A total of 46.3 million people in the United States do not have health coverage, a trend that has been rising in the past 15 years, said a US survey published Tuesday.
There was good news for children in the data from the 2011 National Health Interview Survey, which showed that seven percent of US youths were uninsured last year at the time of the interview, compared to 13.9 percent in 1997.
Young adults also appeared to benefit from increasing coverage, with 3.1 million people age 19-25 gaining health coverage from September 2010 to December 2011, an increase from 64.4 percent to 74.8 percent.
The Department of Health and Human Services hailed the rise in coverage for young adults as a direct result of President Barack Obama's signature health care reform package that since 2010 has allowed youths to stay on their parents' plan until their 26th birthday.
"That is terrific news because in the past many young adults just starting their careers or still studying struggled to find affordable coverage," said HHS Secretary Kathleen Sebelius.
"Today, three million more young Americans are no longer living with the fear and uncertainty that comes when you don't have access to health care."
But the overall picture for adults aged 18-64 showed lack of coverage remained high, even though down slightly from its 2010 peak.
For that group, lack of health insurance coverage was 21.3 percent in 2011, making up 40.7 million people, according to the data from the Centers for Disease Control and Prevention.
The study recorded the fewest uninsured adults in 1997 (13.9 percent). The high point came in 2010 when 22.3 percent of the population was uninsured.
"There has been a generally increasing trend in the percentage of adults aged 18-64 who lacked coverage at the time of interview," said the study, which was based on survey results from 32 of the 50 states.
The change in children's coverage status was largely explained by a 36.5 percentage point rise in government-sponsored public coverage for the poor from 1997 to 2011.
Meanwhile, the rate of private coverage among low-income children was 25.1 percentage points lower in 2011 than in 1997.
Private coverage held by adults also declined over the period studied.
The survey comes as the US Supreme Court is expected to rule by the end of June on lawsuits challenging Obama's health care reform package.
The ruling could halt key parts or all of the package, which aimed at requiring all citizens to have health care coverage and at creating cheaper coverage options.