This case was reported in a literature article and described the occurrence of vaccination failure in a 4-year-old male patient who received Influenza vaccine for prophylaxis. Concurrent medical conditions included asthma (mild intermittent asthma, The patient was otherwise healthy). On an unknown date, the patient received Influenza vaccine at an unknown dose. On an unknown date, 152 days after receiving Influenza vaccine, the patient experienced vaccination failure (serious criteria hospitalization and GSK medically significant), influenza B virus infection (serious criteria hospitalization), methicillin-resistant staphylococcus aureus infection (serious criteria hospitalization and GSK medically significant), fever (serious criteria hospitalization), chest pain (serious criteria hospitalization), respiratory distress (serious criteria hospitalization and GSK medically significant), subcostal retraction (serious criteria hospitalization), pneumonia (serious criteria hospitalization and GSK medically significant), pleural effusion (serious criteria hospitalization), empyema (serious criteria hospitalization and GSK medically significant), lung consolidation (serious criteria hospitalization), general malaise (serious criteria hospitalization), generalized edema (serious criteria hospitalization), abdominal pain (serious criteria hospitalization), abdominal distension (serious criteria hospitalization), feeding intolerance (serious criteria hospitalization), ascites (serious criteria hospitalization and GSK medically significant), tachycardia (serious criteria hospitalization), pericardial effusion (serious criteria hospitalization and GSK medically significant), purulent pericarditis (serious criteria hospitalization and GSK medically significant) and subacute intestinal obstruction (serious criteria hospitalization and GSK medically significant). The patient was treated with Ceftriaxone Disodium, oseltamivir, vancomycin and Rifampin. On an unknown date, the outcome of the vaccination failure, influenza B virus infection, methicillin-resistant staphylococcus aureus infection, fever, chest pain, respiratory distress, subcostal retraction, pneumonia, pleural effusion, empyema, lung consolidation, general malaise, generalized edema, abdominal pain, abdominal distension, feeding intolerance, ascites, tachycardia, pericardial effusion, purulent pericarditis and subacute intestinal obstruction were recovering/resolving. The reporter considered the vaccination failure, influenza B virus infection, methicillin-resistant staphylococcus aureus infection, fever, chest pain, respiratory distress, subcostal retraction, pneumonia, pleural effusion, empyema, lung consolidation, general malaise, generalized edema, abdominal pain, abdominal distension, feeding intolerance, ascites, tachycardia, pericardial effusion, purulent pericarditis and subacute intestinal obstruction to be related to Influenza vaccine. Additional information was provided. This case was reported in a literature article and described the vaccination failure in a 4-year-old male child who was vaccinated with unspecified inactivated influenza vaccine (manufacturer unknown) for prophylaxis. The patient had mild intermittent asthma but was otherwise healthy. No information on patient's family or concomitant medication was provided. On an unspecified date, the patient received unspecified inactivated influenza vaccine (administration route and site unspecified; dosages unknown; batch number not provided). The age of vaccination was not provided. On an unspecified date, 5 months after vaccination, the patient presented with high fever and right-sided chest pain of 2 days duration. The patient was hospitalised. Upon admission, the patient's body temperature was 103.7 deg. F, heart rate was 160/minute, respiratory rate was 32/minute, blood pressure was 95/54 mmHg, and oxygen saturation was 95% on room air (normal range not provided for all). The patient was alert, interactive, in moderate respiratory distress with subcostal retractions, and no air entry on the right side. Nasopharyngeal swab was positive for influenza B. Chest X-ray showed right lower lobe pneumonia with pleural effusion and empyema with normal-sized cardiac silhouette. The patient was placed on high-flow nasal cannula. Intravenous ceftriaxone and oral oseltamivir were initiated. A right pleural pigtail catheter was inserted and drained 130 ml of serosanguineous fluid. Computed tomography (CT) scan showed a moderate to large loculated right-sided pleural effusion with complete consolidation of the right lung. The patient underwent video-assisted thoracoscopic surgery with pleural decortication and adhesiolysis. Pleural fluid culture grew methicillin-resistant Staphylococcus aureus (S. aureus), and vancomycin and rifampin were added to the antibiotic regimen. Clinical improvement did not occur as expected after video-assisted thoracoscopic surgery, with persistence of high-grade fevers and general malaise. The patient developed generalised oedema, diffuse abdominal pain and distension, and feeding intolerance. Plain X-ray of the abdomen showed multiple dilated loops of small bowel suggestive of subacute obstruction. Abdominal ultrasound revealed small amount of ascites and oedema surrounding the gall bladder. Persistent tachycardia and increase in respiratory distress warranted escalation of non-invasive respiratory support. On day 6 of hospitalisation, a chest X-ray showed enlarged cardiac silhouette. Echocardiogram showed a moderate circumferential pericardial effusion with thick fibrin stranding. Interventricular bounce was present, suggesting haemodynamically significant effects on diastolic function. Pericardial window surgery with drainage of effusion yielded 250 ml of yellow, cloudy fluid. The pericardial fluid did not grow any organism in culture. Multiple blood cultures were also negative. There was significant clinical improvement, and the patient was discharged home after receiving 4 weeks of intravenous vancomycin and rifampin. It was reported, the patient developed purulent pericarditis as a complication of methicillin-resistant S. aureus co-infection with influenza. This case has been considered as vaccination failure was unknown. This case has been considered as serious due to vaccination failure/hospitalisation. The patient was doing well on follow-up. The author did not comment on the events of Influenza B infection, community-acquired Methicillin-resistant S. aureus co-infection and unspecified inactivated influenza vaccine. The authors stated, "Preceding infection with influenza facilitates secondary bacterial infection through multiple immunological mechanisms. Influenza virus damages the epithelial layer of the tracheobronchial tree and enhances adherence of Staphylococcus. Influenza depletes resident alveolar macrophages 4 and suppresses nicotinamide adenine dinucleotide phosphate oxidase-dependent bacterial clearance, affecting phagocytic function of both neutrophils and macrophages. The virus alters the immune response of T cells and NK cells when challenged with secondary bacterial infection. Influenza and Panton Valentine leukocidin-producing S. aureus act together to induce inflammation and tissue damage in the respiratory epithelium by extensive neutrophil lysis and massive release of granule proteases, causing haemorrhage and tissue damage leading to necrotising pneumonias Purulent pericarditis is very rare, and has not previously been reported as a complication of methicillin-resistant S. aureus co-infection with influenza. Influenza affects a variety of host defence mechanisms predisposing to Staphylococcal co-infection, leading to severe and fatal complications in previously healthy children. It is likely that diastolic dysfunction resulting from reduced ventricular compliance owing to fixed pericardial volume in our patient contributed to these abdominal symptoms as a result of increasing right-sided cardiac pressures. Fever, tachypnoea, and tachycardia - all of which are signs of pericarditis are often attributed to underlying pulmonary or systemic infection when present. An enlarged cardiac silhouette is sometimes the only clue to the presence of pericardial effusion". Lab Comments: Lab tests were performed on an unspecified date. Nasopharyngeal swab was positive for influenza B. Chest X-ray showed right lower lobe pneumonia with pleural effusion and empyema with normal-sized cardiac silhouette. Computed tomography (CT) scan showed a moderate to large loculated right-sided pleural effusion with complete consolidation of the right lung. Pleural fluid culture grew methicillin-resistant Staphylococcus aureus (S. aureus). Plain X-ray of the abdomen showed multiple dilated loops of small bowel suggestive of subacute obstruction. Abdominal ultrasound revealed small amount of ascites and oedema surrounding the gall bladder. On day 6 of hospitalisation, a chest X-ray showed enlarged cardiac silhouette. Echocardiogram showed a moderate circumferential pericardial effusion with thick fibrin stranding. Interventricular bounce was present, suggesting haemodynamically significant effects on diastolic function. The pericardial fluid did not grow any organism in culture. Multiple blood cultures were also negative.