This case was reported in a literature article and described the occurrence of vaccination failure in a 32-year-old male patient who received Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine). 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, unknown after receiving Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine, the patient experienced vaccination failure (serious criteria hospitalization and GSK medically significant), Neisseria meningitides meningitis (serious criteria hospitalization and GSK medically significant), pericarditis (serious criteria hospitalization and GSK medically significant), headache (serious criteria hospitalization), fever (serious criteria hospitalization), unwell (serious criteria hospitalization), nuchal rigidity (serious criteria hospitalization), petechial rash (serious criteria hospitalization), pericardial effusion (serious criteria hospitalization and GSK medically significant), left ventricular systolic dysfunction (serious criteria hospitalization), lung congestion (serious criteria hospitalization and GSK medically significant), mental status changes (serious criteria hospitalization), jugular vein distension (serious criteria hospitalization), hyporesponsive to stimuli (serious criteria hospitalization) and stiff neck (serious criteria hospitalization). The patient was treated with ceftriaxone, Ampicillin and vancomycin. On an unknown date, the outcome of the vaccination failure, Neisseria meningitides meningitis, pericarditis, headache, fever, unwell, nuchal rigidity, petechial rash, pericardial effusion, left ventricular systolic dysfunction, lung congestion, jugular vein distension, hyporesponsive to stimuli and stiff neck were recovered/resolved and the outcome of the mental status changes was recovering/resolving. The reporter considered the vaccination failure, Neisseria meningitides meningitis, pericarditis, headache, fever, unwell, nuchal rigidity, petechial rash, pericardial effusion, left ventricular systolic dysfunction, lung congestion, mental status changes, jugular vein distention, hyporesponsive to stimuli and stiff neck to be related to Meningococcal polysaccharide groups A, C, W-135, Y conjugate vaccine. Additional information was provided. This case was reported in a literature article and described the occurrence of pericarditis due to Neisseria meningitidis serogroup W135 in a 32-year-old male patient who was vaccinated with unspecified quadrivalent meningococcal vaccine (manufacturer unknown). The patient had no significant past medical history was in his usual state of health. No information on patient's family history or concurrent condition or concomitant medication were provided. On an unspecified date, the patient received unspecified quadrivalent meningococcal vaccine (administration route and site unspecified; dosages unknown; batch number not provided). Age of vaccination was not provided. It was reported that the patient's immunization status was up-to-date. On an unspecified date, an unknown period after vaccination, the patient suddenly developed severe headaches and fever 3 days before presentation. The patient was found to have altered mental status and taken to a local emergency room. No sick contact, exposure history or recent travel was reported by his family. In the emergency room, the patient was minimally responsive to painful stimuli and appeared ill. His vital signs were: blood pressure, 89/60 mmHg, pulse rate, 110/min, respiratory rate, 23/min, temperature, 102.1 degree F and oxygen saturation 92% on room air. His neck was stiff with nuchal rigidity. The right jugular vein was distended. His heart sounds were weakly audible without apparent murmurs. His lungs were clear to auscultation. His abdomen was soft and not tender. Scattered petechial rash was observed on his palms and soles. Laboratory studies disclosed a white blood cell count of 18,500 cells/mm3 with 90% neutrophils, haemoglobin of 13.7 g/dL, and platelets of 202,000 cells/mm3. The level of sodium was 136 mmol/L, potassium: 5.1 mmol/L, bicarbonate: 23mEq/L, urea nitrogen: 18.0 mg/dL, creatinine: 0.6 mg/dL, erythrocyte sedimentation rate: 55 mm/h and C-reactive protein: 40.2 mg/L. The patient was empirically started on ceftriaxone, vancomycin, and ampicillin for possible bacterial meningitis. CSF analysis showed the following value- glucose: 23 mg/dL; protein greater than 300 mg/dL; and WBC count: 5040 cells/mm3 with 88% neutrophils. Gram stain of the spinal fluid showed gram-negative diplococci which was later identified as N. meningitidis. Electrocardiography revealed ST elevation with prolonged PR interval in multiple leads. Transthoracic echocardiography (TTE) demonstrated massive pericardial effusion with global left ventricular systolic dysfunction (ejection fraction 35%). A chest radiograph showed enlarged cardiac silhouette and pulmonary congestion. Urgent pericardiocentesis drained approximately 700 mL of turbid fluid. Gram-negative diplococci were seen on gram stain of the pericardial fluid. Cultures of the pericardial fluid and blood yielded N. meningitidis. The isolate was further identified as serogroup W135 N meningitidis. Vancomycin and ampicillin were discontinued, and the patient completed a 2-week course of ceftriaxone. The patient's altered mental status improved, and repeat blood cultures were sterile. The follow-up outpatient TTE demonstrated normalized cardiac function with resolution of pericardial effusion. This case has been considered as suspected vaccination failure being full schedule and time to onset was unknown. This case has been considered serious due to suspected vaccination failure/hospitalisation. The author did not comment on the relationship between pericarditis and unspecified quadrivalent meningococcal vaccine. However the author commented, "that pericarditis was due to hematogenous seeding of N. meningitidis into the pericardium after cultures of the spinal fluid, blood, and pericardial fluid all yielded N. meningitidis." The author concluded, "N. meningitidis can present with extra-meningeal involvement, including pericarditis. The frequency of such extra-meningeal meningococcal disease differs depending on N. meningitidis serogroups determined by chemical component of polysaccharide capsule. Serogroup W135 may involve extra-meningeal sites more frequently than other N. meningitidis serogroups. Recognition of meningococcal pericarditis is of great clinical importance since it can lead to massive pericardial effusion with cardiac tamponade that can lead to high morbidity and mortality."