Epidemiologists from Harvard University were tracking HIV-negative South Africans in the province of KwaZulu-Natal (orange).

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Originally published on February 22, 2013 8:51 am

Over the past few decades, one of the most perplexing questions in global health is how to stop HIV.

There have been campaigns involving condoms, abstinence and even the circumcision of all men younger than 46. But one relatively new strategy, called treatment as prevention, is causing quite a buzz.

The idea is to give all HIV-positive people antiretroviral drugs to drive down the levels of virus in their systems so they no longer pose a threat of transmitting the disease.

Sounds good in theory, but how well does it play out in the slums of Nairobi or the townships of Johannesburg?

Two studies published in the journal Science find that, in places where HIV drugs are widely available, the risk for new HIV infections drops dramatically and overall life expectancy increases by more than a decade.

In other words, treatment as prevention isn't just a buzz word floating around health conferences but a promising strategy for stopping HIV — even in a part of the world with one of the most severe AIDS epidemics.

Epidemiologists from Harvard University followed 17,000 HIV-negative South Africans for seven years in the province of KwaZulu-Natal. They found that, when more than 30 percent of HIV-positive people are on powerful anti-HIV drugs, it cuts the risk of contracting the virus by about 38 percent, compared to when less than 10 percent of those infected have treatment.

"The intention of this program [the South African government's antiretroviral drug program] is not treatment as prevention," Till Barnighausen, a health economist who contributed to the study, tells Shots. "The intention of this program is treatment for treatment, to save lives."

A true treatment-as-prevention model, Barnighausen says, would offer antiretroviral therapy to everyone who is HIV positive. But the South African government is providing medications only to the sickest of the sick.

Nevertheless, Barnighausen and his colleagues saw a sharp reduction in new HIV infections when drugs were widely available to the community.

"It is a program with all the failures and challenges of a real-life, public-sector, nurse-led program in southern Africa," Barnighausen says. "And despite these challenges, we see a strong effect of HIV treatment on HIV incidence. And that's extremely encouraging."

Infectious disease specialist Dr. Myron Cohen at the University of North Carolina, who wasn't involved in this study, calls the findings "a home run."

Cohen published a landmark report in 2011 showing that HIV treatment nearly eliminates the chance that an infected person will transmit the virus to a partner.

The current study, Cohen says, demonstrates that treatment as prevention doesn't just work at the individual level but also at the community level. And thus, the findings are hugely important for public health.

"It's teaching us something," he says. "You don't have to treat everybody to see a community benefit."

In a companion article, Barnighausen and his team found that overall life expectancy in KwaZulu-Natal rose more than 11 years since the province scaled up HIV treatment in 2004.

But even when studies like these show the broad benefits of anti-HIV medications, major challenges remain in getting drugs to the millions of Africans who need them, including the issue of who pays for these costly drugs.

Questions also remain about how sustainable these programs will be, especially given that HIV-positive patients are going to need to be on those drugs for the rest of their lives.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

LINDA WERTHEIMER, HOST:

This is MORNING EDITION from NPR News. I'm Linda Wertheimer.

STEVE INSKEEP, HOST:

And I'm Steve Inskeep. Good morning. The spread of powerful anti-AIDS drugs has had dramatic effects in South Africa, and not only for people with HIV. Two new studies in the Journal of Science show that where antiretroviral therapy is widely available, the risk for new HIV infections drops dramatically. Not only that - overall life expectancy increases by more than a decade. NPR's Jason Beaubien reports.

JASON BEAUBIEN, BYLINE: The province of KwaZulu Natal is one of the poorest in South Africa. It also has some of the highest rates of HIV anywhere in the world. In some of the villages tucked in to the rounded hills of this province, more than 30 percent of adults are HIV positive. Nine years ago South Africa started offering anti-AIDS drugs in government clinics in KwaZulu Natal.

Now nurse Futi Mlambo runs an HIV drug treatment program at a small clinic in the town of Eshowe. How many people do you have here on treatment?

FUTI MLAMBO: At the moment I think we've got 1,560. But we still have those who are positive but they're not yet on ARV's. Which is plus or minus 2000.

BEAUBIEN: And this is part of why the results of these new studies are so striking. As Mlambo says, the majority of the people infected with HIV still aren't on drug treatment. In fact, South Africa is only offering universal anti-AIDS drug therapy to the sickest of the sick.

South Africa's been widely criticized for dragging its feet in starting these programs. Yet despite this, Jacob Bor and his colleagues at the Africa Centre for Health and Population Studies in South Africa, found that this modest, nurse-run program increased overall life expectancy rates by 11 years.

JACOB BOR: And these are really gains that are at a scale really unprecedented in modern history outside of, you know, world wars and famines. And this is a dramatic public health achievement.

BEAUBIEN: An estimated six Million people in South Africa are HIV positive. The government, with some help from international donors, is spending hundreds of millions of dollars a year to provide anti-AIDS drugs to roughly a third of them. One big question about this program is whether it's worth the money. Bor says his study shows that anti-retroviral therapy is an extremely cost-effective public health intervention.

BOR: It costs about $1,600 for a year of life in this community, and that's - that's cheap.

BEAUBIEN: A second report also being published in Science found that providing drug therapy in KwaZulu Natal offers a level of protection against HIV to the rest of the population. This study followed almost 17,000 HIV negative adults for seven years.

The researchers found that in parts of the province that had the highest level of access to HIV drug treatment - zones where 30 percent or more of those in need of treatment were getting it - the chances of catching the virus dropped nearly 40 percent.

MYRON COHEN: I think these are terrifically important studies.

BEAUBIEN: Professor Myron Cohen at the University of North Carolina wasn't involved in these studies, but he published a landmark report in 2011 on couples where one person is HIV positive and the other negative.

Cohen showed that by getting the person with HIV on to treatment, you nearly eliminated the chance that that person's partner would contract the virus. Cohen says these new studies show a similar pattern with HIV drug treatment providing protection for the broader community.

COHEN: So I think this is a homerun, by any nature, and it's teaching us something. You know, you don't have to treat everybody in order to see a community benefit.

BEAUBIEN: But even when studies like these show the broad benefits of anti-AIDS medications, major challenges remain in getting drugs to the millions of Africans who need them. And questions remain about how sustainable these programs will be, given that HIV positive patients are going to need to be on those drugs for the rest of their lives. Jason Beaubien, NPR News, Washington. Transcript provided by NPR, Copyright NPR.