The $1.6 million study, funded under the purview of Robert F. Kennedy Jr., a known vaccine skeptic and the secretary of the U.S. Department of Health and Human Services (HHS), sparked widespread criticism due to ethical concerns. Critics argued that the study involved withholding proven hepatitis B vaccines from newborns in a country with a high prevalence of the disease.

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. According to the World Health Organization (WHO), the virus is most commonly spread from mother to child during birth and delivery, as well as through contact with infected blood or other body fluids. Vaccination is a highly effective method of preventing hepatitis B infection, particularly when administered shortly after birth.

The ethical concerns centered on the potential harm to newborns who were not vaccinated as part of the study. Withholding a proven preventative measure in a population at high risk of infection raised questions about the study's adherence to established ethical guidelines for medical research.

"It’s of importance for Africa CDC to have evidence that can be translated in policy, but this has to be done within the norm," Boum told journalists, emphasizing the importance of ethical considerations in research.

The cancellation of the study raises questions about the oversight of US-funded research projects in Africa and the role of individuals with known biases in the funding and approval process. The Africa CDC's decision to halt the study underscores the importance of adhering to ethical standards and prioritizing the well-being of participants in medical research. The implications of this cancellation for future hepatitis B prevention efforts in Guinea-Bissau remain to be seen.