Story highlights Nearly half a million Americans chose plans on HealthCare.gov in the first week of 2015 open enrollment

Over 1 million Americans submitted applications for coverage

Facing new scrutiny over the law, HHS will put out weekly summaries of enrollment data

Nearly half a million Americans chose plans on HealthCare.gov during the first week of open enrollment for 2015, a sign the federal health care site has improved since its rocky rollout last year.

The Department of Health and Human Services said Wednesday that more than a million Americans submitted applications for coverage in the first week of open enrollment for 2015.

From Nov. 15-21, 462,000 Americans chose plans on HealthCare.gov, with a little under half, or about 220,000, of those being new purchasers. Those figures only include numbers from the 37 states that offer coverage through the federal site, rather than state-based exchanges

That's a marked improvement from the 2014 open enrollment period, when 27,000 people signed up for coverage on HealthCare.gov during the entire first month.

"We had a solid start, but we have a lot of work to do every day between now and February 15," HHS Secretary Sylvia Burwell said in a statement. "People are ready to get covered, and visitors to HealthCare.gov are seeing more competition, affordable options and an improved consumer experience."

HHS said that about 3.7 million Americans used HealthCare.gov during the first week, and nearly 1.6 million used the "window-shopping" tool to browse coverage options over the week.

The administration has previously predicted that between 9 and 9.9 million to enroll in health coverage under Obamacare by the time the 2015 open enrollment period ends, at the end of February.

Despite the improved enrollment figures and functionality of the site, HHS is not out of the woods with its implementation of the law.

News last week that initial enrollment figures were inflated by hundreds of thousands of dental plans brought new scrutiny to the law, prompting Burwell to apologize and pledge that "this kind of mistake" wouldn't happen again.

No mention of the inflated numbers was made in Wednesday's announcement of the latest enrollment numbers, but HHS is planning to put out weekly enrollment numbers and a more detailed outline of the enrollment figures every month, a move that might help quiet critics.