A health worker prepares a child to be administered the malaria vaccine R21/Matrix-M at the Health Centre in Yenagoa, Nigeria, Tuesday, Dec. 10, 2024. (AP Photo/Sunday Alamba)

A woman waits to have the malaria vaccine R21/Matrix-M administered to her children at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)

A health worker administers the malaria vaccine R21/Matrix-M to a child at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)

Women wait to have the malaria vaccine R21/Matrix-M administered to their children at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)

A child is weighed on a scale before he is administered the malaria vaccine R21/Matrix-M at the Health Centre in Yenagoa, Nigeria, Tuesday, Dec. 10, 2024. (AP Photo/Sunday Alamba)

A health worker administers the malaria vaccine R21/Matrix-M to a child at the Health Centre in Yenagoa, Nigeria, Tuesday, Dec. 10, 2024. (AP Photo/Sunday Alamba)

Women wait to have the malaria vaccine R21/Matrix-M administered to their children at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)

Health workers waits for children who will be administered the malaria vaccine R21/Matrix-M at the Health Centre in Yenagoa, Nigeria, Tuesday, Dec. 10, 2024. (AP Photo/Sunday Alamba)

A woman waits to have the malaria vaccine R21/Matrix-M administered to her child at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)

A woman waits for her child to be administered the malaria vaccine R21/Matrix-M at the comprehensive Health Centre in Agudama-Epie, in Yenagoa, Nigeria, Monday, Dec. 9, 2024. (AP Photo/Sunday Alamba)