Retrospective detection reveals absence of SARS-CoV-2 infection in human throat swab samples collected during Jan-May 2019 in the influenza epidemic season

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) are three emerging coronaviruses with huge public health in the 21st century. Especially, SARS-CoV-2 causes an unprecedented global pandemic and has spread in over than 200 countries. Clinically, SARS-CoV-2 could co-infected with respiratory pathogens including influenza virus and adenovirus in some present cases. This suggests that the differential diagnosis cannot be ignored. To investigate whether SARS-CoV-2 exists earlier and identify possible co-infection in human with respiratory disease, we performed the detections of SARS-CoV-2 and influenza virus using real-time RT-PCR method and colloidal gold test strip in 534 throat swab samples collected in influenza epidemic season (from January to May of 2019). 336 samples (62.9%) were tested positive for influenza virus, which involved into 230 single influenza A virus (IAV)-positive samples, 4 single influenza B virus (IBV)-positive samples, and 102 IAV and IBV co-infection samples. Unfortunately, we found no positive signal of SARS-CoV-2 in 534 samples. Our finding reveals absence of SARS-CoV-2 infection in human archived samples in before the outbreak of SARS-CoV-2 in China. In addition, this study suggests that IAV was still major respiratory pathogen responsible for respiratory disease in the influenza season.