text: Neuro COVID long haulers exhibit broad dysfunction in T cell memory generation and responses to vaccination The high prevalence of post acute sequelae of SARS CoV 2 infection PASC is a significant health concern In particular virus specific immunity in patients who suffer from chronic neurologic symptoms after mild acute COVID remain poorly understood Here we report that neuro PASC patients have a specific signature composed of humoral and cellular immune responses that are biased towards different structural proteins compared to healthy COVID convalescents Interestingly the severity of cognitive deficits or quality of life markers in neuro PASC patients are associated with reduced effector molecule expressionn in memory T cells Furthermore we demonstrate that T cell responses to SARS CoV 2 mRNA vaccines are aberrantly elevated in longitudinally sampled neuro PASC patients compared with healthy COVID convalescents These data provide a framework for the rational design of diagnostics and predictive biomarkers for long COVID disease as well as a blueprint for improved therapeutics 