The World Health Organization (WHO) has voiced serious ethical and scientific concerns over a proposed randomized controlled trial (RCT) in Guinea-Bissau that would withhold the hepatitis B birth dose vaccine from some newborns.

In a statement issued in response to media queries, WHO reaffirmed that the hepatitis B birth dose vaccine is a proven, essential public health intervention that prevents life-threatening liver disease by blocking mother-to-child transmission at birth.

Used for more than three decades and included in the national immunization schedules of over 115 countries, the timely administration of the vaccine within 24 hours of birth is considered central to global hepatitis B elimination efforts.WHO said it is aware of the proposed trial in Guinea-Bissau and, based on publicly available information and expert consultations, has “significant concerns” about its scientific justification, ethical safeguards, and compliance with established research standards involving human participants.

At the heart of the agency’s concern is the study design, which reportedly includes a no-treatment control arm. WHO emphasized that the hepatitis B birth dose has a well-established safety record and prevents 70–95% of mother-to-child transmission cases.

“Withholding a proven lifesaving intervention exposes newborns to serious and potentially irreversible harm,” the agency noted, citing risks such as chronic hepatitis B infection, cirrhosis, and liver cancer.

According to WHO, placebo or no-treatment vaccine trials are ethically acceptable only when no proven intervention exists or when such a design is indispensable to answer a critical question about efficacy or safety. Based on available descriptions, neither condition appears to apply to the Guinea-Bissau study.

WHO further questioned the scientific necessity of the trial, stating that publicly available information does not appear to challenge the established efficacy of the birth dose. Instead, the protocol reportedly raises hypothetical safety concerns without credible evidence of a safety signal that would justify exposing newborns to additional risk.

The agency also warned that the single-blind, no-treatment-controlled design could introduce significant bias, limiting the reliability and policy relevance of the findings.

Importantly, WHO underscored that resource constraints cannot ethically justify withholding proven care in research settings. Ethical research standards require minimizing risk and ensuring a reasonable prospect of benefit for participants. From what has been publicly described, WHO said, the protocol does not appear to provide even minimum harm-reduction measures, such as screening pregnant women and vaccinating newborns known to be exposed.

“In its current form, and based on publicly available information, the trial is inconsistent with established ethical and scientific principles,” the agency stated.

WHO acknowledged that Guinea-Bissau has suspended the proposed study pending further technical review. The agency expressed readiness to support the country as it evaluates next steps and works toward accelerating the introduction of the hepatitis B birth dose vaccine.

Support efforts may include strengthening birth-dose delivery within 24 hours for both home and facility births, antenatal screening for hepatitis B surface antigen (HBsAg), improving cold-chain and last-mile logistics, training midwives and healthcare workers, and enhancing monitoring systems for coverage, timeliness, and vaccine safety.

Hepatitis B remains a major global health threat, causing hundreds of thousands of deaths each year. Transmission at birth is the most common pathway to lifelong infection, with approximately 90% of infants infected during childbirth becoming chronic carriers at high risk of developing cirrhosis and liver cancer.

In Guinea-Bissau, more than 12% of adults were estimated to be living with chronic hepatitis B as of 2022. Among children under five, infection prevalence stood at around 2% in 2020 — far above the global elimination target of 0.1% or lower.

The country formally decided in 2024 to introduce the hepatitis B birth dose into its national immunization schedule, with rollout planned by 2028. WHO said this policy decision underscores the vaccine’s value and reinforces the ethical imperative to ensure newborns receive timely protection.

The agency reiterated its commitment to working with national authorities, researchers, and global partners to ensure that all newborns — in Guinea-Bissau and worldwide — benefit from evidence-based protection against hepatitis B, and that research in this area meets the highest ethical and scientific standards.