Pandemic officially a year old Today marks the passage of a year since the World Health Organization (WHO) declared a pandemic of H1N1 influenza. WHO Director Margaret Chan declared phase 6 on Jun 11, 2009, about 7 weeks after the virus had surfaced. The WHO hesitated to take the step because of concern that it would cause undue alarm, given that H5N1 avian flu had led the public to associate "pandemic" with high death rates.