There are various programs to help people who can't afford health care, especially for children, but there are a lot of gaps in the system, too. That's assuming the people that do qualify for the program even know about it. Even for people who do have health care a co pay can be a major barrier to preventative care.
I'm sure lots of people will read that and think I'm overreacting or overstating the problem, but I'm really not. The statistics on vaccine coverage by various measures of poverty are very telling. I think it's difficult if you've had a life of some privilege (and by privilege I don't just mean rich, I mean things like white, raised by both parents, graduated high school, etc) to understand the decisions that families make in these situations, especially when poverty is so often linked to a lack of adequate information and education about things like health care.
Thats why I was asking the eligibility parameters (thx slmommy for posting the link), I really hope ObamaCare gets through the Supreme Court - people need to be able to access basic healthcare.