CHICAGO (Reuters) - The first national analysis of the impact of the Affordable Care Act on people with HIV showed significant increases in health insurance coverage among people infected with the virus that causes AIDS, according to a report released on Tuesday.

FILE PHOTO - The federal government forms for applying for health coverage are seen at a rally held by supporters of the Affordable Care Act, widely referred to as "Obamacare", outside the Jackson-Hinds Comprehensive Health Center in Jackson, Mississippi, U.S. on October 4, 2013. REUTERS/Jonathan Bachman/File Photo

The report comes as Republican lawmakers and President Donald Trump discuss ways to repeal the health insurance law, also known as Obamacare, which expanded insurance coverage to 20 million people.

The study was based on data from the U.S. Centers for Disease Control and Prevention’s Medical Monitoring Project, which gathers nationally representative information about people who have or are being treated for HIV infections - but not all people with HIV. It excluded the undiagnosed or those diagnosed but not being treated.

According to the report, much of the increase in coverage came from the 31 states and the District of Columbia that expanded access to the federal Medicaid program for the poor and disabled.

Nationwide, Medicaid coverage of people being treated for HIV rose to 42 percent in 2014, up from 36 percent in 2012, the year before the law went into effect, according to the report by the Kaiser Family Foundation.

In the Medicaid expansion states sampled, Medicaid coverage rose to 51 percent in 2014, up from 39 percent in 2012, and the share of uninsured fell to 7 percent from 13 percent.

“It basically demonstrates that the Medicaid expansion made a significant difference in the lives of people with HIV in providing new and expanded coverage,” Kaiser health policy analyst Jennifer Kates, one of the report’s authors, said in a telephone interview.

The findings underscore some of the difficulties lawmakers face as they go about repealing and replacing Obamacare.

Under the Affordable Care Act (ACA), states received funding to expand Medicaid eligibility to nearly all individuals with incomes at or below 138 percent of the official poverty level. The law also did away with other eligibility requirements, such as disability or being pregnant, that prevented many poor adults with HIV from gaining Medicaid coverage.

The ACA also banned the insurance industry practice of denying private insurance coverage to people with pre-existing conditions. And it included provisions that prevented insurance companies from setting significantly higher rates for people with HIV, or imposing annual or lifetime coverage limits.

These changes may have helped some people with HIV gain access to private insurance, but the biggest impact came from Medicaid expansion.

“The main takeaway is that for a population that faced a pretty significant barrier to Medicaid before the ACA, expansion of Medicaid made a big difference,” she said.

If efforts to repeal the ACA result in the elimination of Medicaid expansion, the study said, “most people with HIV who gained coverage would likely lose it unless states adopt alternative approaches to retaining the newly covered population in the program.”

Disruptions in care pose significant challenges to people with HIV because they can increase the chance that the virus will become drug resistant.

Studies have shown that taking drugs to suppress the virus dramatically reduces the risk of spreading HIV to others.

New figures released by the CDC earlier on Tuesday show the number of annual HIV infections in the United States fell 18 percent between 2008 and 2014, from an estimated 45,700 to 37,600.

CDC researchers said they believe the declines in annual HIV infections are due, in large part, to efforts to increase the number of people living with HIV who know their HIV status and are virally suppressed — meaning their HIV infection is under control through effective treatment.

“This is a top public health priority,” CDC said in a statement.