2nd H1N1 (swine flu) shot?

For the very young and some of the elderly, the immune system can be slow to recognize the flu vaccine, so there is a need for a 2nd to act as a booster. There is really no way to know if the first shot has awaken the immune system and therefore is enough. This is why a second one is needed to be certain. You child may be partially protected, but you should get the 2nd shot as soon as it becomes available just to be safe.