<qa>  What is the sustained viral response rate of combination therapy?Thymosin alpha1interferon combination therapy has been known as an effective antiviral therapy for chronic hepatitis B. It is superior to interferon single therapy since the sustained viral response rate of combination therapy used to be about 70 compared with that of single interferon therapy20. Until now, the combination therapy including 6-month treatment of thymosin alpha1 has been as effective as 12-month treatment of thymosin alpha1. We hypothesized that thymosin alpha1 is an immune potentiator so, the shorter duration of thymosin alpha1 treatment might be as effective as the prolonged treatment duration. 