This kind of thing is cooked up not to inform but to incite fear. What else would you do with a sign like this but try to scare people?
Autism is apparently the scariest thing that some people can imagine happening to a child and they have decided (against all evidence to the contrary) that vaccines are the cause. They've started a new "green our vaccines" movement to try to further their belief that vaccines cause autism. The above signs were to be trotted out for a "green our vaccines" rally in Washington DC yesterday.
I don't like repeating myself so I'm not going to say anything about the nonexistent causal relationship between vaccines and autism. But lots of others have been blogging about the "green our vaccines" movement.
There are plenty more blogs discussing the "green vaccines" thing. These are just the few that I have had the time to read in the last few days.