Abstract
Treatment with eculizumab has revolutionized the management of complement-mediated disorders such as atypical hemolytic uremic syndrome (aHUS) and paroxysmal nocturnal hemoglobinuria (PNH). However, this therapeutic benefit comes at the cost of compromising a key arm of the innate immune response, which plays a crucial role in defending against encapsulated bacteria, including Neisseria meningitidis. As a result, patients receiving eculizumab are at a markedly increased risk of developing life-threatening meningococcal infections, even in the presence of prior immunization. This study analyzes the clinical presentation, diagnostic workup, immunological findings, therapeutic interventions and outcomes of two clinical cases of meningococcal meningitis under chronic eculizumab therapy. These cases illustrate potential challenges associated with current preventive strategies in patients receiving sustained complement blockade. Vaccine-induced immunity may not always translate into effective protection. Complement inhibition could also influence functional aspects of the immune response, raising uncertainties regarding the durability and clinical correlates of vaccination in this setting. These observations point to areas where preventive approaches may warrant closer evaluation and individualized consideration. These findings contribute to the ongoing discussion on how best to manage infection risk in patients treated with eculizumab. While no specific strategy can be firmly established, a patient-centered approach may support safer long-term management in this vulnerable population.