I don't see immunization as impacting liberty, anymore than requiring insurance to drive, seatbelts installed on cars, hospitals with emergency rooms, or guardrails on bridges.
These are all put in place to save lives, freedom doesn't mean a whole lot to you when you are dead. A shot in the arm does not impact your freedom of speech, the pursuit of happiness nor any other right. It is a biological control on preventing a plague from wreaking havoc on us. If not for the polio vaccine how many people would be dead today?
At the height of the polio epidemic in 1952, nearly 60,000 cases with more than 3,000 deaths were reported in the United States alone.
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I like modern science, I'm just an engineer (not a medical expert); but to me it seems silly to reject a vaccine by saying it infringes on your rights. If you don't get a flu shot, and you get sick - too bad. That is your decision and you get to suffer for it. I think you would agree that your decision not to get a flu shot is your choice, and getting sick as a result of it is an inconvenience you are willing to risk.
But consider, if you get sick, how many other people do you infect? How did your exercise of your rights impact others around you? If I get a shot, I have a 80-90% immunity. If I work in close proximity to you, I will test my immunity against your contageous condition. But, if we both had our shots - the odds of me getting sick from you drops dramatically (20% chance you got sick x 20% chance of me catching it from you yields only a 4% odds of getting sick). Now, if the Swine Flu were absolutely horrible, I'd say let's make it a legal requirement to get the shot, just like Polio. The fact is that the Swine Flu is nasty, but not as bad as the press would make it out to be. But the fact remains, vaccines are not an imposition of tyranny on everyone, they are there for the protection of society as a whole.