How do you stop an anti-vaxer from drowning?

Take your foot off his head.

** Edit: Some people PM'd me to tell me they found this offensive. I reread it and I agree. Here is the updated version of the joke:

Q. How do you stop an anti-vaxer from drowning?

A. Take your foot off his or her head.

Again, I apologize to any feminists out there for my originally posted version.