There is an interesting parallel to all this with the question of lead in the environment, especially in paint.
For quite a while, there was a general sense that lead was only a problem with a big dose and that it was the parent's responsibility to protect their child from eating lead paint bits.
Eventually, due entirely to a small number of brave and persistent scientists who were brutally attacked, it became clear that even a small exposure to lead was very dangerous, that exposure could happen just from breathing lead paint dust and that it is impossible to protect a baby, toddler or child who is living in an environment with loose lead paint around. The number of conditions that turned out to be influenced by exposure to lead went way up. http://www.aacap.org/AACAP/Families_...havior_45.aspx
Even when exposed to small amounts of lead levels, children may appear inattentive, hyperactive and irritable. Children with greater lead levels may also have problems with learning and reading, delayed growth and hearing loss. At high levels, lead can cause permanent brain damage and even death.
How many children have been diagnosed with ADHD, for example, when they were really suffering from lead poisoning?
Recent studies have shown that even low levels of lead exposure can also affect the renal system.
Lead toxicity also affects the reproductive system in both genders.
Recent studies also demonstrate that the cardiovascular system is just as affected by acute and chronic levels of lead as any other system in the body.
Lead poisoning can also present clinically in adults or children in anemia.
Vaccines contain dozens of ingredients, have never been tested long-term, etc., etc. I would just state, sadly, that we have no idea at all of the possible effects of vaccinating generations of human beings.