UPDATE: The controversial hepatitis B vaccine trial backed by RFK Jr. will NOT proceed. Guinea-Bissau has formally rejected the proposed U.S.-funded study involving 14,000 newborns, following months of international criticism over its scientific justification and ethical implications. The trial would have randomly assigned half the infants to receive the hepatitis B vaccine at birth, while the remaining half would receive it at six weeks, consistent with the country’s existing vaccination schedule. The investigators wanted to examine possible “nonspecific effects” of vaccination, including health outcomes unrelated to hepatitis B infection. But there was a fundamental ethical problem. We already know that administering hepatitis B vaccine shortly after birth substantially reduces mother-to-child transmission. The WHO estimates that the birth dose prevents 70–95% of these infections. And approximately 90% of infants infected around birth develop chronic hepatitis B, placing them at lifelong risk of cirrhosis and liver cancer. The researchers argued that no child would receive less than the existing national standard of care. That distinction matters. But the WHO countered that resource constraints do not justify withholding a proven preventive intervention in a research experiment, particularly without a compelling scientific rationale. On October 16, Guinea-Bissau’s government formally rejected the study. Researchers subsequently confirmed that it would not proceed. No children had been enrolled. This is about something larger than RFK Jr. or any particular vaccine. Scientific curiosity is essential. Investigating unexpected effects of medical interventions is legitimate. But research involving human participants must satisfy ethical standards that extend beyond whether an interesting question remains unanswered. The burden is on investigators to demonstrate that a study’s scientific value justifies its risks—not on vulnerable participants to bear those risks simply because researchers want answers. That principle deserves defending, regardless of who funds the research.