IN THE HISTORY of global public health, there has been nothing quite like it. Since 2003, Congress has appropriated more than $38 billion for the President’s Emergency Plan for AIDS Relief, known as PEPFAR — the largest global health initiative ever undertaken focused on a single disease. Congress reauthorized the program for five years in 2008 and asked for a report card. Now, after four years of work, some 400 interviews and visits to 13 nations, the Institute of Medicine of the National Academy of Sciences has provided a 678-page examination of this incredibly ambitious program.

The verdict: PEPFAR has been “globally transformative,” a “lifeline” and credited around the world for “restoring hope” in the long, difficult struggle against HIV/AIDS, which has taken nearly 30 million lives over three decades. Furthermore, the program “has saved and improved the lives of millions.” It set big goals “and has met or surpassed many of them.” One small statistic speaks volumes: As of September, the U.S. government has supported antiretroviral treatment for more than 5 million men, women and children. This is a vast increase from a decade earlier.

When the program began, there were plenty of doubts about whether HIV prevention, treatment and care could be scaled up in low- and moderate-income countries and make a difference. In the 10 years since, PEPFAR has demonstrated that it could be done. In the next decade, the challenge will be to sustain it, and much work remains. The epidemic is still being driven by new HIV infections — about 2.5 million worldwide in 2011, or 7,000 new infections per day.

Treatment and care help those already afflicted, but prevention is the key to slowing the rate of new infections. Fortunately, research has produced both hope for new prevention techniques, such as a major clinical trial that proved antiretroviral drugs can help protect the sexual partners of an infected person, and success in reducing infection rates through circumcision.

In the early years, PEPFAR’s prevention programs were considered too narrow. Now, the report notes, there has been a needed “evolution” toward broader efforts. The report calls for striking a balance between biomedical techniques that are known to be relatively effective, such as providing condoms and antiretroviral treatments, and efforts to change behavior, the effectiveness of which are less well documented.

Another PEPFAR shift, already underway, is to move away from providing services directly — the kind of rapid action that brought such success in the early years — to helping countries fight HIV/AIDS on their own, in their existing health-care systems.

Hard work is still ahead, and there may be fewer glowing report cards like this one. But Congress and the administration should take note: PEPFAR has changed millions of lives for the better and can do so in the next decade as well.