The cure to AIDS is an aspirational goal. (Representational Image)
Researchers praised progress made towards developing an HIV cure, but said it was impossible to tell when or even if a cure for the devastating epidemic would be found.
Some 18,000 delegates from around the world have converged on the coastal city of Durban for the 21st International AIDS Conference where the latest advances in research are being presented.
Last week, scientists unveiled an aggressive strategy to develop an outright cure, but many of those in Durban warned it was still a young field of research.
"A true cure is an aspirational goal," said principal author of the strategy Professor Sharon Lewin.
She said remission- the ability of a patient to stop taking anti-retroviral treatment and remain healthy- was the intermediate goal.
"We don't know when we will have a cure and if we will have a cure," said Nobel Medicine laureate Francoise Barre-Sinoussi, who in 1983 helped identify the human immunodeficiency virus (HIV) that causes AIDS.
"We really believe that we will be able to have sustainable remission," she said.
"That's not to say a cure is impossible, it's just to say to have a real cure is very, very hard."
In 2004, AIDS deaths peaked at more than two million.
Last year, the toll was around 1.2 million lives- a decline attributed in large part to the success of anti-retroviral drugs, which reduce the symptoms of people carrying the virus.
Scientists increasingly understand how HIV remains barricaded in tissues- such as the lymph nodes and the gut- after being beaten back by anti-retroviral therapy, the standard drug cocktail given to HIV patients.
"We still need a lot more basic research about where and why virus persists and how to harness immune response to eliminate it," said Lewin.
Research has also found starting therapy early limits the ability of the virus to establish a stronghold.
But less than half of an estimated 37 million people worldwide living with HIV receive therapy.
Over $200 million was invested in cure research last year, up from just $88 million invested in 2012.
"That trend needs to continue," said Barre-Sinoussi.