The decision to reopen the sites reflects a deeper understanding of the virus and its potential to spread quickly beyond schools.
"It is no longer necessary to keep schools closed," said John M. Colmers, state secretary of health and mental hygiene. But he cautioned that the flu was likely to spread through the general public and that students and staff should stay home for seven days if they have a cough and fever.
"You have to weigh the educational needs of the students as well as their safety, and we are going to err on the side of safety," Colmers said.
The CDC decision announced during a briefing to reporters Tuesday afternoon reverses recommendations made last week that resulted in hundreds of school closures nationwide, including those in four Maryland school districts.
"The change in the school closing guidance reflects our understanding in what we know of transmission and severity," said Dr. Richard E. Besser, the CDC's acting director. "This does not change personal responsibility, in terms of hand washing ... and staying home if you are sick."
Montgomery County was the first to announce that it would reopen the only school in its district that had been closed: Rockville High School. Schools chief Jerry Weast, who had sparred with state health officials Monday afternoon over the issue of whether to keep the school closed another day, had his office release the news about an hour after the CDC sent out new guidance.
"It is the right decision and the right thing to do," Weast said. The superintendent said he supported the decision to close schools last week, but as time went on he said he began to question the decision because states took different views on whether to close. He said no schools closed in Virginia, for instance.
The new CDC guidelines are "very clear and coherent," he said. "If you are going to deprive a child of an educational opportunity, there had to be a reason that this flu was different from any other flu or MRSA."
Besser said officials originally hoped closing schools would keep the virus from spreading. He added that there was much that health officials and scientists did not know when they made their recommendation last week that schools with probable swine flu cases should close for 14 days.
But with 1,100 probable and confirmed cases and two deaths in the United States - and projections that those figures will swell - closing schools isn't effective.
"We know that in communities that are seeing cases in the school, they're already seeing cases in the communities," said Besser. "So a strategy of trying to stop the transmission by approaching it as a school phenomenon is not very appropriate."
Besser acknowledged the hardship schools and parents face when schools close suddenly and said officials weighed those worries against public health concerns when revising their recommendations.
"When we hear of the difficulty involved of children who are dropped at libraries because there's nowhere for home care, of people who could lose their jobs because they don't have sick leave, these factors are really real," he said.
There have been no deaths in Maryland and no hospitalizations. Nationwide, the virus appears no more serious than a seasonal flu, which would not normally close schools.
In addition to Rockville High, the schools that will reopen today are: Milford Mill Academy in Baltimore County, Folger McKinsey Elementary in Anne Arundel County, and Montpelier, University Park and Vansville elementaries in Prince George's County.