BOSTON -- Nearly 100,000 people could die from the H1N1 influenza virus this flu season, according to national health officials.

The report by a presidential panel of the nation's top scientists predicts that up to half of Americans will get the H1N1 virus by winter, 2 million will be hospitalized and 30,000 to 90,000 will die -- mainly children and young adults.

"The best thing that we can accurately predict about what is going to happen next is that we need to expect the unpredictable," said Health and Human Services Secretary Kathleen Sebelius.

A vaccine could ease fears and contain the virus, but roughly 50 million doses of the vaccine are not expected until mid-October when the H1N1 virus could be at its peak.

With clinical trials beginning this month, some public health experts are worried.

"Trying to rush in with an unknown, with an untested quantity of vaccine doesn't appeal to me at all," said Dr. William Schaffner, of Vanderbilt University.

Next week, the number of H1N1 cases is expected to multiply partly because of the start of the academic year. Local school systems said they are all ready planning for flu season.

"The virus only spreads by live wet droplets, something that if a child sneezed on a desk, certainly it could be communicated to somebody right away," said Revere Public Schools Superintendent Dr. Paul Dakin.

Last spring, absenteeism in Revere schools ran as high as 28 percent. This fall, in addition to strict cough etiquette and hygiene, like hand washing and sanitizing, the city's 6,100 students will be separated to minimize possible exposure and infection.

"Small groups, don't mingle kids. Instead of moving kids to class to class, we will move the teachers from class to class. Places were there might have been four gym classes at once, we separated them in a big gym, separate them and not have everybody in the gym at once," Dakin said.

The seasonal flu causes an estimated 250,000 hospitalizations and 36,000 deaths nationally each year. Certain groups of people are at higher risk of complications from the flu. These groups include: children younger than 2, adults older than 65, pregnant women, and people with chronic health conditions such as asthma, diabetes and heart disease. These people should call their doctor immediately to discuss appropriate treatment if they develop a fever with a cough, sore throat or runny nose.