Introduction
A new acute respiratory disease reported in last winter named coronavirus disease 2019 (COVID-19), was found to be caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It was revealed that SARS-COV-2 virus felled within the subgenus Sarbecovirus of the genus Betacoronavirus , with about 79% identity to SARS-COV and sharing a similar receptor-binding domain structure to that of SARS-COV, despite a little difference in some residues (Lu et al.2020).This virus now has swept the world with a stunning speed and brought tremendous pressure to the medical system. Many studies had descripted the clinical characteristics and radiological changes of COVID-19. The most common symptoms of COVID-19 were fever and cough (Huang et al, 2020;Wang et al, 2020), and the most representative images of computed tomography were peripheral ground-glass opacities (Chung et al, 2020;Zhang et al, 2020).
Influenza A viruses (IAV) belong to the Orthomyxoviridae family and are further divided into subtypes according to the two surface glycoproteins, haemagglutinin and neuraminidase. IAV can cause acute respiratory illnesses which usually occur in winter seasons periodically and often cause severe illnesses and economic loss around the world (Lafond et al, 2016;Thompson, 2004). Depending on the features of host and virus, patients got infected with IAV could present different symptoms, including fever, chills, myalgia and respiratory symptoms such as dry cough, nasal tampon, etc. The typical changes in chest radiology images of IAV patients were ground-glass opacities and consolidation (Collins et al, 2019;Sargın et al, 2018).
In clinic, co-infection can happen in viral-bacterial and viral-viral infection during the influenza season and cause more severe clinical conditions (Martin-Loeches et al, 2017;McCullers, 2006). We also find some patients were infected with both SARS-COV-2 and IAV in the COVID-19 pandemic (Ding, Lu, Fan, Xia, & Liu 2020;Khodamoradi, Moghadami, & Lotfi, 2020;Wu et al, 2020). Due to the scattered cases, we do not have a profile knowledge about the course of those co-infected patients. It deserves more attention to those patients who suffers from co-infection with SARS-CoV-2 and IAV. Herein we reviewed some published studies and described a cohort of patients co-infected with SARS-CoV-2 and IAV in the COVID-19 pandemic, aiming to explore more knowledge about COVID-19.