World Health Organisation chief Margaret Chan said on Tuesday that it was too early to declare victory over swine flu and insisted that measures taken to deal with the pandemic were justified. I think that we must remain prudent and observe the evolution of the pandemic over the next six to 12 months before declaring victory, she told Swiss newspaper Le Temps in an interview. Even though the peak of the flu has passed in some countries of the northern hemisphere,such as Canada and the United States,others countries were far from seeing the end,she noted. Winter is still long, said the WHO director-general,adding that a precise picture of the flus impact would not be seen before two years. The A (H1N1) virus has killed at least 11,516 people since it was first detected in March. The rapid spread of the bug led the WHO to declare a pandemic in June. However,with most patients showing mild symptoms,the UN agency has been criticised by some for having over-reacted. Chan defended the WHOs decision to declare a pandemic,saying that the UN agency adopted a very prudent attitude on the issue. I would never have declared a pandemic if I did not have the certainty of proof pointing in this direction, she said. The WHO chief added that the agency took into account advice from independent and impartial experts.