WHO Declares H1N1 Pandemic

June 11, 2009 — 

The World Health Organization (WHO) has issued a pandemic declaration following the global emergence of a novel influenza A virus in the human population.

Based on consultations with expert assessments of the available evidence, the organization has raised the pandemic alert from 5 to 6, its highest level, signaling the official start of the 2009 influenza pandemic. Current evidence indicates that the pandemic, at least in its early days, will likely be of moderate severity with the overwhelming majority of patients experiencing mild symptoms followed by a rapid and full recovery, often in the absence of any form of medical treatment. The organization does not anticipate a dramatic increase in the number of severe or fatal infections but expresses concern that the severity may increase as the disease moves into countries with limited resources, poor health care and a high prevalence of underlying medical problems.

The WHO recognizes that this novel virus preferentially infects younger people with the majority of cases in people under 25 years of age. In some countries, approximately 2% of the cases have progressed to severe illness with most cases of severe and fatal infections occurring in adults between the ages of 30 and 50. This pattern of infection, along with the continued circulation into the warmer weather, differentiate this viral presentation from that of the more common seasonal influenza. The WHO estimates that one third to one half of the severe and fatal infections have occurred in previously healthy young and middle-aged people.

Source: The World Health Organization, Press Release June 11, 2009