>> every vaccine carries a risk of complication and side effect <<
Of course. Any well-informed person knows that.
But the statistics are something like the following:
One out of about every 500,000 children who receive the measles vaccine will suffer death or brain damage as a result.
But on the other hand, one out of about every 1000 children who get measles will suffer death or brain damage.
Do you want your child to be one in 500,000? Or one in 1000?
The measles vaccine is actually the MMR vaccine. Have the risk factors for the mumps and rubella vaccines been added in? And if there are multiple doses of MMR required, does the risk increase?
Now let's assume your numbers are accurate. If you get the shot, you are inducting yourself into the 1 in 500,000 pool. If you don't get the shot, you still may not get measles, in which case your odds are not actually 1 in 1000 but zero.
Also, these statistics are only good for general assessments. If you know or suspect your child has risk factors one way or the other, that will have to factor into the decision.
And this is why I insist that parents have to make the decisions and not the state. You can quote statistics left and right, but if you're a parent who's been talked into something against your better judgment and your kid suffers because of it, what could possibly give you solace? "We took one for the team?"