As announced on 10 August, the world is now in the post-pandemic period. Based on knowledge about past pandemics, the H1N1 virus is expected to continue to circulate as a seasonal virus for some years to come. While the level of concern is now greatly diminished, vigilance on the part of national health authorities remains important. Such vigilance is especially critical in the immediate post-pandemic period, when the behaviour of the H1N1 virus as a seasonal virus cannot be reliably predicted.