School nurses nationwide may see far more than the usual number of students this fall and teachers may see an above-average share of empty seats. The reason, as you've surely heard, is a strong flu strain that doctors call H1N1 and that originally was called swine flu. It has spread around the country since April, infecting more than 1 million Americans -- including more than 5,000 admitted to hospitals. U.S. fatalities exceed 520.

Public health officials now fear a severe epidemic during fall's customary flu season, when schools and colleges face particular jeopardy because students are in close contact each weekday. Federal researchers and drug companies are scrambling to develop and distribute a specialized vaccine aimed solely at H1N1. Still undergoing clinical trials, it's expected to be available by mid-October -- and sooner for high-risk people such as the elderly and chronically ill. (Regular seasonal flu shots still are recommended.)

School districts across the country stress preventive steps -- hand-washing, shielding sneezes and coughs -- and plan for building shutdowns. In addition, janitors and other staff members are sanitizing doors, handrails, fountains and sinks more often in an effort to limit the spread of any virus. The federal Centers for Disease Control started a "Keep 'em Home!" campaign urging parents not to send sniffling, coughing pupils to school.
To inform students and adults about the risks, precautions and need for vaccination, the CDC is using Facebook (CDC fan page), MySpace (cdc_ehealth) and Twitter (@FluGov). It also posts videos, such as the one below, about the importance of hand-washing.

Doctor warns: "A lot of people are going to be infected." -- Dr. Harold Varmus, co-chair of presidential Council of Advisors on Science and Technology

School superintendent says: "We basically need cooperation from the families. I can't tell you how important it's going to be if the children are sick and exhibiting flu-like symptoms, not to send them to school." -- Supt. Chuck Suppon, Wyoming Valley West School District in Kingston, Pa.

Campus official says: "We are all learning how quickly it spreads. What we've got to do is deal with the reality of having a lot of sick people." -- Bronson Hilliard, University of Colorado-Boulder spokesman