Guinea-Bissau Halts US-Funded Hepatitis B & Autism Study

Guinea-Bissau has suspended a U.S.-funded study evaluating the timing of hepatitis B vaccinations for newborns, following ethical concerns and pressure from both the scientific community and U.S. Senators. The study, initially approved by the U.S. Centers for Disease Control and Prevention (CDC), aimed to compare administering the vaccine at birth versus the standard six-week timeframe.

The decision to halt the trial, February 18, 2026, comes after a previous suspension in January 2026 for ethical review. Critics raised concerns that the study design involved withholding a proven preventative measure – the hepatitis B vaccine – from a portion of newborns in a country with a high prevalence of the disease. The World Health Organization (WHO) Director-General, Tedros Ghebreyesus, previously stated the study was not ethical.

Foreign Minister João Bernardo Vieira announced the closure of the study on Tuesday, citing concerns expressed by the scientific community and U.S. Senators. “It will not take place, period,” he stated.

The $1.6 million study was funded under the purview of Robert F. Kennedy Jr., the current Secretary of the U.S. Department of Health and Human Services (HHS), and a long-time vaccine skeptic. The funding approval followed Kennedy’s reversal of the CDC’s recommendation for universal newborn hepatitis B vaccination in the United States.

Hepatitis B and the Risk to Infants

Hepatitis B is a viral infection that attacks the liver and can cause both acute and chronic disease. According to Johns Hopkins University, approximately 90% of infants exposed to hepatitis B at birth or within their first year of life develop a chronic infection. Of those chronically infected, 15% to 25% may die prematurely from liver failure or liver cancer.

Guinea-Bissau currently administers the hepatitis B vaccine at six weeks of age. Researchers involved in the suspended study argued that delaying vaccination leaves many infants vulnerable to infection, as mothers can transmit the virus to their babies during birth. The study aimed to determine if administering the vaccine at birth would provide earlier protection.

The Study Design and Ethical Debate

The proposed study, conducted by researchers from the Bandim Health Project in Guinea-Bissau (affiliated with the University of Southern Denmark), planned to enroll 14,000 newborns. Participants would have been randomly assigned to receive their first dose of the hepatitis B vaccine either at birth or at six weeks, mirroring the current practice. Researchers intended to examine “non-specific effects” of the vaccine, including potential impacts on skin conditions and neurodevelopment, including autism.

The ethical concerns centered on the potential risk to infants who would have been deliberately delayed in receiving a proven preventative measure. Critics argued that withholding the vaccine in a high-prevalence area was unethical, even for research purposes. The debate also highlighted broader questions about the appropriateness of conducting research in resource-limited settings where access to healthcare is already constrained.

Researchers Defend the Study’s Intent

Frederik Schaltz-Buchholzer, the principal investigator of the study, expressed regret that the debate had become politicized. “Everyone will be a loser if this trial is stopped, but confidence in vaccines and health research will suffer particularly,” he stated. He expressed hope that a revised study proposal could be accepted in the future.

The Bandim Health Project has a long-standing presence in Guinea-Bissau, and researchers emphasize their commitment to understanding the full impact of vaccines, both positive and negative. They argue that the study was designed to generate evidence that could inform vaccination policies and improve public health outcomes.

Political Context and Funding Implications

Robert F. Kennedy Jr. Has previously cited research from the Bandim Health Project to justify cuts to U.S. Funding for Gavi, the Vaccine Alliance, an organization that supports vaccine access in low-income countries. This connection further fueled concerns that the study was motivated by anti-vaccine sentiment rather than sound scientific principles.

As of February 18, 2026, a spokesperson for the U.S. CDC had not responded to a request for comment regarding the suspension of the study. The future of hepatitis B vaccination policy in Guinea-Bissau remains uncertain, but public health authorities have indicated plans to implement a universal birth-dose policy in 2027.