CD40LG and viral infectious disease: After that, the potential protective effects influenza virus IgM positive in severe COVID-19 patients were observed If patients are suspected ILI, especially suffering from virus infection, a prompt test, like a one-time diagnostic panel for the respiratory virus nucleic acid, antigen or serological detection of virus specific IgM/ IgG, should be the first step with an expanded detectable rang towards confirming diagnosis, which help in making early and effective prevention and treatment strategy.