Thanks to funding from the Pershing Square Foundation, the Bluebell Foundation and the U.S. Center for Disease Control and Prevention (CDC), researchers at the Bandim Health Project are now able to initiate a randomized controlled trial of the hepatitis B vaccine at birth in Guinea-Bissau. There is a unique window of opportunity, because the Guinean Ministry of Health has decided to implement a universal hepatitis B vaccine policy for newborns starting in 2027. Until then, the team will randomize newborns to receive the hepatitis B vaccine at birth (the future policy) or no hepatitis B vaccine at birth (the current policy). All children will receive the recommended BCG and OPV vaccines, irrespective of allocation. The children will be monitored for overall health outcomes. The hepatitis B vaccine at birth has never been tested on a large scale for its overall health effects, so it is unknown whether the vaccine has non-specific health effects. The trial team is extremely grateful to the donors for supporting this evaluation of a widely used vaccine, which will be the first and likely the only one of its kind. The trial was approved by the Guinean National Ethics Committee in November 2025 and will begin in early 2026.