Guinea-Bissau has suspended a clinical trial of a hepatitis B vaccine in newborns pending an ethical review[1]. The study, led by the CDC-supported Bandim Health Project, was scheduled to begin in January 2026 and enroll 14,000 newborns, only half of whom would have received the vaccine at birth[2]. The World Health Organization recommends that hepatitis B vaccine be given at birth to prevent infection during delivery[2]. In Guinea-Bissau, the vaccine is currently administered at 6 weeks of age, but the country plans to implement a universal policy of newborn vaccination from 2027-28[1]. The study has been criticized as unethical because hepatitis B is widespread in Guinea-Bissau - approximately 90% of newborns exposed to the disease at birth develop a chronic infection that can lead to cirrhosis and liver cancer[1]. The Guinean National Ethics Committee approved the study in November 2025 and funds were provided in December 2025[3]. The National Regulatory Authority and the National Ethics Committee of Guinea-Bissau must provide recommendations before a final decision on the continuation of the study[1].