Department of Health and Human Services Secretary Tommy G. Thompson unveiled a large-scale plan Wednesday for national, state and local policy makers and health departments to respond effectively to an unlikely influenza pandemic.

The “Pandemic Influenza Response and Preparedness Plan” is a “roadmap” for key leaders. It describes coordination and decision making at the national level; provides an overview of key issues; and outlines action steps that should be taken at the national, state and local levels before and during a pandemic.

Pandemics are rare, the report says, but such a virus would be unaffected by the nation’s current flu vaccines because it’s a major, sudden shift in the virus’ structure.

Three influenza pandemics occurred during the 20th century, the most recent in 1968 with the Hong Kong flu outbreak, which contributed to nearly 34,000 deaths in the United States. In 1957, the Asian flu pandemic contributed to about 70,000 deaths. The 1918 Spanish flu pandemic devastated the world, affecting roughly 20% to 40% of the world’s population and more than 50 million deaths worldwide.

The draft plan can be found at www.hhs.gov/nvpo/pandemicplan and is available for public comment for 60 days.