At a boy’s fifteen-month well-child physical, the doctor noted that the boy was developing normally, though he did not want to talk. About nineteen months later, the boy received several immunizations, including the diphtheria-tetanus-acellular pertussis (DTaP) vaccination. About five hours later, the boy began experiencing an abnormally high fever and some swelling. The next day he was admitted to the hospital with a diagnosis of vaccine adverse reaction with secondary fever, angiodema, and anaphylactoid reaction. He was discharged the following day. However, three days after the vaccinations his mother called an ambulance because he was exhibiting signs of hypothermia and seizure-like episodes.
In the weeks and months following the administration of the DTaP vaccination, the boy’s vocabulary decreased, worrying his parents and his doctors. An MRI of his brain with and without contrast was normal, revealing a deep bilateral middle ear infection but no brain damage. Nonetheless, he continued to exhibit several seizure-like activities, but after a few months he was weaned off anti-epileptic medication. After observing his developmental delays and repetitive behaviors, a pediatric neurologist placed the boy in the autism spectrum disorder category.
The boy’s mother petitioned for compensation under the National Childhood Vaccine Injury Act (NCVIA), alleging that the DTaP vaccination caused her son’s focal brain injuries. The case was assigned to a special master who heard testimony from the mother’s medical expert. The medical expert opined that the boy experienced a two-phase anaphylactic reaction that included a delayed second state. The first phase of the anaphylactic reaction occurred before his hospital admission and the second phase occurred when his mother called for an ambulance. He pointed to medical literature that supported the existence of late-phase anaphylactic reactions and offered three possible mechanisms of injury that have been shown in medical literature to result from an anaphylactic reaction. However, the medical expert was unable to point to anywhere in the literature that described the sequence of events that presented in this case. The medical expert also admitted that he lacked any reliable medical evidence supporting the notion that anaphylactic shock could cause focal brain injuries. He testified that he had never seen an anaphylactic reaction lead to a focal brain injury, he did not find any support for a link in the medical literature, and he had an incomplete understanding of how the reaction could evolve into a focal brain injury.
After reviewing the evidence in the case, the special master alerted the mother that he found major gaps in her case and and allowed her to submit new evidence, updated medical records, and a revised expert report. After re-reviewing the entire record, the special master denied the petition. The mother filed a motion for review. The United States Court of Federal Claims sustained the special master's finding.
The United States Court of Appeals for the Federal Circuit affirmed holding that the mother failed to prove causation by a preponderance of the evidence and the special master did not improperly require the mother’s expert to provide proof of his proposed mechanism of injury.
The mother failed to prove causation by a preponderance of the evidence. To prove actual causation under the NCVIA in a non-Table injury case, a petitioner must show by preponderant evidence that the vaccination brought about the injury by providing: (1) a medical theory causally connecting the vaccination and the injury, (2) a logical sequence of cause and effect showing that the vaccination was the reason for the injury, and (3) a showing of a proximate temporal relationship between the vaccination and the injury. A petitioner who satisfies this burden is entitled to recover unless the government shows, also by a preponderance of evidence, that the injury was in fact caused by factors unrelated to the vaccine. A petitioner is not required to prove the case to a level of scientific certainty. To require identification and proof of a specific biologic mechanism in cases brought under the NCVIA would be inconsistent with the purpose and nature of the vaccine compensation program. However, simply identifying a plausible theory of causation is insufficient for a petitioner to meet the burden of proof. Instead, the statutory standard of preponderance of the evidence requires a petitioner to demonstrate that the vaccine more likely than not caused the condition alleged. The court found that in this case, although the mother’s medical expert hypothesized that the child suffered a two-stage anaphylactic reaction, the literature he submitted did not support the hypothesis. The medical expert proposed three possible mechanisms of injury that have been shown in medical literature to result from an anaphylactic reaction. However, there was no evidence beyond the expert's testimony suggesting that either the boy suffered a two-stage anaphylactic reaction or any of the three proffered mechanisms caused the boy’s injuries. The expert admitted that he had never before seen the sequence he posited as having occurred here. When asked to provide support for his theory that an anaphylactic reaction could cause a focal brain injury, the medical expert testified that he did not know whether his theory was generally accepted or even discussed in the medical community. He further testified that he had never seen an anaphylactic reaction lead to a focal brain injury, could not find support for it in the medical literature, and possessed an incomplete understanding of how the injury could evolve into a focal brain injury.
The special master did not improperly require the mother’s expert to provide proof of his proposed mechanism of injury. The special master merely required that the medical expert support his testimony with a reputable or scientific explanation that pertained specifically to the boy's case. The court held that the special master did not err in finding that the medical expert failed to do so. The medical expert proposed three mechanisms, but none were supported in any peer-reviewed study and there was no evidence beyond the medical expert's testimony suggesting that any of the three proffered mechanisms applied to the boy's case.
As the finder of fact, the special master was responsible for assessing the reliability of the expert's testimony by looking for reliable medical or scientific support, and in doing so, the special master was entitled to make determinations as to the reliability of the evidence presented to him and, if appropriate, as to the credibility of the persons presenting the evidence. The court noted that with regard to the medical expert's testimony, the special master stated that he found it necessary to address the credibility of the mother's expert, and noted that the testimony in this case was as poor as any he had experienced in twenty years.
In cases brought under the NCVIA, petitioners must proffer trustworthy testimony from experts who can find support for their theories in medical literature in order to show causation under the preponderance of the evidence standard. The level of specificity of such support may vary from circumstance to circumstance. The court noted that the special master in this case could properly find insufficient the reliance by the medical expert on a theory that was unsupported by the literature to explain a sequence he had never seen before. Given that conclusion, the basis for the mother's petition boils down to a temporal relationship between the administration of the DTaP vaccine and the boy's focal brain injuries. A temporal correlation alone was not enough to demonstrate causation.
The United States Court of Appeals for the Federal Circuit affirmed the Court of Federal Claims’ decision to sustain the special master's finding that the boy’s mother was not entitled to compensation under the NCVIA.
See: Londe v. Secretary of Health and Human Services, 2014 WL 1258137 (Fed.Cir., March 28, 2014) (not designated for publication).
See also Medical Law Perspectives, January 2013 Report:Vaccines: An Ounce of Prevention May Lead to a Pound of Injury