K.M. v. HHS - Hib, acute disseminated encephalomyelitis (ADEM) (2024)

On February 28, 2019, Mary Mullins, on behalf of K.M., filed a petition under the National Vaccine Injury Compensation Program alleging that K.M. suffered acute disseminated encephalomyelitis (ADEM) or other related conditions as a result of receiving a Haemophilus influenzae type B (Hib) vaccine and/or a pneumococcal conjugate (Prevnar) vaccine on February 29, 2016. The respondent argued against compensation.

The Special Master determined that the petitioner had provided preponderant evidence that the Hib and/or Prevnar vaccines caused K.M.'s ADEM, satisfying the burden of proof under Althen v. Secretary of Health & Human Services.

Petitioner is therefore entitled to compensation. The parties disputed diagnosis and onset.

Petitioner contended K.M.'s diagnosis was ADEM, while Respondent argued it was unclear or not ADEM. Petitioner argued for an earlier onset of symptoms, while Respondent argued for a later onset.

Causation was also disputed, with all three prongs of the Althen test at issue: whether the vaccines could cause the injury, whether the vaccines caused K.M.'s condition, and whether the onset occurred within a medically acceptable timeframe to infer causation. K.M. was born on February 27, 2015.

She received a Hib and Prevnar vaccination on February 29, 2016. Following vaccination, K.M. developed symptoms including irritability, lethargy, and an inability to sit or stand, leading to a diagnosis of ADEM.

Medical records indicated K.M. had recurrent ear infections and upper respiratory infections in the months leading up to and following her vaccination. Her symptoms progressed, leading to hospitalizations and extensive diagnostic workups, including MRIs, CSF analysis, and genetic testing.

Treating physicians initially suspected meningitis, encephalitis, and later ADEM. Concerns for leukodystrophy and other neurodegenerative disorders arose due to K.M.'s clinical course and MRI findings, particularly her lack of response to initial treatments and progressive neurological decline.

However, extensive genetic and metabolic testing did not reveal an underlying cause for a neurodegenerative disorder. Petitioner presented expert testimony from Dr.

Lawrence Steinman and Dr. Robert Shuman.

Dr. Steinman opined that the Hib and Prevnar vaccines caused K.M.'s ADEM through molecular mimicry, proposing three specific mechanisms involving phosphoglycerol in Prevnar, CRM197 in Prevnar, and tetanus toxoid in Hib.

Dr. Shuman agreed with Dr.

Steinman's theories and proposed an additional theory involving CRM197 cross-reacting with myelin oligodendrocyte glycoprotein (MOG). Both experts opined that K.M.'s diagnosis was ADEM and that the vaccines were a substantial factor in causing her condition, with Dr.

Shuman placing the onset of symptoms as early as March 2016. They relied on K.M.'s clinical presentation, MRI findings, CSF results, and extensive negative testing for alternative causes.

Respondent presented expert testimony from Dr. Michael Kruer and Dr.

Andrew MacGinnitie. Dr.

Kruer opined that K.M. more likely had an undiagnosed neurogenetic disorder, citing her clinical course, MRIs showing progressive atrophy inconsistent with typical ADEM, and lack of response to treatment. He agreed that K.M. met some criteria for ADEM but argued that her overall presentation and MRI evolution were more consistent with a neurodegenerative condition.

Dr. MacGinnitie, an immunologist, deferred to Dr.

Kruer on diagnosis but disagreed that the vaccines caused K.M.'s condition, finding the molecular mimicry theories unreliable and the temporal relationship too long. He opined that infections are a more likely cause of ADEM than vaccines and that K.M.'s symptoms began too late after vaccination to infer causation.

Special Master Nora Beth Dorsey found that K.M.'s diagnosis was ADEM, crediting the opinions of Petitioner's experts and treating physicians, and noting that while some MRIs showed leukodystrophy-like patterns, this can occur in rare cases of ADEM. The Special Master found that extensive testing ruled out alternative causes like infection, metabolic disorders, or genetic conditions.

The Special Master also found that the temporal relationship between vaccination and onset was medically acceptable, with evidence suggesting the immune response began in early April 2016, within a reasonable timeframe for vaccine causation. The Special Master concluded that Petitioner proved by a preponderance of the evidence that the Hib and/or Prevnar vaccines caused K.M.'s ADEM, satisfying all three prongs of the Althen test, and thus Petitioner was entitled to compensation.