As great as memory cells are, obtaining them
through an infection is unpleasant and sometimes
dangerous. Vaccines are a way of tricking
our bodies into making memory cells, and becoming
immune to a disease. They pretend to be a
dangerous infection. One way of doing this
is to inject invaders that can’t do harm.
For example, by killing them, or by ripping
them into pieces. Our immune systems deal
with these kinds of vaccines pretty easily.
Sometimes, it’s necessary to make our immune
system work harder though, to produce even
more memory cells. Live vaccines are the real
deal. An enemy that can punch back is a bigger
challenge than a dead one. But this also sounds
like a sort-of horrible idea. What if the
germs win? To avoid that, we breed a sort-of
weak cousin of the real germ in the lab. Just
powerful enough to annoy the immune system,
and create enough memory cells.
Okay, so these are the basic principles of
vaccine use. They provoke a natural reaction
in our bodies that makes us become immune
against very dangerous diseases. Some, like
the flu virus, mutate so often that we need
a new vaccine every year, but most vaccines
protect us for years, or even a lifetime.
But, there’s a catch. Like everything in
life, vaccines have another side: Side effects.
What are they, and what happens if your child
develops one?
