Basically every paper in the vaccine safety literature is plainly so confounded as to be useless. Since there are no Randomized Placebo Controlled (RPC) trials supporting vaccines, virtually all studies report on the association (or lack thereof) between vaccines and some iatrogenic condition. But parents who believe vaccines made their kids sick, stop vaccinating them, which systematically moves sick or vaccine damaged kids in the studies into the “low vaccine”, “low thimerisol”, or etc. bin. This invalidates most studies supporting safety (and the few remaining ones suck for other reasons). Numerous studies report incredible preventative effects for vaccines, presumably because of this corruption, like having more thimerisol or more MMR’s is strongly preventative of autism and other mental development issues[28][29][30], or like having more vaccines was strongly preventative of atopy, apparently even years before patients got the vaccines[31]. The fact this confounding factor is overlooked demonstrates extreme confirmation bias and is the defining factor of Cargo Cult Science according to R.P. Feynman.[32] The above is point 3 out of 10 from

http://lifeboat.com/blog/2016/06/the-top-ten-reasons-i-believe-vaccine-safety-is-an-epic-mass-delusion