With 37 million people currently living with human immunodeficiency virus (HIV) worldwide, the question of whether a cure will be found for the pandemic took centre stage in Durban, South Africa, on Saturday, ahead of today’s start of the 21st International AIDS Conference (AIDS 2016).

However, not even the leading experts in HIV cure research can confidently say when, or if, a cure will ever be found for the dreaded killer disease. Speaking at the International AIDS Society (IAS) Global Scientific Strategy: Towards an HIV Cure 2016 press conference, Anthony Fauci of the United States National Institutes of Health (NIH) held nothing back about the prospects for developing a cure or sustained remission for HIV.

“I don’t think that anybody on this table can tell you with any definitive confidence that we will (find a cure), but I think what we are seeing on stage is the commitment in trying to address the challenge,” he said.

Fauci was part of a six-member panel which also included Nobel Laureate Françoise Barré-Sinoussi of France, co-discoverer of HIV with Luc Montagner in 1983, and co-chair of the IAS Towards an HIV Cure Initiative; Jintanat Ananworanich of the United States Military HIV Research Programme; Steven Deeks of the University of California in San Francisco, US; Sharon Lewin of the Doherty Institute, University of Melbourne in Australia; and Giulio Maria Corbelli of the European AIDS Treatment Group.

“So we all said, one way or the other, that this is not going to be easy; this is not like any other infection that we have ever seen,” Fauci explained.

Fauci, who is the director of the National Institute of Allergy and Infectious Diseases, said the fundamental principle underscoring the difficulty with HIV was that it was unlike virtually every virus that attacked the body. He explained that, at the end of the day, the body always showed that it could clear the virus and leave the affected individual with more or less sustained immunity against it.

“We don’t have that experience with HIV,” Fauci admitted. “We have to do things that nature has never before done. So that’s not impossible, but that’s not going to be easy and for that reason, I can’t tell you when we are going to have a cure, because I am not sure if we are going to have a cure,” he said.

Some 18,000 scientists, policymakers, advocates, and people living with HIV will converge in Durban for AIDS 2016 from July 18 to 22, which will highlight the latest accomplishments and challenges in an area of scientific inquiry that few could have imagined at the first Durban conference 16 years ago — the prospect of developing safe, effective, and global, scalable approaches to curing or achieving sustained remission of HIV infection.

Barré-Sinoussi told journalists from across the world that HIV cure research was in its “formative stage” but it had the potential to alter the future of the HIV epidemic.

On a brighter note, Fauci suggested that the science on HIV/AIDS had come a long way, especially in relation to treatment with antiretroviral therapy (ART), which had radically changed the face of HIV infection from a lethal disease to a manageable chronic disease.

However, ART is not curative and given the challenges associated with providing lifelong therapy to 37 million people living with HIV, there was increased interest in developing a cure.

Interestingly, according to the UNAIDS Global AIDS Update from June 2016, only 17 million of these individuals are currently accessing ART.

“When I think of a cure, I don’t use ‘cure’ as an umbrella term, I use sustained viological persistence and there are two ways to approach that — one is the elimination of the virus and two is to control the virus without its complete elimination by a variety of means,” Fauci said.

He explained that labs throughout the world are exploring a variety of ways to cure HIV, from attempting to flush the virus out of the body and modifying the host through stem cell transplant to gene editing.

“…As difficult as the scientific problem is, I am confident that we are going to make progress that is going to be impressive,” he insisted.

Another panelist, Lewin, was also upbeat about the advances made in the search for a curative strategy in the last four years.

“We can all see how hard this effort has been, but there have been some advances,” she shared. “The first thing is around terminology. We speak about a ‘cure’, I think that is an aspirational goal. To eliminate HIV permanently from someone, we know that is going to be really, really difficult.”

She said the focus in the interim was to achieve remission — allowing people to safely stop antiretroviral therapy with the virus being under control.

Lewin reported on a number of cases in which this had been possible, notably viral rebound being substantially delayed in the setting of stem cell transplantation or of very early ART in an infant/and long-term post-treatment off ART being achieved.

“We now have monkey models of SIVs or the Simian version of HIV, that can be very well controlled on treatment…” she continued.

As the search for an HIV cure intensifies, the IAS has expanded the scope of its scientific strategy first published in 2012, broadening it beyond biomedical research to include the social and behavioural science. The ‘Global Scientific Strategy: Towards an HIV Cure 2016’ describes the crucial knowledge gaps and research questions in the field.

The International AIDS Conference, which was first convened during the peak of the AIDS epidemic in 1985, is reportedly the largest conference on any global health or development issue in the world. Each conference is an opportunity to strengthen policies and programmes that ensure an evidence-based response to the epidemic.