The 2009 Influenza A(H1N1) "Swine Flu" Outbreak: An Overview

On April 29, 2009, in response to the global spread of a new strain of influenza, the World Health Organization WHO raised its influenza flu pandemic alert level to Phase 5, one level below declaring that a global influenza pandemic was underway. According to WHO, the declaration of Phase 5 is a strong signal that a pandemic is imminent and that the time to finalize the organization, communication, and implementation of the planned mitigation measures is short. The new flu strain was initially dubbed swine flu because it contains genetic material from flu strains that normally circulate in swine. But there has been no evidence to date that pigs are involved in the transmission of this virus to humans. There have been concerns that the term swine flu has had unwarranted trade implications for swine and pork products. On April 30, 2009, WHO began referring to the new strain as influenza AH1N1. On May 2, the Canadian Food Inspection Agency CFIA reported finding the outbreak strain in a swine herd in Alberta, the first time the strain has been identified in swine. Preliminary investigation suggests that the herd was exposed to the virus from a Canadian who had recently returned from Mexico and had been exhibiting flu-like symptoms. This report provides an overview of key actions taken and authorities invoked by WHO and the U.S. government. First, it discusses the WHO process to determine the phase of a threatened or emerging flu pandemic and touches on a number of related issues. The report then examines actions taken by the Departments of Homeland Security and Health and Human Services and provides information about appropriations and funding for pandemic flu activities. Finally, the report summarizes U.S. government pandemic flu planning documents and lists sources for additional information about the situation as it unfolds. This report will be continually updated to reflect unfolding events.