LONDON -- For the first time in the global AIDS epidemic that has spanned four decades and killed 35 million people, more than half of all those infected with HIV are on drugs to treat the virus, the United Nations said in a report released Thursday.

AIDS deaths are also now close to half of what they were in 2005, according to the U.N. AIDS agency, although those figures are based on estimates and not actual counts from countries.

Experts applauded the progress, but questioned if the billions spent in the past two decades should have brought more impressive results. The U.N. report was released in Paris where an AIDS meeting begins this weekend.

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"When you think about the money that's been spent on AIDS, it could have been better," said Sophie Harman, a senior lecturer in global health politics at Queen Mary University in London.

She said more resources might have gone to strengthening health systems in poor countries.

"The real test will come in five to 10 years once the funding goes down," Harman said, warning that some countries might not be able to sustain the U.N.-funded AIDS programs on their own.

The Trump administration has proposed a 31 percent cut in contributions to the U.N. starting in October.

According to the report, about 19.5 million people with HIV were taking AIDS drugs in 2016, compared to 17.1 million the previous year.

UNAIDS also said there were about 36.7 million people with HIV in 2016, up slightly from 36.1 million the year before.

In the report's introduction, Michel Sidibe, UNAIDS' executive director, said more and more countries are starting treatment as early as possible, in line with scientific findings that the approach keeps people healthy and helps prevent new infections. Studies show that people whose virus is under control are far less likely to pass it on to an uninfected sex partner.

"Our quest to end AIDS has only just begun," he wrote.

The report notes that about three-quarters of pregnant women with HIV, the virus that causes AIDS, now have access to medicines to prevent them from passing it to their babies. It also said five hard-hit African countries now provide lifelong AIDS drugs to 95 percent of pregnant and breast-feeding women with the virus.

"For more than 35 years, the world has grappled with an AIDS epidemic that has claimed an estimated 35 million lives," the report said. "Today, the United Nations General Assembly has a shared vision to consign AIDS to the history books."

The death toll from AIDS has dropped dramatically in recent years as the wide availability of affordable, life-saving drugs has made the illness a manageable disease. But Harman said that "Ending AIDS" - the report's title - was unrealistic.

"I can see why they do it, because it's bold and no one would ever disagree with the idea of ending AIDS, but I think we should be pragmatic," she said. "I don't think we will ever eliminate AIDS, so it's possible this will give people the wrong idea."