For years the UK's health professionals have been preparing for a pandemic flu outbreak that they fear could lead to huge numbers of deaths and seriously disrupt the functioning of the nation.
But major organisational changes in Northern Ireland health care provisions came into place on 1 April 2009, just weeks before the outbreak of the pandemic.
Yet Chan reiterated the WHO's recommendation not to close borders or restrict trade in response to the outbreak, saying the world "is better prepared for an influenza pandemic than at any time" in history.