ABSTRACT
In the second part of the chapter we examine how knowledge of immunological memory has been used in medical practice to improve human health and survival through the practice of vaccination. e aim of vaccination is to induce a primary immune response and immunological memory by immunizing people with a form of the pathogen, or a part of the pathogen, that stimulates a protective adaptive immune response but does not cause disease. If the vaccinated people subsequently encounter the pathogen, they make a secondary immune response that eliminates the pathogen before it takes hold. In poor countries where infectious diseases are endemic and vaccines expensive, there are campaigns to make vaccines more accessible. In rich countries, where vaccination programs have successfully eradicated much infectious disease, there are campaigns to stop vaccination because of the side eects, some of which are real and others imagined.
