NEW YORK, NY November 06, 2009 —Less than a quarter of the city's elementary school children returned parental consent forms to get swine flu vaccines. City health officials say about 5,500 students took advantage of the free, in-school vaccination program. Mayor Bloomberg says he's surprised.

BLOOMBERG: I had no reason to know what it would be. I'm disappointed, I think is fair. The best experts say you should do that.

REPORTER: The mayor says the low response may be partly due to the fact that the city hasn't experienced a repeat of the swine flu epidemic from spring. The health department says the low vaccination rates don't account for children who got shots from their pediatricians.