An antigen is the part of a germ (bacteria or virus) that the body's immune system can recognize and attack to prevent the germ from causing disease. In vaccines, the antigen is killed/disabled so it does not cause the disease; it does however prompt the immune system to produce protective antibodies that will protect you from the disease when you come in contact with it.
B-cells are specialized immune system cells that respond to germs and killed/disabled antigens in vaccines. Once activated B cells can produce protective antibodies whenever needed. These B cells give your body "memory" of the specific germ or antigen that allows your body to recognize and fight the actual disease.
Antibodies are protective substances made by your body's immune system's B cells in response to germs and killed/disabled antigens in vaccines. Once activated, B cells can produce protective antibodies to fight the actual disease whenever your body comes in contact with it.
Hib, or Haemophilus influenzae type b is a bacteria responsible for severe infections of the blood stream, lungs (pneumonia), brain and spinal cord (meningitis). It also causes dangerous swelling in body tissues such as the epiglottis in your throat. This alone can cause death by asphyxiation. Hib infections are not only fatal; they can leave victims with permanent brain damage. Hib disease was virtually eliminated until people stopped getting vaccinated for it.
Memory Cells
Memory cells are the antibody-forming "B cells" in the immune system that help your body recognize and fight disease if your body comes into contact with it. Memory cells are activated by an invading germ or vaccine and once activated, they remain in your body for life - hence the term, "memory cell".
MMR Vaccine
The MMR vaccine is an immunization to protect an individual from contracting measles, mumps and rubella (also know as German measles). In 2010 the England's General Medical Council declared that there is no link between the MMR vaccine and autism. They also concluded that the author of the study purporting a link between vaccines and autism committed deliberate fraud.
Also known as whooping cough, pertussis is a serious and potentially fatal infection that has begun to increase among individuals who are not vaccinated against it. Pertussis can lead to very long hospitalizations and is particularly dangerous for infants.
Thimerosal, also called ethylmercury, is an organic form of mercury that prevents bacteria from contaminating vaccines. This form of mercury is different from methylmercury (found in fish for example) which can damage the nervous system. Thimerosal has been used in vaccines for years with no evidence of harm. Even so, all pediatric vaccines, including the flu vaccine, are available in a thimerosal-free form.