Until recently, many of the childhood vaccines contained thimerisol and squalene, both derivatives of mercury, one of the more damaging neurotoxins and very hard to secrete from the body. Aluminum has been used as an adjuvant in many of these same shots, also damaging to the brain. Seasonal flu vaccine still uses thimerisol. So many ingredients like these are considered safe, but considering efficacy rates hovering around 80%, one has to ask, is it worth the risk from these heavy metals, and that's if you believe the .gov efficacy numbers. There is a revolving door between Big Pharma and federal and state offices and that brings their credibility into question along with their motives. Cui Bono, follow the money, etc. Until the causes of autism are actually revealed, vaccines are a prime suspect. Don't expect the CDC or the FDA to change their tune anytime soon, they'll be culpable if it turns out to be true.