JOHANNESBURG — The first time the world went to South Africa for a conference on AIDS, the country's leader shocked attendees by questioning whether HIV really caused the disease.

Then-President Thabo Mbeki walked out of the room as an 11-year-old boy with AIDS addressed the crowd in response, pleading for treatment and understanding in a region where the epidemic was taking its harshest toll.

“Don't be afraid of us. We are all the same,” Nkosi Johnson said. He died the next year.

South Africa's official attitude to AIDS at that meeting in 2000 and for several years afterward set back the country so badly that more than 330,000 people died because the government withheld HIV drugs, a Harvard study found.

On Monday, the return of hundreds of AIDS researchers and activists to Durban will highlight how radically the country's outlook has changed.

South Africa now is a global proving ground for treatment and prevention, including a study of an experimental HIV vaccine set to begin later this year.

Today, the country says its HIV drug treatment program is the largest in the world. Life expectancy, which sank as the epidemic grew, rebounded from 57.1 years in 2009 to 62.9 years in 2014. And President Jacob Zuma has publicly tested for HIV to push back against stigma.

But South Africa still leads the world in infections, with 6.8 million people living with HIV. Only half receive treatment.

“The government is trying (its) best,” said Charity Mathe, who lives with dozens of mothers and children affected by HIV at Nkosi's Haven, a Johannesburg-based project named for the boy who challenged the president in 2000.

More solutions are needed, philanthropist Bill Gates warned an audience in the capital, Pretoria, on Sunday night. “If we fail to act, all the hard-earned gains made in HIV in sub-Saharan Africa over the last 15 years could be reversed.”

South Africa now wants to double the number of people getting treatment, part of a global goal to have 90 percent of infected people on treatment by 2020.

In the Johannesburg community of Alexandra, one project is taking on that challenge by trying to make drug delivery convenient.

What looks like ATM machines have been installed in a shopping center, ready for a rollout later this year. People will be able to walk up, insert their medical registration or speak via a video monitor with a pharmacy worker, select their prescription and pick up drugs that pop out.