If, at a trial in a special court, a preponderance of scientific evidence suggested that a vaccine caused one of these problems, a family would be compensated quickly, generously and fairly. Because no one could sue vaccine makers without going through this special court, the number of lawsuits against vaccine makers fell drastically.

Image Credit... Gérard DuBois

The system worked fine until a few years ago, when vaccine court judges turned their back on science by dropping preponderance of evidence as a standard. Now, petitioners need merely propose a biologically plausible mechanism by which a vaccine might cause harm  even if their explanation contradicts published studies. In 2006, for example, Dorothy Werderitsh claimed in the vaccine court that a hepatitis B vaccine had triggered an autoimmune response in her brain that led to multiple sclerosis. Two large studies had clearly shown that hepatitis B vaccine could neither cause nor exacerbate multiple sclerosis, but the court ruled in favor of Ms. Werderitsh, elevating a hypothesis above epidemiological evidence.

The Hannah Poling case is similar. In 2000, when Hannah was 19 months old, she received five shots against nine infectious diseases. Over the next several months, she developed symptoms of autism. Subsequent tests showed that Hannah has a mitochondrial disorder  her cells are unable to adequately process nutrients  and this contributed to her autism. An expert who testified in court on the Polings’ behalf claimed that the five vaccines had stressed Hannah’s already weakened cells, worsening her disorder. Without holding a hearing on the matter, the court conceded that the claim was biologically plausible.

On its face, the expert’s opinion makes no sense. Even five vaccines at once would not place an unusually high burden on a child’s immune system. The Institute of Medicine has found that multiple vaccines do not overwhelm or weaken the immune system. And although natural infections can worsen symptoms of chronic neurological illnesses in children, vaccines are not known to.

“There is no evidence that children with mitochondrial enzyme deficiencies are worsened by vaccines,” Salvatore DiMauro, a professor of neurology at Columbia who is the nation’s leading expert on the disorder, told me. Indeed, children like Hannah Poling who are especially susceptible to infections are most likely to benefit from vaccines.