Abstract
Long COVID, or post-COVID conditions (PCC), affects a substantial proportion of adults and is characterized by persistent symptoms such as fatigue, postexertional malaise (PEM), cognitive dysfunction, and dysautonomia. At present, no Food and Drug Administration-approved therapies exist. Pemivibart (Pemgarda), a monoclonal antibody (mAb) authorized under Emergency Use Authorization (EUA) for preexposure prophylaxis in immunocompromised individuals, has not been studied for PCC but may theoretically facilitate clearance of viral antigens. We report three individuals with longstanding, debilitating PCC who received pemivibart infusion under EUA. Each experienced rapid symptomatic improvement, most notably in fatigue with PEM, dysautonomia, and cognitive dysfunction. One patient achieved resolution of her most limiting symptoms within a week and sustained functional recovery following repeat infusion. Another demonstrated significant gains across several symptom domains and was able to resume prior physical activities, although benefits waned after two to three weeks. A third with autoimmune comorbidities reported dramatic improvement in energy and cognition, and continued to feel well at six weeks. The rationale for this case series stems from emerging hypotheses that persistent viral antigens may contribute to the pathophysiology of Long COVID and that neutralizing antibodies could facilitate antigen clearance and symptom resolution. In the three cases, pemivibart infusion was temporally associated with rapid and meaningful improvement in fatigue associated with PEM, cognitive dysfunction, and dysautonomia, symptom clusters that often drive functional impairment in PCC. While the magnitude and duration of benefit varied among individuals, the consistent pattern of improvement supports further exploration of mAb therapy as a potential disease-modifying approach. These preliminary findings highlight the need for controlled, biomarker-guided studies to determine efficacy, durability, and patient subgroups most likely to respond. Pemivibart remains authorized only for preexposure prophylaxis in immunocompromised individuals and is not approved for the treatment of PCC.