I picked one at random (NVKP, "Diseases and Vaccines: NVKP Survey Results") and, while I needed to translate it to read it, it's clear (and loud!) about not actually being a scientific study.

"We fully realize that a survey like this, even on purely scientific grounds, is flawed on all counts. The sample of children studied is far too small and unrepresentative, we didn't use control groups, and so on."

Turns out the NVKP roughly translates to "Dutch Organization for those critical towards vaccines."

I understand being skeptical about vaccines, but the skepticism needs to go both ways