The 2009 Influenza Pandemic: An Overview

On June 11, 2009, in response to the global spread of a new strain of H1N1 influenza flu, the World Health Organization WHO declared the outbreak to be an influenza pandemic, the first since 1968. WHO said that the pandemic declaration was based on the geographic spread of the new virus, not on increasing severity of the illnesses it causes. Officials now believe the outbreak began in Mexico in March, or perhaps earlier. The novel H1N1 swine flu was first identified in California in late April. Health officials quickly linked the new virus to many of the illnesses in Mexico. Since then, cases have been reported around the world. U.S. health officials continue to monitor the situation, noting that the efficiency of viral transmission and the severity of illness could change in the fall, as the Northern Hemisphere winter approaches. Anticipating that a vaccine against the pandemic strain is to become available, officials say they would decide whether to recommend the vaccine for civilian use. In that case, federal, state and local officials would face decisions regarding the distribution of the vaccine, and about how best to prioritize the allocation of limited supplies. This report first provides a synopsis of key events, actions taken, and authorities invoked by WHO, the U.S. federal government, and state and local governments. It then discusses the WHO process to determine the phase of a flu pandemic, selected activities by the Departments of Homeland Security and Health and Human Services, and selected activities by state and local authorities. Next, it lists congressional hearings held to date, and provides information about appropriations and funding for pandemic flu activities. Finally, it summarizes U.S. government pandemic flu planning documents and lists sources for additional information about the situation. This report will be continually updated to reflect unfolding events.