin that is active against Chickenpox can be given to a pregnant woman who does not have immunity to the virus and has been exposed to it. The chickenpox virus can harm the fetus and cause serious complications (such as pneumonia) in the woman. Passive immunization lasts for only a few weeks, until the body eliminates the injected antibodies. 