Atypical Hemolytic Uremic Syndrome Occurring After Receipt of mRNA-1273 COVID-19 Vaccine Booster: A Case Report

Atypical hemolytic uremic syndrome (aHUS) is a subtype of thrombotic microangiopathy (TMA) characterized by a dysregulation of the alternative complement pathway. Here, we report on a 38-year old previously healthy woman who developed aHUS after injection of the booster Covid-19 vaccine. One day after this vaccine (mRNA-1273, Moderna,Spikevax®) she felt ill. Because of persistent headache, nausea and general malaise she went to the general practitioner who referred her to the hospital because of hypertension and acute kidney injury. A diagnosis of TMA was made. Her treatment consisted of blood pressure control, hemodialysis, plasma exchange and respiratory support. Kidney biopsy confirmed the diagnosis of acute TMA. Patient was referred for treatment with eculizumab. Renal function improved after initiation of this treatment. Genetic analysis revealed a pathogenic C3 variant. Covid-19 infection as a trigger for complement activation and development of aHUS has been described previously. While we describe the first case of aHUS occurring after a booster mRNA vaccine in a patient with an underlying pathogenic variant in complement C3, there is one reported case of aHUS occurring after CHADOx vaccine. Given the time frame, we hypothesize that the vaccine probably was the trigger for development of aHUS in this patient.