MELISSA BLOCK, HOST:
We have more details now on just who is signing up for insurance through the government's new healthcare marketplace. About a quarter of the people signing up are under the age of 35. As NPR's Scott Horsley reports, the Obama administration released its first demographic breakdown of the insurance customers today.
SCOTT HORSLEY, BYLINE: More than 2.1 million people signed up for health insurance during the first three months the website was operating. Health Secretary Kathleen Sebelius says the vast majority of those enrollments came in December, after the site's now infamous technical problems were largely resolved.
KATHLEEN SEBELIUS: Among young adults the momentum was particularly strong. There was more than an eight-fold increase in December enrollment.
HORSLEY: This is the first time the administration as offered a snapshot of who is signing up for coverage. Twenty-four percent of the enrollees are aged 18 to 34. Health policy expert Larry Levitt of the Kaiser Family Foundation says insurance companies are keeping a close eye on that figure because they're counting on the premiums paid by younger healthy people to help cover the cost of treating the old and the sick.
LARRY LEVITT: You ideally want a large number of young people in the system, but really what you want is healthy people. An insurer would much rather have a healthy 60-year-old than a sick 25-year-old.
HORSLEY: The number of young adults signing up for coverage so far roughly matches their share of the population, but it's well below their share of the target market of people who need health insurance. If that continues, insurance companies may have to adjust their rates, though Levitt says the increase would likely be small. He adds the experience in Massachusetts suggests the ages of people signing up will change over time.
LEVITT: Younger people tended to wait until the last minute to enroll and there are still two and a half months left in the open enrollment period. So I would expect enrollment to surge and that younger people will likely enroll in larger numbers.
HORSLEY: Now that the insurance website is working more smoothly, the administration says it's ramping up its outreach, encouraging more people of all ages to sign up for health insurance before this year's deadline of March 31st.
Scott Horsley, NPR News, Washington.