It tends to be a crap-shoot when it comes to celebrities and pet causes. Unfortunately many are grossly uninformed, but make a lot of noise like McCarthy. The interesting thing is McCarthy's son Evan may not even have Autism. Some medical experts have indicated that his seizures are indicative of Landau-Kleffner syndrome. Apparently seizures are not associated with Autism at all, which is what led to Evan's dianosis. On top of that, Evan is recovering and that is also something that does not happen with Autism.
Amanda Peet, a celebrity, does offer some celebrity balance to the autism-vaccine equation, but she's not quite as loud as McCarthy. Here's her PSA on the topic. You can also check out some facts on this blog I found.
