Some 2.5 million people are still becoming infected with HIV every year even as drugs have slashed the death rate and virus-carriers live longer than ever, a global AIDS study said Tuesday.

New infections have plateaued for the past 10 years after a steep dip from the peak rate of 3.3 million in 1997, said the authors of a comprehensive analysis in The Lancet HIV journal, and described the trend as "worrying".