L.S. v. HHS - MMR, acute demyelinating encephalomyelitis (ADEM) (2024)

On February 27, 2018, Kevin and Danielle Sparrow, as parents and natural guardians for L.S., filed a petition for compensation under the National Vaccine Injury Compensation Program. They alleged that the measles, mumps, and rubella (MMR) vaccine administered to L.S. on February 6, 2015, caused her to develop acute demyelinating encephalomyelitis (ADEM).

L.S. was nearly six years old at the time of vaccination. Within days of receiving the vaccine, L.S. began experiencing symptoms including lethargy, fever, vomiting, neck pain, and a rash.

These symptoms led to multiple emergency room visits and hospitalization. Medical evaluations revealed inflammation in her brain (encephalitis), and she was diagnosed with probable ADEM, seizures, and other neurological issues.

The petitioners argued that the MMR vaccine caused L.S.'s ADEM through a theory of molecular mimicry. The Secretary of Health and Human Services disputed this claim, contending that L.S.'s initial symptoms were caused by a viral infection, which later evolved into ADEM.

Special Master Christian J. Moran issued a decision on March 19, 2024, denying compensation.

The Special Master found that the evidence preponderated in favor of a viral infection causing L.S.'s initial encephalitis, not the MMR vaccine. The Special Master noted that while L.S. did develop ADEM, the evidence did not support the vaccine as the cause.

The Special Master found that L.S.'s initial symptoms, including fever and neck pain, along with blood counts and spinal tap results, were more consistent with a viral infection. The Special Master also addressed the petitioners' theory of molecular mimicry, finding it lacked sufficient evidentiary support, particularly the lack of testing and peer-reviewed literature to establish a causal link between the MMR vaccine and ADEM in L.S.'s specific case.

The Special Master concluded that the petitioners failed to prove causation by a preponderance of the evidence. On review, Judge Stephen S.

Schwartz of the United States Court of Federal Claims issued an opinion on October 1, 2024, affirming the Special Master's decision. The court found that the Special Master's determination that L.S.'s condition was primarily viral in origin, and that the evidence did not support a vaccine-induced ADEM, was not arbitrary or capricious.

The court agreed that the petitioners failed to prove causation under the Althen standard, specifically noting the lack of evidence supporting the molecular mimicry theory and the Special Master's permissible evaluation of expert testimony. The court denied the motion for review and sustained the Special Master's decision.

The petition for compensation was denied.