The Trust for America's Health projected a $683 billion economic loss nationally during a pandemic, which is about 5.5 percent of the goods and services produced in the United States. The number is comparable to a previous analysis conducted for Congress, but the latest report is the first to break down the impact by state.

Nevada's economy could take a hit of more than 8 percent, while Hawai'i's economic output could fall by about 6.6 percent. Four other states — Alaska, Wyoming, Nebraska and Louisiana — also stand to take hits of greater than 6 percent in their gross domestic product.

"In a pandemic, we will see people avoiding discretionary travel and avoiding large gatherings for the legitimate fear of contagion," said Jeffrey Levi, executive director of Trust for America's Health. "It's a natural reaction not to want to be in large groups when there is an easily transmittable disease afoot."

Trust for America's Health conducts research and advocates for steps it believes improves public health.

Sen. Majority Leader Harry Reid, D-Nev., said the report underscored the importance of investing in preparedness.

"Senate Democrats have fought to ensure our country is prepared and I will do what I can to increase our investment in this vital area," Reid said.

There have been three pandemics during the past century in the United States. A pandemic comparable to the most serious — in 1918— could sicken 90 million people and kill about 2 million. It could also last up to 18 months with spikes that last six to eight weeks each.

Trust for America's Health considered how a severe pandemic would impact consumer demand for products and services. For instance, tourism and entertainment could experience an 80 percent decline in demand. A comparable decline could occur for hotels and restaurants.

Meanwhile, the transportation and warehousing sectors could experience a 67 percent decline in demand. Those industries are particularly important for Alaska, Nebraska and Wyoming.

The organization predicted that the economies of Virginia and Maryland would fare the best among the states but still face significant declines of 5.13 percent and 5.06 percent, respectively. Washington, D.C., could face a 4.62 percent decline.

Levi said economies that rely more on the government tend to be more stable under any kind of economic stress. Even though a lot of people won't work, many government workers would continue to get paid. Often, the private sector is not able to absorb that expense, he said.

"In a crisis, the government tends to ramp up its spending," Levi said.

Other sectors of the economy that could see a limited fall in demand would be the financial and insurance industries, as well as the agriculture and mining industries. The demand for those industries would drop about 10 percent, said the report, which cites the Congressional Budget Office for the estimate.

Demand for healthcare and social services would go up 15 percent. No change in demand is projected for waste services, government and the real estate industry.

Levi's organization, which conducts research and advocates for steps it believes improves public health, says that stepping up preparedness planning is vital to the nation's economic security.

Efforts so far have focused on enhancing public health capabilities, but efforts to prepare for the economic ramifications have been inadequate, the organization contends.

On the Web: