With two weeks to go until the end of open enrollment, the Health and Human Services Department announced that a "weekend wave" sent the total enrollment number over 5 million.
That means some 800,000 Americans have signed up for coverage in the past two weeks, given that February ended with only 4.2 million consumers signed up.
The number is still 1 million short of the Congressional Budget Office projection that the exchanges would see 6 million enrollees in their first year.
"The last several days have been the busiest since December, with the Call Center taking more than 198,000 calls on Thursday alone — the busiest day since December 23 — and more than 130,000 calls over the weekend," Centers for Medicare and Medicaid Services Administrator Marilyn Tavenner wrote in a blog post. "Last week, HealthCare.gov saw more than 4 million visits — and an additional 1 million visits this weekend."
CMS spokesman Aaron Albright said in an email that the agency has no further details at this time.
Open enrollment ends March 31.