Check Airman
Here's the thing: vaccines are not 100% safe. The argument that the benefits out-weight the cost is not ethical, as in reality it is saying: it is acceptable to either kill or severely cripple few for the benefit of the many.
In essence it comes down to this: vaccines are a giant russian roulette. We don't know exactly what the odds are, but even if we say they are 1 in a million, we are knowingly killing people in order to save other people.
Would you pull the trigger of that gun against your kid, even if it would mean they were supposedly safe against something else in return? Would you really? I think most people would not. Something abut the gun makes the danger perceivable, where as "1 in a million" against injection sounds more assuring, but it is not.