UNDERSTANDING
VACCINES
CHAPTER 1
V
accines are designed to prevent people from
getting sick. When germs enter a person’s
body, they multiply and attack healthy cells. The
body uses three kinds of white blood cells to fight
back. They are macrophages, B-lymphocytes, and
T-lymphocytes. Macrophages remove germs from
the bloodstream. When a disease enters the body,
macrophages swoop in and gobble up germs. But
dangerous
antigens
are left behind.
Many vaccines are administered as shots.
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