Jordan King was a typical baby. His parents called him vocal and vivacious. Then just before age 2, after a large battery of vaccinations, he simply withdrew from the world. The real scary thing was when I noticed he wasn't looking at us any more in the eyes," Mylinda King, Jordan's mother, said. William Mead was a Pottery Barn baby model and met all the typical milestones. Then, also at age 2, after a set of vaccinations, William became very ill and he, too, changed forever. In both children, batteries of tests revealed dangerous levels of the brain toxin mercury in their systems. Their only known exposure: the mercury preservative once widely used in childhood shots. Dr. Bernadine Healy is the former head of the National Institutes of Health, and the most well-known medical voice yet to break with her colleagues on the vaccine-autism question. In an exclusive interview with CBS News, Healy said the question is still open. "I think that the public health officials have been too quick to dismiss the hypothesis as irrational," Healy said. Healy goes on to say public health officials have intentionally avoided researching whether subsets of children are "susceptible" to vaccine side effects - afraid the answer will scare the public. CBS News has learned the government has paid more than 1,300 brain injury claims in vaccine court since 1988, but is not studying those cases or tracking how many of them resulted in autism."