suspected vaccination failure; meningococcal infection; multisystem organ failure; septic shock; neck stiffness; fever; headache; nausea; photophobia; diarrhea; vomiting; This case was reported in a literature article and described the occurrence of suspected vaccination failure in a 41-year-old male patient who received Men ACWY-CRM NVS (Meningococcal ACWY Vaccine (potential Menveo)) for prophylaxis.   Concurrent medical conditions included paroxysmal nocturnal hemoglobinuria and autoimmune hemolytic anemia. Concomitant products included eculizumab.   On an unknown date, the patient received Meningococcal ACWY Vaccine (potential Menveo). On an unknown date, unknown after receiving Meningococcal ACWY Vaccine (potential Menveo), the patient experienced vaccination failure (serious criteria GSK medically significant), meningococcal infection (serious criteria GSK medically significant), multi-organ failure (serious criteria GSK medically significant), septic shock (serious criteria GSK medically significant), stiff neck, fever, headache, nausea, photophobia, diarrhea and vomiting. The patient was treated with antibiotics nos (Antibiotic (Details Unknown)). On an unknown date, the outcome of the vaccination failure was unknown and the outcome of the meningococcal infection, multi-organ failure, septic shock, stiff neck, fever, headache, nausea, photophobia, diarrhea and vomiting were recovered/resolved.   The reporter considered the vaccination failure, meningococcal infection, multi-organ failure, septic shock, stiff neck, fever, headache, nausea, photophobia, diarrhea and vomiting to be related to Meningococcal ACWY Vaccine (potential Menveo).  The reporter considered the vaccination failure, meningococcal infection, multi-organ failure, septic shock, stiff neck, fever, headache, nausea, photophobia, diarrhea and vomiting to be related to Meningococcal ACWY Vaccine (potential Menveo).  Additional details were provided as follows: This case was reported in a literature article and described the suspected vaccination failure in a 41-year-old male patient who was vaccinated with unspecified quadrivalent meningococcal polysaccharide vaccine (manufacturer unknown) for prophylaxis.   The patient was airline passenger with current condition of paroxysmal nocturnal hemoglobinuria (autoimmune hemolytic anemia) and currently was on biweekly eculizumab (Soliris) therapy. No information on patient's family history  On an unspecified date in 2012, before beginning therapy, the patient received quadrivalent meningococcal polysaccharide vaccine (administration route and site unspecified, dosage unknown; batch number not provided). The age of vaccination was not provided. .(In this case, Eculizumab carries a FDA black box warning about meningococcal infections, with the recommendation that patients receive quadrivalent meningococcal conjugate vaccine at least 2 weeks before starting eculizumab therapy and a booster dose every 5 years thereafter).  On an unspecified date, unknown period after vaccination and 1 day before departure, the patient's symptoms had started with neck stiffness. On Flight, approximately 3 hours after departure, patient experienced fever with 105.4 degree F, headache, nausea, photophobia, diarrhea, and vomiting. Upon arrival, the patient was immediately transported to a local hospital, where he was in septic shock, which was followed by multisystem organ failure. Cerebrospinal fluid, obtained approximately 12 hours after initiation of treatment, was Gram stain- and culture-negative. Blood cultures, which were drawn before antibiotic treatment, were positive for Neisseria meningitides of indeterminate serogroup. Subsequently, the patient was diagnosed with meningococcal infection. On 2 June 2015, this case was notified to CDC. After intravenous antibiotic treatment, the patient recovered fully.  This case considered as suspected vaccination failure as time to onset was unknown. This case considered as serious due to suspected vaccination failure. The author commented, "In 2007, eculizumab became the first Food and Drug Administration (FDA)-approved therapy for paroxysmal nocturnal hemoglobinuria, a rare type of autoimmune hemolytic anemia. Eculizumab is a monoclonal antibody that inhibits activation of the complement system, thus rendering patients vulnerable to infection with encapsulatedorganisms such as N. meningitides. On the basis of the patient's history of eculizumab therapy, CDC initiated an aviation contact investigation for suspected meningococcal disease before receiving laboratory confirmation. Current CDC guidelines for meningoccal disease recommend that on flights of equal or more than 8 hours duration, passengers seated on either side of the patient and any crew with close contact to the patient receive postexposure prophylaxis. This case also highlights the importance of heightened clinical suspicion for meningococcal disease in patients on eculizumab therapy, regardless of vaccination history."