Fully Vaccinated

Fully Vaccinated

(alt-text)

"You still can't walk into someone's house without being invited!" "What? Oh, I see your confusion. No, this vaccine is for a bat VIRUS. I'm fine with doorways and garlic and stuff."

What If? is now on YouTube!
Check out the first video for the answer to
“What if we aimed the Hubble Telescope at Earth?”
and follow xkcd’s What If? The Video Series channel to be notified about each new video.