The problem with many people claiming to get sick from their flu shots is that they're idiots. All the people that are getting their flu shots now or during the peak flu season are getting exposed before your body has the time (4 weeks) to build the appropriate antibodies. They in turn get sick because they were exposed before the shot works. You don't become magically immune to the flu the second you recieve the shot...
Those saying the shot only protects against 1 strain are also wrong. There are 3 strains it protects against: A, B and H1N1. But hey, keep spreading misinformation and anecdotes about mercury and ineffectiveness. When you're at home missing work or school I'll be feeling fine and dandy!