A.G.C. v. HHS - Influenza, seizure disorder (2025)

On October 19, 2018, R.G.C. and S.S.C., as parents and legal representatives of their minor son, A.G.C., filed a petition alleging that the influenza vaccine A.G.C. received on October 20, 2015, caused him to develop a seizure disorder. A.G.C., who was five years old at the time, had a history of allergies, asthma, eczema, and autoimmune alopecia with eosinophilia.

He had previously received routine vaccinations, including yearly flu vaccines, without incident. Six days after his influenza vaccination, on October 26, 2015, A.G.C. experienced his first seizure, leading to hospitalization.

Initial evaluations at the University of Virginia (UVA) emergency department revealed seizures of unknown etiology, with potential diagnoses including viral encephalitis or autoimmune encephalitis. Over the following weeks and months, A.G.C. experienced multiple seizures, encephalopathy, and cognitive difficulties, including word-finding issues and behavioral changes.

Extensive medical evaluations ruled out many potential causes, including genetic and metabolic disorders. Testing for autoimmune antibodies like NMDA-R and VGKC was negative or inconclusive.

A.G.C. also tested positive for adenovirus. Petitioners' experts, Dr.

Stephen Nelson and Dr. Lawrence Steinman, proposed a theory of molecular mimicry, suggesting that the flu vaccine, in combination with a concurrent adenovirus infection, triggered an immune response that attacked the brain, leading to encephalitis and epilepsy.

Dr. Nelson opined that the flu vaccine and adenovirus infection could have allowed inflammatory cells activated by the vaccine to cross the blood-brain barrier and enter the brain, potentially targeting similar proteins (mimics) in the brain.

Dr. Steinman elaborated on this theory, explaining that both the adenovirus infection and the flu vaccine could trigger an immune response to contactin-associated protein like-2 (CASPR2), a protein associated with epilepsy.

He identified molecular mimics between CASPR2 and components of the influenza vaccine and adenovirus, suggesting this could lead to an autoimmune response. Respondent's experts, Dr.

Gregory Holmes and Dr. Andrew MacGinnitie, argued that the adenovirus infection was the sole cause of A.G.C.'s condition and that there was no plausible link between the flu vaccine and his neurological injury.

They cited a lack of epidemiological evidence and significant homology between vaccine components and brain proteins. Dr.

Holmes concluded that A.G.C. had adenovirus infection that resulted in encephalitis, and there was no plausible link to the flu vaccine. Dr.

MacGinnitie argued that the homology between the influenza vaccine and CASPR2 was not significant, that homology alone is insufficient to trigger autoimmunity, and that epidemiology shows no increased risk of encephalopathy or seizures after flu vaccine. The Special Master, Mindy Michaels Roth, found that petitioners presented a sound and reliable theory that the combination of the flu vaccine and adenovirus infection could cause encephalitis and epilepsy through an immune-mediated process, specifically molecular mimicry involving CASPR2.

The Special Master found a logical sequence of cause and effect, noting that both the adenovirus infection and the flu vaccine were substantial factors in causing A.G.C.'s condition, and that the onset of symptoms six days after vaccination was within a medically acceptable timeframe. The Special Master also found that respondent failed to prove that adenovirus was the sole substantial factor.

Therefore, entitlement to compensation was granted, and a separate damages order was to issue. The decision was originally filed on August 28, 2025, and reissued on November 10, 2025, after redactions.