RESUMEN
Background H5N1 influenza is a cause of severe pneumonia. Co-infection with influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may lead to poor prognosis in the epidemic of COVID-19. However, few studies have reported regarding patients co-infected with avian influenza and SARS-CoV-2. Case presentation A 52-year-old woman presented with fever for eight days and worsening shortness of breath and decreased blood pressure. Computed tomography (CT) revealed air bronchogram, lung consolidation and bilateral pleural effusion. Furthermore, polymerase chain reaction (PCR) of the bronchoalveolar lavage fluid (BALF) showed positivity for H5N1 and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Conclusion H5N1 influenza is a cause of severe pneumonia. The clinical presentation of the patient had a predomination of H5N1 influenza rather than COVID-19. A viral PCR analysis is necessary to demonstrate the pathogen of severe pneumonia. The patient exhibited an excellent prognosis upon the appropriate use of antiviral medicine.