Passage: Influenza produces direct costs due to lost productivity and associated medical treatment, as well as indirect costs of preventative measures. In the United States, seasonal influenza is estimated to result in a total average annual economic cost of over $11 billion, with direct medical costs estimated to be over $3 billion annually. It has been estimated that a future pandemic could cause hundreds of billions of dollars in direct and indirect costs. However, the economic impacts of past pandemics have not been intensively studied, and some authors have suggested that the Spanish influenza actually had a positive long-term effect on per-capita income growth, despite a large reduction in the working population and severe short-term depressive effects. Other studies have attempted to predict the costs of a pandemic as serious as the 1918 Spanish flu on the U.S. economy, where 30% of all workers became ill, and 2.5% were killed. A 30% sickness rate and a three-week length of illness would decrease the gross domestic product by 5%. Additional costs would come from medical treatment of 18 million to 45 million people, and total economic costs would be approximately $700 billion.Preventative costs are also high. Governments worldwide have spent billions of U.S. dollars preparing and planning for a potential H5N1 avian influenza pandemic, with costs associated with purchasing drugs and vaccines as well as developing disaster drills and strategies for improved border controls. On 1 November 2005, United States President George W. Bush unveiled the National Strategy to Safeguard Against the Danger of Pandemic Influenza backed by a request to Congress for $7.1 billion to begin implementing the plan. Internationally, on 18 January 2006, donor nations pledged US$2 billion to combat bird flu at the two-day International Pledging Conference on Avian and Human Influenza held in China.In an assessment of the 2009 H1N1 pandemic on selected countries in the Southern Hemisphere, data suggest that all countries experienced some...

Question: What direct cost does influenza incur?
lost productivity and associated medical treatment