The Immune System | Why Should Everyone Be Vaccinated? | How and
When Are Vaccines Given? | How Safe Are Vaccines? A vaccine is a
biologically active substance designed to protect children and
adults from infections caused by bacteria and viruses. Vaccines
are also called because they take advantage of our natural
immune system’s ability to prevent infectious illness. To
understand how vaccines work, we need to consider how our immune
system protects us from infections. The Immune System Our bodies
are armed with a variety of methods to protect against
infectious microorganisms like bacteria and viruses. The most
sophisticated of these methods involve activating specific
immune system cells, some of which make proteins called
antibodies. For the immune system to effectively respond to an
infectious microorganism, the invader must carry some sort of
identification that immune cells can recognize and respond to.
These identifying markers are called antigens. Both bacteria and
viruses carry their own antigens. I