RFK Jr. Plan to Test a Vaccine in West African Babies Is Blocked NYT Par :Stephanie Nolen and Christina Jewett 22 janvier 2026 à 23:59 A planned U.S.-funded study of a hepatitis B vaccine drew widespread condemnation from researchers. Now the host country says it cannot proceed. © Rebecca Blackwell/Associated PressEach year thousands of babies born in Guinea-Bissau, one of the world’s least developed countries, are exposed to hepatitis B, a virus that can cause severe liver damage and cancer.