rtPCR for respiratory viruses was performed on 328 respiratory specimens, of which 74 samples were excluded due to insufficient clinical information or repeated testing of separate specimens for respiratory viruses in the same patient within 3 weeks. Data on 254 patients were analyzed, including 11 sputa, 47 nasopharyngeal swabs, 63 nasopharyngeal aspirates, 123 bronchoalveolar lavages, 9 tracheal aspirates and 1 pleural effusion.