Fifteen states could run out of hospital beds and 12 more could fill 75 percent of their beds with swine flu sufferers if 35 percent of Americans catch the virus in coming weeks, a report released Thursday said.

The study, based on estimates from a computer model developed by the U.S. Centers for Disease Control and Prevention, shows the strain hospitals and health departments could face as a second wave of swine flu surges.

Our point in doing this is not to cry Chicken Little but really to point out the potential even a mild pandemic can have and how readily that can overwhelm the healthcare delivery system, Jeffrey Levi, director of Trust for America's Health, which sponsored the report, said in a telephone briefing.

According to the report, the number of people hospitalized could range from 168,025 in California to 2,485 in Wyoming, and many states may face shortages of beds.

Some may need to cut back on hospitalizations for elective procedures.

States around the country will also have to figure out how to manage the influx of people in doctors' offices and ambulatory care settings, in addition to the surge in hospitalizations, Levi said.

He said state and local health departments are scrambling to set up distribution systems for the H1N1 vaccine as it becomes available this month, but challenges remained.

These systems are untested, and glitches are sure to arise along the way, Levi said.

Local health authorities are especially worried about reaching young people, who traditionally are not vaccinated for flu, and minorities, who were harder hit by the swine flu in the spring.

While the federal government will pay for the vaccine itself, Levi said, it was not yet clear how the actual cost of giving the shot will be financed.

Although many public and private insurance plans have said they will cover it, others have not yet agreed.

This could become a huge burden for state and local health departments, or become a dangerous disincentive for people to get a vaccine, he said.

The 35 percent attack rate used in the report is based on the 1968 flu pandemic, which was considered mild. It assumes an outbreak would last around eight weeks.

Levi said the number was consistent with World Health Organization statements predicting that up to a third of the world's population will become sick with the new H1N1 virus that was declared a pandemic in June.

The President's Council of Advisors on Science and Technology said in August that 1,8 million Americans may need to be hospitalized and around 30,000 could die, assuming a 30 percent infection rate.