Finally, we evaluated the activity and inhibitory quotient (IQ) of TCAD against susceptible and resistant viruses representing the currently circulating strains. While the correlation between IQ and clinical efficacy has not been demonstrated for influenza, it is valuable to construct a relative ranking of the IQ of different antiviral regimens against susceptible and resistant viruses in order to assess the spectrum of their activity. When tested against a seasonal susceptible H1N1 virus, an amantadine-resistant 2009 H1N1, and a seasonal oseltamivir-resistant H1N1 virus, TCAD was uniformly active against all three viruses with significantly high IQs (8.33 to 17.24; Table 4 ). This suggests that TCAD may have broad antiviral activity against all currently circulating influenza strains and may have good efficacy in the clinical setting against these strains.