The international AIDS conference in Washington has already made two points clear. There is no prospect that scientists will any time soon find the ultimate solutions to the AIDS epidemic, namely a vaccine that would prevent infection with the AIDS virus or a “cure” for people already infected with the virus. Even so, health care leaders already have many tools that have been shown in rigorous trials to prevent transmission of the virus, making it feasible to talk of controlling the epidemic within the foreseeable future. The only question is whether the nations of the world are willing to put up enough money and make the effort to do it.

An estimated 34.2 million people around the world are currently infected with H.I.V., the virus that causes AIDS. According to the United Nations agency that tracks the disease, some 23.5 million of these live in sub-Saharan Africa and another 4.2 million in India and Southeast Asia. About 1.1 million live in the United States.

This conference is the first in more than two decades to be held in the United States. It became possible only when a benighted policy that prohibited entry visas for people suffering from AIDS or infected with H.I.V. was finally overturned in 2009. It was “a bad policy, based on faulty science, that ran contrary to America’s deepest values,” Kathleen Sebelius, the secretary of health and human services, told the conference.

There has been optimistic talk at the conference about accelerating the search for a “cure” that would allow people to eventually stop taking the drugs that have prolonged many lives for decades — and about developing a truly effective vaccine. But Dr. Anthony Fauci, the American government’s top AIDS expert, made clear just how difficult those tasks will be. He told the conference that a cure was “way upstream” and depends on future research breakthroughs, and he called the most successful vaccine trial to date “humbling” because it showed only a modest degree of efficacy.