This change from a muzzling institute to a university that was not familiar with 'ministerial responsibility' liberated him in his role as public expert; and with this change a second came along: he became director of the WHO National Influenza Centre. Influenza appeared on his radar screen and Osterhaus became interested in past influenza pandemics. He then became chairman of the European Scientific Working group on Influenza, the ESWI. On a more personal note, being struck by influenza himself made him experience the severity of flu. These personal, professional and scientific experiences with flu would from now on become a dominant factor in his contact with policy and the media (Osterhaus 29 July 2008). In 1995, he made some initial, cautious remarks that hinted at the lurking threat of influenza (Trouw 17 February 1995) . But in 1997 the cautiousness gave way to a much more alarming message when the first human bird flu casualty was reported (Osterhaus 6 March 2008). Osterhaus and others wrote a letter to Nature entitled A Pandemic Warning (De Jong et al. 1997) , in which they referred to H5N1 as a virus with 'unknown pandemic potential'. A few months later he would be more straightforward in a Dutch newspaper, saying that 'a future pandemic flu on the scale of the 1918 Spanish Flu was not unimaginable' (Algemeen Dagblad 30 December 1997) .