A.W. v. HHS - Influenza, ADEM or viral encephalitis (2020)

On February 9, 2017, Priscilla Gonzalez, mother of A.W., filed a petition alleging that her daughter suffered acute disseminated encephalomyelitis (ADEM) or viral encephalitis as a result of an influenza vaccination received on November 24, 2014. A.W., born May 1, 2013, was approximately 1.5 years old at the time of vaccination.

Approximately five weeks after the vaccination, A.W. experienced vomiting and diarrhea for six days, leading to a gastroenteritis diagnosis. Subsequently, on January 27, 2015, A.W. was hospitalized with altered mental status and left hemiparesis.

Medical evaluations considered ADEM and viral encephalitis, with testing revealing a positive result for parainfluenza 3, which was considered a potential trigger. Treating physicians noted the possibility of post-viral ADEM or encephalitis due to parainfluenza, but none attributed the illness directly to the influenza vaccine.

Petitioner's expert, Dr. Craig Schacher, opined that the influenza vaccination indirectly contributed to A.W.'s condition by increasing her risk of parainfluenza 3 infection, but conceded that a post-infectious cause was statistically more likely.

Respondent's expert, Dr. Andrew MacGinnitie, opined that A.W. suffered viral encephalitis caused by parainfluenza 3.

Special Master Daniel T. Horner reviewed the case, noting that Dr.

Schacher's opinion was insufficient to establish a medical theory of causation (Althen prong one) and failed to demonstrate a logical sequence of cause and effect (Althen prong two), as it relied on statistical associations without establishing a biological link. Although a temporal relationship existed, the petition was dismissed for failure to establish a prima facie case.

The decision was issued on February 3, 2020. Petitioner was represented by Timothy M.

Kotfila, and respondent was represented by Jennifer Leigh Reynaud.