The Department of Education closed a Manhattan school Wednesday out of concerns over the H1N1 flu virus, as nine schools in Queens, Bronx and Brooklyn that were previously closed to stop the spread of the disease reopened.

P.S. 161 in Morningside Heights is the latest school to join the list of closed schools, but Mayor Michael Bloomberg admitted today that he was not sure whether closing schools actually helps prevent the spread of illness.

"Nobody knows. It's not one of these things," said the mayor. "I've said this before, the professionals when you ask them say if you close all the schools for a month there's no evidence that it would make any difference."

Among the reopened schools was Q499 in Queens, which had been closed due to fears over the spread of the H1N1 virus. The school had been closed since Friday. It also houses P993.

Many teachers, parents, and students were happy the school is open again.

"I'm perfectly comfortable with all of my children, all my staff," said teacher Fred Liebowitz. "I love my kids and I'm very happy to be back at school."

"I'm going to bring him in just like a pilot deal," said parent Rafael Castillo. "If he comes home and half his class comes out, or I see any signs, I'm going to home school him for the rest of the month."

"I'm feeling safe because most of the kids are still not coming back," said a student. "I've been talking to them. They say they're not coming back because they're still kind of sick."

Though one student's parents chose to send her to school with a surgical mask, other parents said they were mostly fine with bringing their children to school.

"They didn't get sick last week, and they were here every day until they closed the school, so I want to say hopefully they're okay," said parent Dehlia Holmes.

"It does make me nervous and anxious, but I'm just around the corner today, so we'll be fine," said Alexandra Contreras, another parent.

Rafael Castillo said he will keep a close eye on the situation with his son Aaron.

"I'm going to bring him in for like a pilot program," Castillo said. "If he comes home and half his class is still out, and I see any signs, I'm going to home school him for the rest of the month."

On Tuesday, health officials announced that Special Education School 811Q, located in Building 822Q in Saint Albans, would be closed starting today, along with P.S. 128 in Washington Heights, 231 K in Bensonhurst, P.S. 68 in Wakefield, and 369K in Boerum Hill.

Officials stress the schools are closing as a precaution because of a high number of students with flu symptoms. There are no confirmed swine flu cases at the schools.

Meanwhile, health officials are waiting for the autopsy results of two residents who died after testing positive for the flu strain.

A 41-year-old woman from Queens and a 34-year old man from Brooklyn had the virus, but both also had other health issues that made them less able to deal with a case of the flu.

City officials have not commented on what the conditions were, but sources tell NY1 they had to do with either the heart or lungs.

"Every death we've had in New York City and until now every case of severe illness we've documented has been in someone with an underlying condition," said outgoing Health Commissioner Thomas Frieden. "That means if you have asthma, diabetes, heart disease and you get a fever, see your doctor immediately. The quicker you get treated for possible H1N1 flu, the more likely you are to do better."

In New Jersey, the number of confirmed H1N1 cases has nearly doubled since last week – bringing the total number to 56.

Of the state's 21 counties, 11 have reported cases of swine flu.

Officials say those infected range from ages 8 months to 55 years old.

So far, no deaths have been reported.