Viral identification
For the identification of PIV l, PIV 2, PIV 3, RSV and ADV , samples were observed under Olympus BX43 LED fluorescence microscope after direct immunofluorescence staining. Samples were considered qualified only when the number of epithelial cells was more than 20, which was judged by at least 2 epithelial cells in each random field at 200× magnification. When more than 2 green fluorescent cells were found in visual field, the samples were judged to be positive. When samples were tested for Flu A and F1u B by colloidal gold method, the quality control line should appear regardless of whether a test line appears, and the result was judged to be positive if the test line appeared.