15

CHAPTER

223

Vaccines and

Diagnosing Diseases

Would you pay your doctor to inject you with the flu virus? Of course not, but
that’s what millions of people do each year—and you might be one of them if you
get an annual flu vaccine. The flu vaccine contains some form of the flu virus or
an attenuated form.
Vaccines prevent you from catching a disease because they contain an ele-
ment of the disease. This element triggers your body to create an army of anti-
bodies that are trained to stamp out the disease if you contract it in the future.
There are many kinds of vaccines, each designed to prevent certain diseases.
You’ll learn about vaccines in this chapter. You’ll also learn how your immune
system is used to diagnose diseases.

What Is a Vaccine?

Avaccineis a suspension that contains a part of a pathogen that induces the
immune system to produce antibodies that combat the antigen. The concept of a

Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use.