JOHANNESBURG (AP) — Just a week had remained before scientists in South Africa were to begin clinical trials of an HIV vaccine, and hopes were high for another step toward limiting one of history’s deadliest pandemics. Then the email arrived.

Stop all work, it said. The United States under the Trump administration was withdrawing all its funding.

The news devastated the researchers, who live and work in a region where more people live with HIV than anywhere else in the world. Their research project, called BRILLIANT, was meant to be the latest to draw on the region’s genetic diversity and deep expertise in the hope of benefiting people everywhere.

But the $46 million from the U.S. for the project was disappearing, part of the dismantling of foreign aid by the world’s biggest donor earlier this year as President Donald Trump announced a focus on priorities at home.