Dec 17, 2009 10:36 AM by NBC
Data are in from three big studies of the H1N1 swine flu vaccine -- researchers say adults had at least 95-percent immunity to the swine flu virus after just one dose.
Kids under 10 had a lower immune response after one dose -- suggesting they need two, just as the experts recommend.
Researchers also found both the seasonal and H1N1 flu shots were safe, including when given at the same time.
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