Although I think of vaccinations as obvious, I don't think anti-vaccine people are automatically dumb.

First as a disclaimer: I personally think vaccine is one of the greatest things that ever happened mankind, eradicating deadly diseases. This not an antivax post, simply my view on why I think a person automatically isn't dumb for believing vaccines are bad. Thinking it gives autism however, is pretty dumb and virtually nobody would stand to gain from doing that purposefully. I also think it's naive to think that people won't do atrocious things for economical gain, be it killing a man to get to his iPhone, deceiving an elderly person to steal their pension or even, if the gain is big enough, destroy million of lives. Although there is good in the world, evil is just as prominent.

Reason being is that is it a completely feasible scenario. Given that it'd be one taking for a spy-movie but fact remains, it's completely feasible. Big Pharma has nearly endless amount of funds. Our brains and bodies still contain more mysteries than we can even comprehend even with today's modern science. We can however, control human behaviour with various drugs. Ritalin, antidepressants and opiates to name a few. Drugs is basically something that tricks the brain. We can force someone to feel happy, sleep or become hyperactive. This is per definition mind control, to the furthest extend we know today and when used properly it serves us to great benefit.

Now, back to the whole spy-movie scenario. The most effective way to administer drugs is by injection. These injections are far superior to anything airborne, digestive or any other form of application in terms of their longetivity and potency. If the villain of the spy movie were to have found a way to bend humanity to his or her will, this would be the both the first and optimal form - injections.

Getting a large amount of humanity to willingly get these injections administered however, is a part perhaps even as tricky as developing this substance. Humans greatest fear is biologically their fear of death and disease. Our survival instinct surpasses any other of our instincts. There is a reason why you'll desperetly inhale while underwater when drowning, knowing there is no air but your body and instincts can't be fooled. Praying on this instinct would be optimal for this villains purpose. Already having a built platform with copious amounts of trust, in an environment you already control, makes this almost too easy for this villain.

Lastly, not vaccinating is retarded. The risk of not doing it by far outweighs consequences of any potential evil scheme in the background.

tldr; IF big Pharma really wanted to do what antivaxers claim, it's completely feasible and already an optimised scenario for their plans. Also, vaccinate yourself and your kids.