Antiviral drugs dispensed during the 2009 influenza pandemic generally failed to contain transmission. This poses the question of whether preparedness for a future pandemic should include plans to use antiviral drugs to mitigate transmission. The threat from avian influenza H1N5 prompted many countries to establish a stockpile of antiviral drugs,such as oseltamivir and zananivir. The size of the antiviral stockpile and its proposed use, therapy or prophylaxis, were keenly debated during the preparation of pandemic management plans. The emergence of pandemic H1N1 in 2009 prompted a variety of strategies for the use of antiviral drugs and motivates this look at the use of antiviral drugs for prophylaxis and implications for decisions on the size of an antiviral stockpile for a future pandemic.