reasons for incomplete coverage of children:
1. S-CHIP was not required to cover “all children” in all “poor households”: S-CHIP eligibility set at 200% FPL, but beyond that, varies with state, therefore:
-”bureaucratic implementation” varies by state: enrollment requirementes, education efforts, and the states, facing budget problems combined w/ decreasing federal payments, have had to cut back on S-CHIP enrollment and returned money to the feds
…creating many barriers to take-up. So, a combination of parents deciding not to sign up as well as not knowing about the program at all.
2.Estimated illegal immigrants change eligibility estimates 3-5% at most, but certainly, this is hard to measure
*for more info on changes in S-CHIP coverage from 1996-2001, see Cunningham, et al in Health Affairs, 2003. http://content.healthaffairs.org/cgi/content/full/22/4/163#R25
*for info on the financial troubles of S-CHIP, many articles abound as early as 2001: http://www.cbpp.org/11-8-01health-sum.htm

As for adults:
Qualifying for Medicaid as an adult following inpatient admission hardly counts as “access to health insurance.” More like, access to some catastrophic coverage. The uninsured who qualify at this point have not had access to coverage for primary care or ambulatory care in general. As you pointed out, many will still not qualify for Medicaid- not just single males, but many adults w/o dependent children who do not have a disabling or terminal condition.

Note that often these estimates of the uninsured are those who are uninsured for 12 months or more- this does not include a substantial population cycling through uninsurance, private and public insurance. Those on the margins can have nearly comparable limited access to care and poorer health status.