Who enrolled in health law coverage and what do they bring to the risk pool?

The final days of open enrollment were marked by a surge that helped the Obama administration clear a key milepost. But not yet known is what this population actually looks like. Were these people previously uninsured? Did young people sign up in big enough numbers? And will the insurance model actually work?   

The Wall Street Journal: 5 Questions About Obamacare's 7 Million Enrollees
What does the 7 million mark mean for the health law? It tells us the final days of enrollment attracted a surge of consumers and that the sometimes-panicked rush by the Obama administration to fix HealthCare.gov after a disastrous launch largely paid off. What the politically crucial milestone doesn't reveal, however, is much about whether the law will work. For instance, we still don't know whether the new marketplaces will make much of a dent in the number of uninsured people, or if the business will prove sustainable for insurers (Weaver, 4/1).

The Washington Post's The Fact Checker: Obamacare Enrollment Numbers: What We Know And What We Don't Know
With the enrollment period ended on March 31, it's time to do the numbers. What do we actually know about Obamacare enrollment numbers -; and what is missing? (Kessler, 4/2).

The New York Times: Newly Enrolled, But Not Counted By Insurance Exchange
Millions of newly insured people are hiding in plain sight. They are the people who have bought new health insurance since the start of this year but have chosen for one reason or another to bypass the state and federal exchanges that opened last year under the Affordable Care Act. While the exact number is unknown, some health care experts estimate that it may be in the millions (Thomas, 4/1).

CBS News: Did Enough "Young Invincibles" Sign Up For Obamacare?
The lines were long at last-minute enrollment events for California's health-care exchange. The Covered California website could not keep up and logged people out as they tried to sign up. California has now enrolled more than 1.2 million people, nearly 156,000 in just the past week (Tracy, 4/1).