Before effective vaccines become available, antiviral drugs are considered as the major control strategies for a pandemic influenza. However, perhaps such control strategies can be severely hindered by the low-efficacy of antiviral drugs. For this reason, using antiviral drugs and an isolation strategy is included in our study. A compartmental model that allows for imported exposed individuals and asymptomatic cases is used to evaluate the effectiveness of control strategies via antiviral prophylaxis and isolation. Simulations show that isolation strategy plays a prominent role in containing transmission when antiviral drugs are not effective enough. Moreover, relatively few infected individuals need to be isolated per day. Because the accurate calculations of the needed numbers of antiviral drugs and the isolated infected are not easily available, we give two simple expressions approximating these numbers. We also derive an estimation for the total cost of these intervention strategies. These estimations obtained by a simple method provide a useful reference for the management department about the epidemic preparedness plans.