This case was reported in a literature article and described the occurrence of metapneumovirus infection in a elderly patient who received Influenza vaccine Quadrivalent. On an unknown date, the patient received Influenza vaccine Quadrivalent at an unknown dose. On an unknown date, an unknown time after receiving Influenza vaccine Quadrivalent unspecified season, the patient experienced metapneumovirus infection (serious criteria hospitalization and GSK medically significant), respiratory failure (serious criteria hospitalization and GSK medically significant), pneumonia (serious criteria hospitalization and GSK medically significant) and shortness of breath (serious criteria hospitalization). On an unknown date, the outcome of the metapneumovirus infection, respiratory failure, pneumonia and shortness of breath were unknown. The reporter considered the metapneumovirus infection, respiratory failure, pneumonia and shortness of breath to be related to Influenza vaccine Quadrivalent unspecified season. Additional information was provided. This case was reported in a literature article and described the occurrence of human metapneumovirus (MPV) infection in an elderly patient of unspecified gender who was vaccinated with unspecified influenza vaccine (manufacturer unknown). The patient had unspecified significant comorbidities. The patient did not report any sick contacts. No information on patient's family history or concomitant medication was provided. On an unspecified date, the patient received unspecified influenza vaccine (administration route and site unspecified; dosages unknown; batch number not provided). On an unspecified date, an unknown period after vaccination, the patient presented to the hospital with shortness of breath and clinical evidence of pneumonia. The patient's white cell count was elevated with a left shift in differential count (range and normal value not provided). There was confirmatory evidence on chest X-ray in the form of infiltrates. [In this study, 3 out of the 4 patients received a CT scan of the chest confirming extensive bilateral infiltrates and evidence of pulmonary oedema suggesting acute respiratory distress syndrome (ARDS)].The patient required mechanical ventilation and extracorporeal membrane oxygenation (ECMO). The patient successfully weaned off the ECMO, but needed a tracheostomy due to inability to be weaned off the ventilator. It was reported that the patient had evidence of pneumonia with evidence of respiratory failure, and a rapid respiratory viral panel that confirmed MPV infection. This case has been considered serious due to hospitalisation. In this study, the treatment strategy included supportive therapy and broad spectrum antibiotic coverage to counter superimposed bacterial infection. The outcome of the event was unknown. It was reported that the patient survived the disease. The authors did not comment on the relationship between MPV infection and unspecified influenza vaccine. The authors concluded that "The disease spectrum of MPV can vary widely, and the outcomes vary largely based on comorbidities. The infection can frequently lead to severe respiratory failure, progressing to ARDS and death, in the elderly or debilitated patients." This is 1 of the 2 valid cases in the same literature article.