The pharmaceutical company that makes a once-a-day pill that protects users against HIV has agreed to donate enough medication to cover as many as 200,000 people for 11 years, the Trump administration announced Thursday.

Gilead Sciences, the maker of Truvada, will donate as many as 2.4 million bottles of the costly drug each year to the Centers for Disease Control and Prevention, which will distribute the medication to uninsured people at high risk of contracting HIV. A year’s supply of the pills, known as pre-exposure prophylaxis, or PrEP, costs more than $20,000.

The donation is part of President Trump’s initiative to reduce HIV transmission in the United States by 90 percent by 2030.

“The majority of Americans who are at risk and who could protect themselves with PrEP are still not receiving the medication,” Health and Human Services Secretary Alex Azar said in a statement. “This agreement will help close that gap substantially.”

The government strategy to curb the spread of HIV focuses on the small number of places where the virus is concentrated: the District of Columbia; Puerto Rico; 48 hotspot counties across the country and in the rural parts of seven Southern states. In 2017, the South had about 20,000 new HIV diagnoses, more than the rest of the country combined.

According to government data, the number of new HIV diagnoses in the United States began to plateau in 2013, to about 39,000 infections per year, following five years of significant declines.

Taken daily, PrEP is more than 90 percent effective at preventing sexual transmission of the virus and more than 70 percent effective at blocking it among people who inject street drugs and share needles. Only about 10 to 20 percent of the 1.1 million people considered at risk of contracting HIV are on PrEP. A disproportionate number of those not on medication are black and Latino men who have sex with other men.

The obstacles to getting those at risk on Truvada are many: Cost, general lack of access to medical care, stigma, lack of knowledge among physicians and difficulty adhering to a daily drug regimen.

Jesse Milan Jr., president and chief executive of AIDS United, hailed what he called a “tremendous announcement” from Gilead Sciences.

“It will make a great difference in the lives of hundreds of thousands of people, and it will be a tremendous step toward ending the epidemic,” he said.

Gilead has said there is no link between the drug donation and a dispute between the company and the government over a CDC patent for Truvada as a preventive drug. CDC holds the patent because, it says, use of the drug was devised by its scientists, who experimented on monkeys in government labs.

Gilead has openly rejected the validity of the government patent. It says the idea for PrEP was already known before government experiments.

The Washington Post reported on April 24 that the Justice Department had opened a review of the government patent, which could be a first step toward a patent infringement lawsuit.

Under Thursday’s agreement, Gilead will donate Truvada until its next-generation HIV preventive medication, Descovy, becomes available. It will then donate that drug until the agreement ends, after 11 years or when a generic version becomes available, whichever comes first.

Chris Rowland contributed to this report.