The report, prepared by the joint United Nations Programme on HIV/Aids (UNAids), said this showed that an "unprecedented acceleration in the Aids response is producing results". But while those involved in the local Aids response have hailed the results, they say now is not the time for complacency.
Dr Mbulawa Mugabe, UNAids deputy regional director for eastern and southern Africa, said the report showed that what used to take a decade to achieve is now taking two years.
"The pace has quickened, which means the investments that have been committed to the Aids response are actually paying dividends," he said.
However, Mugabe warned that in order to get the best value for money from the Aids response, "smart investment thinking" was needed.
"We need to do more with what we have, look at whether we can introduce efficiencies in the manner in which we run programmes, and make sure that TB and HIV programmes share resources," he said.
"We need to look at putting money on those interventions where there's clear evidence it's making a difference."
Treatment programmes, which help lower patients' viral loads and so make them less infectious, programmes to prevent the transmission of HIV from mother to child, and male circumcision, have all shown clear benefits for reducing infection rates, and should be pursued with vigour.
The report has shown encouraging improvements in sub-Saharan Africa, which has seen a 25% decline in new HIV infections over the past 10 years.
Between 2005 and 2011, the number of people who died from Aids-related illnesses in the region declined by 32% to 1.2-million. At the same time, the number of people living with HIV who died of tuberculosis (TB) also fell by 28%.
One of the biggest successes for the region has been in preventing the transmission of HIV to children. In just two years, the number of children who were newly infected with HIV dropped 24%.
"Wider access to treatment is saving lives," said the report. "Since 1995, antiretroviral therapy (ART) has added approximately nine million life-years in sub-Saharan Africa."
This week it emerged that Cotlands,South Africa's first children's Aids hospice has opted to close its Gauteng hospice unit after recording zero Aids-related deaths for three years running. The organisation put the success down to a decline in HIV infections among babies as a result of PMTCT programs. Access to ART has also meant that children already infected with HIV are able to live longer and healthier lives, further reducing the need for hospice. Cotlands chief executive officer Jackie Schoeman said that the closure of its Aids hospice in Gauteng will allow the organisation to broaden its services to a wider range of children.
Professor Francois Venter, HIV clinician and deputy director of the Wits Reproductive Health and HIV Institute, said the majority of the effect seen in the report is clearly due to better coverage with antiretrovirals.
"They have contributed to the huge reduction in Aids and TB deaths, and to the massive drop in transmission to children. There is very good evidence that they are also contributing to the drop in new adult infections [because] when you go on successful treatment, you stop being infectious. I think it is no coincidence that this downturn in South Africa occurred as expansion of the ART programme happened," he said.
Better access to ART has also been credited with the improved life expectancy in South Africa. Last month the South African Medical Research Council (MRC) reported that the mortality rate for children under the age of five had dropped dramatically from 73 for 1 000 live births to 42 per 1 000 live births. In addition, the average life expectancy in the country jumped from 54 in 2005 to 60 last year. The MRC credited the rollout of ART for the improvements.
But Venter said he worried that the trend would reverse if clinics continue to experience ART drug stockouts – while the national health department is doing a good job at getting cheaper drugs, because of provincial inefficiencies, these don't always arrive at clinics. "A site without ART should be a national emergency," he said.
Dr Fareed Abdullah, chief executive officer of the South African National Aids Council, also advised cautious optimism when considering the results. While the number of Aids-related deaths in South Africa had dropped dramatically – by about 100 000 – in the last few years, he said, there are still a quarter of a million Aids-related deaths in the country each year.
"South Africa has 1.7-million people on treatment. But even that we cant be complacent about because we need to ensure the 1.7-million people take their pills every day, that they get good healthcare and that the health system works effectively for them because if they're not taking the treatment properly, we are in danger of increasing resistance and treatment failure," he said.
Abdullah said adherence programmes – with buy-in from doctors, nurses, pharmacists and community healthcare workers, in conjunction with communications technology like SMS reminders – could help patients stick to their treatment regimes.
Meanwhile Mitchell Warren, executive director of Avac, a global advocacy group for HIV prevention, has called for a change in the way we assess the success of the Aids response.
Instead of tracking the progress of the epidemic over a decade, Warren suggested that governments select a handful of clear, easily-attained targets – like the number of people being tested and linked to care if they need it – and to track these on a quarterly basis.
This would allow authorities to "course correct" should they find that basic interventions are not being implemented.
"It's a different kind of accountability and management system [but] its doable. Businesses do it all the time," he said.
Warren said that while political commitment and financial investment was increasing, there was still a large gap in resources that needed to be filled.
According to UNAids, the global gap in resources needed annually by 2015 is now at 30%. Last year $16.8-billion was available for the Aids response and the need for 2015 is estimated at between $22-billion and $24-billion – a gap of about $7-billion.
"We need to push hard to get that $7-billion but we also need to work harder to invest that money appropriately," said Warren. "We need to ensure that every dollar, rand, euro, or shilling is spent more wisely."
Warren said that while linking testing to treatment was key to preventing new infections, investment in research towards an Aids vaccine was essential.
"We're talking about many more years of this struggle and a vaccine has to be central to that struggle. We've never ended an epidemic without one. While the tools [for prevention] are good, and getting better, a vaccine is essential to offering people a better option," he said.