President Barack Obama appealed to uninsured Americans to sign up for medical coverage before a March 31 deadline while his administration said 4.2 million people had enrolled in health plans through February.

Youth enrollment continued to expand, with 1.1 million people ages 18 to 34 signed up by March 1, an increase of 268,475 in a month, U.S. health officials said in a report. Obama made a special effort to reach young adults yesterday, exchanging barbs with comedian Zach Galifianakis while pitching the health-care law on the actor’s parody web talk-show “Between Two Ferns.”

A survey this week found the number of uninsured dropped since Jan. 1 when plans sold on the new health exchanges took effect. About 15.9 percent of Americans lack coverage this year, down from an all-time high of 18 percent in 2013, Gallup Inc. said March 10.

“That wasn’t a coincidence or something that just happened on its own,” U.S. Health Secretary Kathleen Sebelius said yesterday in a conference call with reporters. “What we’re finding is that as more Americans find out just how affordable marketplace insurance can be, more are signing up to be covered.”

The Congressional Budget Office estimates that about 6 million people will sign up this year for private plans under the new insurance marketplaces created by the Patient Protection and Affordable Care Act known as Obamacare. Another 8 million are expected to join Medicaid, the government program for the poor that is being expanded in at least 25 states. The goal of the 2010 law is to reduce the country’s estimated 48 million uninsured.

More Anticipated

“Millions more Americans” are expected to sign up for private plans before the March 31 enrollment deadline, said Julie Bataille, a spokeswoman for the Centers for Medicare and Medicaid Services. Her agency has beefed up computer systems supporting the federal enrollment site, healthcare.gov, in anticipation of higher traffic, she said.

Administration officials said they have no information on how many people were uninsured before they signed up under the Affordable Care Act, instead pointing to the Gallup survey and other studies by independent groups. About 27 percent of people enrolling in February were previously uninsured, according to a March 6 survey by the consulting firm McKinsey & Co.

“Until the administration provides details about who was previously uninsured and who has paid, these reports tell us nothing about the success or failure of the president’s health- care law,” Noelle Clemente, a spokeswoman for Republicans on the House Energy and Commerce Committee, said in an e-mail. “The president’s recent media appearances suggest that the administration is panicked as the March 31 deadline fast approaches.”

Life Changes

After March 31, open enrollment in private health plans is closed for 2014 and people can only sign up if they experience life changes such as getting married or losing a job. Americans who don’t carry insurance starting April 1 will be liable for tax penalties of as much as 1 percent of their income.

The administration isn’t allowed under the health law to extend the deadline, Michael Hash, the director of the Office of Health Reform at HHS, told reporters. The CBO says it expects the government to collect $2 billion in penalties next year.

The new data on enrollment show that about 943,000 people signed up for private plans in February compared with 1.1 million in January. Administration officials expect a surge of enrollment this month as the deadline approaches, similar to the burst in December, when 1.8 million signed up before an end- of-the-month deadline for coverage starting Jan. 1.

State Leaders

California continues to lead the nation in enrollment, with 869,000 people in private plans. Florida is second with 442,000 -- the most of any state that relies on the federal enrollment system, healthcare.gov.

The administration said 83 percent of those who selected a plan are eligible to receive financial assistance to help pay premiums or other plan costs.

About 25 percent of people who have enrolled are from ages 18 to 34, a key demographic because young adults are generally healthier than older people. Insurers need as many young people on their rolls as possible to balance the cost of caring for older, sicker people and avoid future premium increases.

Before the faltering start of healthcare.gov in October, the administration said it wanted about 40 percent of people enrolling to be younger than 35.

Promotional Push

To that end, the administration is plowing resources into contacting young adults. Valerie Jarrett, a senior adviser to Obama, gave interviews yesterday on three radio programs aimed at young people and the White House hosted an event with entrepreneurs, researchers and graduate students that it called “#GeeksGetCovered.” Obama’s appearance on “Between Two Ferns” drew 6.1 million viewers as of 5 p.m. New York time yesterday at the site that produced it, funnyordie.com.

The show began with trademark rude questions from Galifianakis -- “I have to know, what is it like to be the last black president?” Eventually the two segued to the Affordable Care Act.

“Have you heard of healthcare.gov?” Obama asked the actor best known for his roles in the three “Hangover” movies.

“Here we go,” Galifianakis said, sighing. “OK, let’s get this out of the way. What did you come here to plug?”

A stunt at the end of the show revealed that it was taped at the White House. About 19,000 people visited healthcare.gov after viewing the president’s appearance with Galifianakis, Bataille said.