A dramatic surge of nearly 3.8 million enrollments in March and April helped bring ObamaCare's total sign-up number to more than 8 million, the Obama administration revealed Thursday.
Another 4.8 million people signed up for Medicaid and the Children's Health Insurance Program at the state level, contributing to an informal HHS tally that almost 13 million people are covered because of the healthcare law.
The numbers from the Department of Health and Human Services (HHS) are likely to be the final word on enrollments in ObamaCare’s first sign-up period.
The administration cheered the data as a signal that the Affordable Care Act is fulfilling its goal of bringing healthcare coverage to millions of people.
Officials also predicted that plan premiums would remain stable in every state next year despite some expert and industry projections to the contrary.
While the 28-percent share of younger people falls short the 40 percent seen as ideal, that may not make a difference to premiums.
"We believe, based on the data we've seen and independent data, that premiums will be stable and that the risk pool is sufficiently large and varied to support that kind of pricing," said HHS Office of Health Reform Director Mike Hash on a conference call.
Republicans were notably quiet after the report's release, though a handful of staffers questioned the numbers on Twitter.
Thursday's report contained a wealth of fresh detail about who signed up for private plans on the exchanges.
For the first time, HHS revealed self-reported data on ethnicity.
Seventeen percent of people who signed up through the federally facilitated exchanges were African American, 11 percent were Latino and 8 percent were Asian or Pacific Islander, the report stated.
The share of Latino enrollments notably fell short of the total population eligible for coverage, though administration officials said they would work to correct this for 2015.
The department also hinted at how many people were previously uninsured, though officials cautioned the data was not reliable.
About 5.2 million enrollees were required to answer a question about their coverage status. Of this group, only 13 percent said they already had a health plan.
If accurate, this finding would point to a higher proportion of uninsured people signing up on the exchanges than private estimates have suggested.
The detailed enrollment breakdown came after almost two months of scattershot disclosures from the administration.
The White House announced when sign-ups hit 6 million, 7.1 million and 8 million, but did not consistently reveal important points like the age distribution.
The total number of sign-ups is now 8,019,763, the administration said.
Several pieces of data remained missing from Thursday's report, however, including an official number of people who have activated their coverage by paying their first premium.
Insurers say the figure is 80 to 90 percent, and experts believe it will rise when new policyholders hit their first payment deadline.
But the administration is sure to field more criticism until it releases its own data later this year.
The HHS release, while providing state-by-state numbers for the first time since March, also did not contain enrollments by health plan.
Centers for Medicare and Medicaid Services spokeswoman Julie Bataille said she knew of no current plans to release those numbers.
State by state performance varied widely.
In more than 12 states, according to HHS, enrollment doubled since March 1. These included Florida and Texas.
A total of 20 states, however, fell short of previous enrollment projections by federal health officials.
The numbers are likely to play a major role in ongoing political debates about the Affordable Care Act.
Republicans are hoping the law's unpopularity will boost their candidates and help them take the Senate in November.
A total of 85 percent of enrollees received federal subsidies to lower the cost of their plans, HHS reported.
This is roughly equal to the number anticipated by the Congressional Budget Office (CBO) in a report this month.
The CBO has estimated that the law will narrowly reduce the deficit, as the cost of its benefits are offset by new taxes and budget cuts.
Republicans argue this outcome is unlikely given the high number of people likely to receive subsidies or Medicaid coverage.
--This report was updated at 3:56 p.m.