A potential vaccine for the swine flu is presently being tested for safety and efficacy. The problem is that it would then need to be manufactured and administered in huge quantities by September. The reason for the September deadline is because, even after being given a flu vaccine, it takes 6-8 weeks for the body to build up its immune system to fight the flu after being given the vaccine. Since the peak flu season is typically from November to January, one can count backwards and figure out that the flu vaccine needs to be administered by September.
