| Background Influenza is a viral respiratory infection that occurs almost every year worldwide as local outbreaks or as widespread pandemics. Treatment of infectious disease is one of the major areas of study in CM based on the Chinese theory of wen bing, meaning “feverish disease”. The similarities in manifestations of symptoms of wen bing with that of viral infections in modern medicine has led to classifying all kinds of flu-like diseases, including Avian flu ad SARS, into the category of wen bing under CM practice. Yin Qiao and Sang Jiu Yin (YS) is a combined formula of two traditional Chinese Medicine (CM) formulae recommended by the Ministry of Health, China for treatment of influenza-like illnesses. There has been no formal clinical trial of YS, however, YS have been used for thousands of years by CM practitioners. Study Objectives 1) To evaluate the efficacy of Yin Qiao San and Sang Jiu Yin in treatment of naturally acquired influenza infection as measured by time to alleviation of influenza symptoms as the primary efficacy measure; 2) To evaluate the safety of Yin Qiao San and Sang Jiu Yin in treatment of naturally acquired infection. |