WASHINGTON — The government is giving schools new guidance to follow when swine flu strikes, in hopes of preventing the panic and confusion that prompted hundreds of school closures last spring.

Swine flu is expected to return after school starts this fall. Unlike regular seasonal flu, this virus has not died out during the hot and humid summer months and so far has infected more than 1 million Americans.

Federal officials plan to issue new guidelines for school closings today. The decision to close actually rests with local school officials. But those officials are looking to the federal government for advice about the new flu strain that has caused a global epidemic, or pandemic.

“The judgment will always have to be made at the local level,” Education Secretary Arne Duncan said Tuesday during a forum with administration officials that was broadcast online.

“What we want to do is empower the local governments … to make the right decision,” he said.

The administration wants to avoid the chaos of last spring, when more than 700 schools in half the states closed their doors (there are about 132,000 public and private schools in the U.S.). Students got an unexpected vacation, but many parents wound up scrambling to find child care.

School officials were acting on advice from the federal Centers for Disease Control and Prevention, which at first said that schools should shut down for about two weeks if there were suspected cases of swine flu.

Then the CDC changed course, saying schools did not need to close, because the virus was milder than feared. Instead, parents were told to keep sick kids home for at least a week.

Duncan said at a swine flu summit last month that closing school should be “a last resort, not a first resort.”

He said Tuesday that districts should use common sense. “If you have one child sick, that’s one thing. If you have a whole host of children getting sick, that’s another,” Duncan said.

While this particular flu virus is new, the matter of school closings is not. Every winter, regular flu outbreaks prompt a relatively small number of schools to close for a few days because of high absenteeism among students or staff.

In addition to new guidance for when to close, the CDC and Education Department said this week they have set up a new monitoring system to track school closures across the country.

Still up in the air is whether schools will be turned into vaccine clinics, though Health and Human Services Secretary Kathleen Sebelius has said that seems logical. “We’re seeing schools as potential partners,” she said during Tuesday’s forum.

Children are on the priority list for the first doses of swine flu vaccine, but because of time needed for testing and manufacturing, inoculations can’t begin until school has been in session for more than a month; the government is aiming for Oct. 15.