The pharmaceutical company Merck said on Friday that it would license seven generic drugmakers to produce a low-cost version of a new monthly H.I.V. prevention pill that has generated significant optimism about the role it could play in ending the H.I.V. epidemic.
The decision is intended to make stockpiles of the drug immediately available in developing countries if clinical trial results next year live up to expectations for the pill.
The company’s announcement on Friday comes as a major international AIDS conference begins in Rio de Janeiro, against a backdrop of disappointment with limited progress on cutting H.I.V. infection rates.
The new drug, alimatravir, is a pill taken once a month for what is called pre-exposure prophylaxis, or PrEP. It is being tested in a late-stage trial involving young women in three sub-Saharan African countries, and in a separate trial in countries across Latin America, Asia, Europe and Africa that involves transgender people and men who have sex with men.
There were 1.2 million new H.I.V. infections in 2025, according to UNAIDS, a United Nations agency. More tools to prevent infection are available, but they are not reaching many of the world’s most vulnerable people. Slow but steady progress toward the goal of lowering H.I.V. transmission rates was derailed over the past 18 months by sharp reductions in funding from the United States and other major donor countries.
A recent analysis by the Clinton Health Access Initiative found a 42 percent decline in the number of people who were started on oral PrEP in 2025 in 10 sub-Saharan African and Asian countries with high rates of H.I.V. infection, compared to the year before.
Merck’s deal will allow generics to be produced for 129 low- and middle-income countries. The company said it would also manufacture a bridge supply to be sold to those countries at a no-profit price, before the generic product comes to market and gets regulatory approval. The company would not disclose the price.
Merck will give a royalty-free license to four generic companies in India, and to three in sub-Saharan Africa — drugmakers in Uganda, Kenya and South Africa — in a boost for regional manufacturing efforts. That has been an African Union priority since the continent was largely shut out of access to Covid vaccines until a year after the rest of the world.
Because production of alimatravir uses a small quantity of its active pharmaceutical ingredient, and because it is a standard oral formulation, companies could produce it profitably at scale and sell it to national health systems for as little as $5 per person per year.
The timing of Merck’s announcement, coming well ahead of final clinical trial results, is unusual, and appears to be an effort to avoid problems that have dogged the introduction of other PrEP products.
Advocates for H.I.V. treatment and care are advising Merck on how to ensure access to the drug, if the trial results show it works.
“Our engagement with pharma has always been fights, but it is amazing to sit with them and have them say, ‘We are learning from the other products,’” said Kenneth Mwehonge, the executive director of the Coalition for Health Promotion and Social Development in Uganda.
Still, he added: “It all sounds good for now, but we will wait to see how it’s put to action.”
H.I.V. researchers expect alimatravir to provide a high level of protection against infection, because the molecule at the heart of the drug is closely related to another highly effective H.I.V. medication. Alimatravir also provided high rates of protection in studies with nonhuman primates, said Dr. Nina Russell, who oversees investment in H.I.V. drug development for the Gates Foundation.
“We have more optimism about this than is typical,” she said. “It could be pretty transformative.”
The Gates Foundation has invested $100 million into the late-stage trial for the drug, and expects to invest another $51 million into the efforts to make it rapidly accessible, she said.
In studies, the drug has provided protection from H.I.V. starting just one hour after a person takes it, and has offered about a weeklong grace period of protection if people have forgotten to take their next pill at the start of the month, said Gregg Szabo, a senior vice president at Merck.
A daily PrEP pill has been widely adopted in high-income countries in communities of people at higher risk of H.I.V. infection, such as gay men. But it has not proven to be a viable option for many people in developing countries.
Long-acting PrEP is seen as key to ending the African H.I.V. epidemic in particular. Ten countries across the continent have recently made available an injectable drug, lenacapavir, that provides close to 100 percent protection from H.I.V. for six months.
But as the funding to assist African governments with the purchase and distribution of new H.I.V. products has contracted sharply since early 2025, the hope invested in lenacapavir has dimmed. Fragile health systems may struggle to deliver it or to keep people coming back to get it.
Alimatravir, at just 12 pills a year, would be much easier to deliver than an injectable, and could be distributed outside clinics, and in venues such as hair salons and high schools, Mr. Mwehonge said. A young woman, he said, could pick up a year’s supply at the same time she gets birth control pills.
The generics deal covers all of Africa; Asian countries with large populations of people with H.I.V., such as Cambodia and Thailand; and some of Latin America. It does not include Brazil, where there are 55,000 new infections each year, or Colombia, Mexico, Peru and Chile, all of which are sites for clinical trials of the drug.
Chirfi Guindo, Merck’s executive vice president for strategic access, policy and communications, said the company was in talks with the Oswaldo Cruz Foundation, a Brazilian public health research institute that manufactures drugs, about a supply deal for Latin America.
“The intent is to find ways to really make alimatravir available in Brazil and in the region of Latin America as rapidly as possible in a way that is affordable,” he said.
Access to new products in Latin America is a persistent challenge. The region’s middle-income countries are typically left out of licensing deals, although the population most vulnerable to H.I.V. relies on public health systems that struggle to afford innovative products.
More than seven months after lenacapavir began to be given out in Africa, it is still not available in Brazil. Gilead, the company that makes lenacapavir, did not include Brazil or Mexico, which were part of the key clinical trial that showed the drug provided near-total protection from H.I.V., in the licenses it gave generics makers.
Dr. Alexandre Padilha, Brazil’s minister of health, said that Brazil remained shut out after more than a year of negotiating with Gilead.
The country has offered to pay Gilead $400 per patient per year, which is 10 times the price of generic lenacapavir in the countries covered by Gilead’s voluntary licenses, he said. That price reflects significant advance purchase commitments from the United States government and other funders, which brought the price down. Gilead charges $28,000 per patient in the United States.
Dr. Padilha said that although Brazil has an effective PrEP program, with 150,000 people taking oral PrEP daily, those are mostly men who have sex with men. There is a clear need for other products to serve other high-risk groups, such as sex workers, who would likely find the discretion of a twice-a-year injection appealing. But the public health system cannot afford it at the price Gilead wants Brazil to pay, he said.
“Innovation without access is injustice,” he said. “We cannot afford the stratospheric prices they propose, in a public system.”
Ashleigh Koss, a Gilead spokeswoman, said the company was committed to rapidly expanding access to lenacapavir.
“Discussions regarding access in Latin America and the Caribbean are taking place through multiple pathways, including ongoing regional discussions with the Pan American Health Organization,” she said, referring to the regional branch of the World Health Organization, which organizes pooled purchasing of drugs.
