NEW YORK ( MainStreet) — The latest data from the Department of Health and Human Services (HHS) is that the enrollment of young people, the so-called Invincibles, fell short of constituting 40% of the total enrollment that would be necessary for the financial viability of the Affordable Care Act.

"Nearly 2.2 million people have selected plans from the state and federal marketplaces by Dec. 28, 2013 (the end of third reporting period for open enrollment)," HHS said in a statement dated January 13. "The report provides the first demographic information about enrollees. December alone accounted for nearly 1.8 million enrollees in state and federal marketplaces."

The report's significant findings revealed that of the 2.2 million enrollees only "24% are between the ages of 18 and 34." This is a little more than half of what is required.

Various groups like the Kaiser Family Foundation and others have stated that the demographic cohort of adults, ages 18 to 34, need to comprise 40% of those enrolled in the ACA. If not, then the plan will have problems. Some 9% of those are between the ages of 18 and 25, while 15% are between the ages of 26 and 34.

The largest percentage belongs to the 55 to 64 age group; some one in three enrollees (33%) were in this age bracket.

But HHS is not concerned about this. Quite to the contrary, the department is optimistic. The HHS report states that there has been an effort to encourage young people to enroll in "Marketplace plans" for two reasons. One is because this cohort usually does not have health insurance, so their enrollment will satisfy the mission of the ACA. The other is "to help to ensure a favorable risk mix." Ergo, young people will be able to subsidize the older people - as is the case with any insurance plan.

The HHS expects that younger people will wait until March 31, 2014 - the end of the open enrollment period - to sign up. This will balance out the presently skewed figures.

The health insurance industry trade association the America's Health Insurance Plans (AHIP) takes a similar tack. The group is sync with the Obama administration and also believes that any concerns must wait until the final tally.

"It is important to look at who signs up over the entire six-month open enrollment period to determine what impact enrollment will have on the marketplace," AHIP Deputy Press Secretary Clare Krusing said in an email. "The focus needs to be broader than just the total number of people who enroll to also include the age and health of the population covered. There is broad agreement that if young, healthy people choose not to purchase coverage, and only those who are older and costlier choose to sign up, then costs will increase for everyone with insurance."