Neisseria meningitides, serogroup undetermined/Neisseria Meningitis; bacterial meningitis; Unilateral hearing loss; Cough; Fever; Chills; Headache; Neck pain; Petechial rash; This case was reported in a literature article and described the occurrence of neisseria meningitides meningitis in a 17-year-old male patient who received Men ACWY-CRM NVS (Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine) for prophylaxis.  On an unknown date, the patient received Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine at an unknown dose. On an unknown date, 21 days after receiving Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine, the patient experienced neisseria meningitides meningitis (serious criteria hospitalization and GSK medically significant), bacterial meningitis (serious criteria hospitalization and GSK medically significant), hearing loss unilateral (serious criteria hospitalization and GSK medically significant), cough (serious criteria hospitalization), fever (serious criteria hospitalization), chills (serious criteria hospitalization), headache (serious criteria hospitalization), neck pain (serious criteria hospitalization) and petechial rash (serious criteria hospitalization). On an unknown date, the outcome of the neisseria meningitides meningitis, bacterial meningitis, cough, fever, chills, headache, neck pain and petechial rash were unknown and the outcome of the hearing loss unilateral was recovered/resolved.   The reporter considered the neisseria meningitides meningitis, bacterial meningitis, hearing loss unilateral, cough, fever, chills, headache, neck pain and petechial rash to be related to Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine.  Additional details were reported as follows: This case was reported in a literature article and described the occurrence of neisseria meningitides 17-year-old male patient who was vaccinated with unspecified quadrivalent meningococcal conjugated vaccine (manufacturer unknown) for prophylaxis. This case corresponds patient (case-1) reported in this literature article. The patient was male. Previously the patient was healthy with no prior significant infections or pneumonias. No information on patient's family history or concomitant condition was provided. On unspecified date, at the beginning of the training, the patient received unspecified quadrivalent meningococcal conjugated vaccine (administration route and site unspecified, dosage unknown; batch number not provided). The age of vaccination was not provided. On an unspecified date, 3 weeks after starting basic training and vaccination, the patient developed cough, fevers and chills, headache, unilateral hearing loss, neck pain, and a petechial rash. The patient was admitted to the intensive care unit for bacterial meningitis. Cerebrospinal fluid studies were consistent with the diagnosis, and PCR (polymerase chain reaction) testing detected N meningitides, serogroup undetermined. The patient had clinical and laboratory findings for neisseria meningitis and complement deficiency such as CH50 14 U/mL (40-60 range), C3 169 mg/dL (90-180), C4 17 mg/dL (10-40 range), C5 17 mg/dL (7-20), C6 Undetected (7.2-12.8), C7 9 mg/dL (4-11), C8 21.2 mg/dL (10.7-24.9), C9 41 mg/dL (6-29), IgM, IgG, IgA Normal, Diphteria, tetanus toxoid, and Hib titers Protected, Pneumococcal titers 9/14 protective more than 1.3 microg/mL, Genetic testing C6 variants detected (1. c.1879del (p.Asp627Thrfs.4)-pathogenic and C.143G more than A (p.Arg48Lys)-unknown significance. Immunologic screening was notable for a low CH50 and C6 was undetectable. Genetic testing of the C6 gene revealed a heterozygous recessive pathogenic variant, c.1879del, as well a variant of unknown significance, c.143G more than A, also heterozygous and recessive. This case has been considered as serious due to hospitalization. Treatment was unknown. On unspecified date, the patient recovered with left sensorineural hearing loss as sequelae of his infection.  The author commented, "Invasive meningococcal disease is a significant cause of morbidity and mortality and has been associated with complement deficiencies, particularly in the terminal pathway. Because vaccination has become widespread and population immunity to the virulent strains develop, complement deficiency should be suspected because these patients are more susceptible to the lower virulent strains. The complement system is a key player in innate immunity and a bridge between innate and adaptive immunity. Specific to meningococcus and other encapsulated bacteria, the terminal complement forms the membrane attack complex, which inserts into the outer layer of gram-negative organisms, causing cell lysis. Therefore, deficiencies in each of the terminal components C5-C9 have been reported and are associated with recurrent meningococcal disease". The author concluded, "Although patients with terminal complement component deficiency should be vaccinated to both the quadrivalent MenACWY and MenB vaccines, they will not be protected from other serotypes. Given the risk for recurrent and severe infection, identifying complement deficiency is critical for mitigating future infections and associated morbidity and mortality". This is 1 of the 2 valid cases reported in this literature article.      Lab Comments: On an unknown date, the patient underwent lab test. Genetic testing C6 variants detected (1. c.1879del (p.Asp627Thrfs*4)-pathogenic and C.143G more than A (p.Arg48Lys)-unknown significance. Genetic testing of the C6 gene revealed a heterozygous recessive pathogenic variant, c.1879del, as well a variant of unknown significance, c.143G more than A, also heterozygous and recessive.,