Associated Press: Health investigators are trying to figure out why swine flu has spread erratically -- moving quickly through a few schools but slowly elsewhere -- after an outbreak closed three more New York schools.
The decision on Thursday to shutter the schools follows an outbreak that left an assistant principal in critical condition and sent hundreds of kids home with flu symptoms, in a flare-up of the virus that sent shock waves through the world last month.
Schools are a good incubator for illness in general because space is tight and youngsters often don't practice the best hygiene, said Dr. Isaac Weisfuse, a deputy commissioner of the health department.
Across the country, most of the people getting the illness have been young. Some experts have speculated that older people might have some immunity to the virus because of genetic similarities to more common types of flu.
"We're trying to answer some of those questions," Weisfuse said.
Mayor Michael Bloomberg said four students and the assistant principal have documented cases of swine flu at a Queens middle school. More than 50 students have gone home sick with flulike symptoms, he said. At another middle school in Queens, 241 students were absent Thursday. Dozens more were sick at an elementary school.
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