Paul Farmer is a professor at Harvard University and an infectious disease physician with the Brigham and Women’s Hospital in Boston. He co-founded Partners in Health.

A decade after the global AIDS response began in earnest, it’s worth asking whether the lessons learned will be sustained over time and used to avoid past mistakes when tackling new challenges.

One such challenge is chronic hepatitis C infection, which afflicts an estimated 170 million people worldwide. Since its discovery 25 years ago, hepatitis C has become the leading indication for liver transplant in the United States and a common cause of liver failure around the world. For some, however, it is about to become eminently curable.

When I trained as an infectious disease physician in the mid-1990s, I traveled frequently between Boston’s teaching hospitals and rural Haiti. AIDS had become a leading cause of death in both places but was rapidly declining in Boston while soaring in Haiti, as it was across Africa.

This divergence was thrown into relief at a 1996 AIDS conference where researchers presented data showing that combination antiretroviral therapy could transform HIV infection from a death sentence into a manageable chronic disease. The conference’s theme that year was “One World, One Hope.” A coalition of activists, noting the $15,000 annual cost of the lifesaving drugs and the lack of an international plan for ensuring access among those living in poverty, held up their own signs reading “One World, No Hope.”

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By 2000, more than 6 million people were dying in poor countries each year from HIV, tuberculosis and malaria — diseases for which effective therapeutics were available to those who could afford them. Here was a failure not of science but of delivery.

Thankfully, and in no small part because of the relentless efforts of AIDS activists, an abiding cynicism about the limits of an international response to these pandemics gave way to an unprecedented “delivery decade.” This was inaugurated in the early 2000s with the U.S. President’s Emergency Plan for AIDS Relief and the Global Fund to Fight AIDS, Tuberculosis and Malaria.

As I recounted in the New England Journal of Medicine in December, linking this funding to effective delivery mechanisms had profound effects in some of the world’s poorest and most disrupted places. By the end of 2012, almost 10 million patients in low- and middle-income countries were on antiretroviral therapy. In Haiti and Rwanda, AIDS-related mortality rates fell more sharply than in the United States after its introduction of antiretroviral therapy in the mid-1990s.

Despite such progress, much remains to be done. Nearly half of all people living with HIV who need treatment still don’t receive it. But the coupling of an equity plan with a commitment to building effective delivery systems surely ranks among the most important achievements in the history of medicine and public health.

Today, the world faces a “1996 moment” in the fight against hepatitis C.

As in 1996, highly effective new therapies are coming online. Regimens containing the new polymerase inhibitor sofosbuvir, in particular, have the potential to cure more than 90 percent of patients with common strains of the virus after just 12 to 24 weeks of once-daily pills. But is there a plan that can link funding to delivery for those living in poverty?

Sofosbuvir’s initial price has been set at $80,000 to $90,000 per 12-week course — about $1,000 per pill. Like those infected with HIV, 90 percent of hepatitis C patients live in low- and middle-income countries ; most would not earn $80,000 over the course of two lifetimes.

In the face of such numbers, it is tempting to give in to pessimism. “Poor countries could never afford these prices; the demand simply isn’t there,” some say. But when the share of those infected with hepatitis C reaches 1 in 40 people alive today, claims of weak demand are not credible. Such language is often code for ability to pay, not actual burden of disease. In many years practicing medicine, I have yet to meet a patient — rich or poor — with a treatable disease who doesn’t want to get better.

Drug prices are not immutable, and price is not the same as cost. Pharmacologists with Liverpool University recently analyzed manufacturing processes for new hepatitis C regimens and concluded that they could be sold at profit in poor countries for less than $500 per course. A recent pledge by Gilead, the developer of sofosbuvir, to work with generic pharmaceutical firms in India is a promising start, but it is just a start.

Precipitous drops in price are not unprecedented; in the delivery decade, innovative partnerships through financing mechanisms such as UNITAID led to declines of as much as 99 percent in the effective price of antiretroviral therapy for the world’s poorest.

Smart investments in accurate diagnosis and in effective therapy for hepatitis C could save millions of lives in the coming years, radically cut transmission and pave the way toward eradication of the virus. Or, we could choose to ignore the lessons of the AIDS response and stand by as outcomes improve solely among the fortunate few who enjoy ready access to the fruits of modern medicine. Divergence of outcomes occurs within nations and across them; they grow whenever innovation is not coupled with implementation among the most vulnerable.

But we live in one world. As infectious pathogens such as HIV and hepatitis remind us, our hopes are tied together more closely than we might imagine.