When the H1N1 flu strain first appeared in the U.S. this spring, hundreds of schools closed their doors and sent students home, alarmed over the potential for contagion that occurs when you bring together a large group of people — and not-always-hygienic people, at that. This fall, schools are being more pragmatic.

Based on advice from the Centers for Disease Control and Prevention, schools are planning to remain open in the almost certain face of widespread flu outbreaks.

Question: Are children particularly vulnerable to the virus?

Answer: Young people are particularly susceptible to contracting the virus for unknown reasons, possibly because of a lack of immunity and because of lax hand-washing habits. The spread of the flu among children and young adults can be hastened because of their proximity to others in classrooms, camps, dorms and similar large gathering spots. Overnight camps were particularly hard-hit with flu cases this summer, prompting some to send children home.

Q. Are school outbreaks expected this fall?

A. Federal, state and local health and education officials say it is a near certainty that there will be an increase in the number of flu outbreaks now that school is open, and that children could pass the virus to their families and other members of their community.

Q. What are school officials doing to protect children?

A. Many schools and classrooms are being stocked with soap, hand sanitizer, paper towels and tissues, and administrators are sending home letters to parents outlining prevention strategies.

Following guidelines issued by federal, state and county health officials, teachers, nurses and others will stress the importance of hand-washing, and will be on the lookout for students exhibiting flu-like symptoms. Some schools are stepping up routine cleaning, especially for doorknobs, computer keyboards and other frequently touched areas.

If the swine flu strain mutates into something more serious, stricter precautions may be instituted, such as screening children for fever when they arrive at school every morning, avoiding large student gatherings and dismissing students on a staggered schedule.

Q. If a child becomes ill at school, what happens?

A. The child will be isolated from classmates until the parents pick him or her up, according to federal guidelines. Districts are making contingency plans to allow homework and lessons to be delivered to students who are ill, and to allow makeup tests and other classwork once they return to school.

Some institutions plan to notify parents if a classmate becomes ill and children were exposed to the virus.

Q. When can an ill child return to school?

A. After the child is fever-free for 24 hours. Most schools will follow the honor system, but some will require a doctor's note for re-admittance. Parents should check with their schools for specific requirements.

Q. Will schools close if children or staff become ill?

A. More than 700 schools throughout the nation closed in spring because of suspected outbreaks. But the federal government is urging a more conservative approach this fall: Schools should be closed only as a last resort if classes could not continue because so many students or staff are absent. Exceptions are schools that serve vulnerable populations, such as pregnant teenagers or students in fragile health with conditions such as muscular dystrophy.

Q. Who makes decisions about how schools prepare for the flu and whether schools should be closed?

A. School district officials who prepared for swine flu with guidance from county, state and federal health officials make that decision. The decision to close a public or private school because of an outbreak would be made by either the district superintendent or the county health officer.

Q. Should parents keep their children home from sleepovers and other social gatherings on the weekends and after school?

A. Health officials say children should be kept home only if they are ill.

Q. Do private schools, after-school programs or childcare centers have different rules?

A. All institutions are following the guidance provided by the Centers for Disease Control and Prevention, as well as state and county health officials. Some policies vary, such as whether classmates of an ill child are notified. Parents will likely receive information about local policies at the start of the school year, in letters sent home and in back-to-school packets.

Q. Where can parents turn for more information about the virus?

A. More information is at www.flu.gov.