Recently, a study was done at the University of Pittsburgh in Pennsylvania on baby macaque monkeys.
The monkeys were divided into two groups. One group received the CDC recommended pediatric schedule of vaccinations from the late 1990s. The second group received no vaccinations.
…infant macaques receiving the recommended pediatric vaccine regimen from the 1990s displayed a different pattern of maturational changes in amygdala volume and differences in amygdala-binding of [11C]DPN following the MMR/DTaP/Hib vaccinations between T1 and T2 compared with non-exposed animals.
You can find the full study here.
Long story short, the vaccinated group displayed brain growth patterns that were enlarged and showed changes to the amygdala consistent with those found in autistic children.
The unvaccinated group had normal growth.
Among the vaccines used was the MMR (measles, mumps and rubella) vaccine, and others containing Thimerosal, a mercury based toxic substance that has slowly been phased out of many vaccines but are still present in others that are routinely administered today.
The infant macaque monkeys were chosen in particular because they are very similar to human infants, sharing over 95% of DNA with humans.
The full implications of this study remain to be studied, but the evidence is clear: vaccine safety research badly needs an overhaul. In the meantime it may be wise to do more research about the potentially harmful effects of vaccines.