…One of the fascinating aspects of the immune system is that it has a memory and the capacity to learn. Long ago physicians realized that people who had recovered from the plague would never get it again–they had acquired immunity. In order to have room for all the cells needed to match millions of possible enemies, the immune system stores just a few of each kind. When an antigen appears, those few matching cells multiply into a full-scale army. After their job is done, they fade away except that the system forever retains a “blue-print” for rapid reactivation should it ever be needed…
…The amount or concentration of a particular antibody that is in solution can be measured in a laboratory. This is called a “Titer Test”. Common sense would indicate that if a Titer Test revealed that antibodies for a particular disease already exist at appropriate levels–booster shots are not required!…