Peggy McCarter v. HHS - Influenza, polyneuropathy / alleged Guillain-Barre syndrome variant (2025)

On October 28, 2020, Peggy McCarter filed a petition alleging that an influenza vaccine administered on October 24, 2018 caused polyneuropathy, which she characterized as an atypical Guillain-Barre syndrome variant. She also received a pneumonia vaccine the same day, but the decision treated the influenza vaccine as the subject vaccine.

The public decision identifies her as an adult petitioner but does not state her exact age. Before vaccination, Ms.

McCarter described herself as active, walking several miles, swimming, and skiing. Two days after the vaccination she contacted EMS with nausea, weakness, diarrhea, fatigue, and lower-extremity weakness.

In the hospital, she reported bilateral leg aching and difficulty walking, but early neurologic findings were often normal or inconsistent: sensation was intact, reflexes were largely preserved, strength deficits varied, and providers documented self-limiting behavior. Treating physicians repeatedly considered GBS only a low or unlikely possibility, suspected viral syndrome or functional symptoms, and noted rapid improvement without IVIG during the initial hospitalization.

She later underwent rehabilitation and outpatient therapy, with continuing weakness complaints, and later EMG testing showed generalized demyelinating sensory peripheral neuropathy but no obvious motor involvement. Petitioner's expert, Stanford neurologist Dr.

Lawrence Steinman, opined that the vaccine caused acute sensory demyelinating polyneuropathy through molecular mimicry involving myelin basic protein or contactin-1, and that prior flu vaccines could support a rapid recall response. Respondent's neurologist, Dr.

Brian Callaghan, disputed GBS and argued that conversion disorder better fit the discordance between complaints and objective testing. Respondent's immunologist/rheumatologist, Dr.

Mehrdad Matloubian, also disputed GBS, criticized the proposed molecular mimicry targets, and argued that onset within roughly two days was too fast for the proposed immune process. Special Master Horner found that influenza vaccine can cause GBS generally, satisfying Althen prong one.

But he denied compensation on November 7, 2025 because Ms. McCarter failed to prove a logical sequence of cause and effect and failed to establish medically acceptable timing.

He gave weight to contemporaneous records showing preserved reflexes, normal motor studies, rapid improvement without treatment, inconsistent weakness, fever, leukocytosis, abdominal symptoms, and provider concern for viral or functional causes. No compensation was awarded.