Chickenpox is caused by the varicella zoster virus (VZV), a type of herpes virus. It was once a common childhood disease, but few kids get it today because there's a vaccine available. But herpes viruses can be zombies, lying dormant in your body for a long time and then causing a new outbreak. When chickenpox comes back, it's called shingles, and it's a lot more painful than chickenpox. Lucky for us, there's a vaccine now specifically for shingles. If you are over 50 and had chickenpox, you really should get the vaccine. Shingles is no fun at all. SciShow explains how all chickenpox and shingles can be so different and so far apart in time, yet cause so much misery.