The US is purchasing enough doses of a new twice-a-year HIV prevention shot to share with up to two million people in poor countries by 2028, the State Department announced on Thursday.

Gilead Sciences had already announced it would sell that supply of the protective drug lenacapvir at no profit for use in low- and middle-income countries that are hard-hit by HIV. The question was who would buy and distribute them after the Trump administration slashed foreign aid earlier this year – forcing closures of health clinics and disrupting HIV testing and care in many countries.

Under Thursday’s move, the US will purchase the doses under the PEPFAR programme and work with governments in hard-hit countries on how to distribute them. The priority will be to protect pregnant or breastfeeding women, said Jeremy Lewin, a State Department senior official.

Lewin said the program will be a collaboration with the Global Fund, another international program that funds HIV treatment and prevention efforts but wouldn’t disclose how much the US was investing.

“We’re hoping, with the Global Fund, to help two million people get on the medication over the next three years but could potentially see more,” he said.

There are more than 30,000 new HIV infections in the US every year and 1.2 million people are living with the virus. Worldwide there are 1.3 million new infections annually and nearly 40 million people living with the virus.

Many experts say lenacapavir is the most powerful option yet for what’s called PrEP – using preventive medicines to guard against sexually transmitted HIV. Unlike daily pills that people may forget, each lenacapavir shot offers protection for six months. In two ground-breaking studies with people at high risk, it nearly eliminated new infections.

The drug already has been approved for use in the US and Europe.

In March, the head of the UN Aids agency urged the Trump administration and Gilead to make the preventive shots available worldwide for millions.

Gilead has signed agreements with generic drug makers to produce low-cost versions of the shot for poor countries, mostly in Africa, Southeast Asia and the Caribbean. The doses provided at-cost for up to two million people in those countries was intended to be a stopgap until the generics are available.

• An AP report