In a video address, the health secretary said the United States would no longer donate to Gavi, the vaccine agency. The organization rejected his claims.

The police fired tear gas at demonstrators who were expressing anger at the government over growing economic hardship and a lack of accountability for killings at earlier rallies.

A new drug that gives almost complete protection against the virus was to be administered across Africa this year. Now, much of the funding for that effort is gone.

The administration is pushing nations around the world, including ones at war, to take people expelled by the U.S. government who are not citizens of those countries.

The administration has gutted agencies like U.S.A.I.D., and President Trump has denigrated their work as wasteful and rife with fraud. His views on humanitarian assistance have seesawed since he entered political life.