"Do you remember every time you've been sick? You may not, but your body does. With many illnesses, you can't get sick more than once because your body remembers and fights it off before you get sick again. But what if your body could recognize germs that you've never had before so you don't get ill? There's where vaccines come in! This book comes complete with extensive back matter all about types of germs and vaccines"-- Provided by publisher.