The CDC uses Australia as an annual template for our upcoming flu season and mixes US cocktails based on what they see there in the previous 6 months. On years the CDC guesses right, there is a 2.7% risk reduction score in the average US citizen chances in getting the flu. In years they guess wrong, its only a 1.3% reduction. Not getting the shot is baseline at 0%. At the individual level, the actual benefit is not all that great. On the population level, that does end up being a few million people who won't get the flu...even if they guess wrong (statistically speaking).

I don't get a flu shot because I'm scared of needles or don't see the cost / benefit. I don't get the flu shot because I am extremely lazy and that sounds like something that might require planning and effort. No dice.