New Vaccine Guidelines Could Lead to Hepatitis B Surge, Study Warns

A new study published in Annals of Internal Medicine indicates that revised recommendations for the hepatitis B vaccine could lead to a substantial rise in chronic hepatitis B cases among children in the United States. The research utilized computer modeling to simulate infection rates over the first 20 years of life for a cohort of newborns.

The U.S. has recommended routine hepatitis B vaccination for infants since 1991, with guidance specifying the first dose within 24 hours of birth. However, in December 2025, the Centers for Disease Control and Prevention (CDC) introduced a change for infants born to mothers who test negative for the virus. The new guidance suggests a shared decision-making model, allowing parents and clinicians to decide on the timing of the first dose, which could be given either shortly after birth or no earlier than two months of age. For infants born to mothers who test positive or whose status is unknown, the CDC continues to recommend a dose soon after birth.

Modeling the Impact

The study simulated outcomes for 3.6 million U.S. infants born in a single year under various scenarios. Researchers found that if only about 26% of infants receive the vaccine—an estimated uptake under the shared decision-making model—chronic hepatitis B cases could increase by 225% compared to the previous guidelines. If the first dose is delayed until two months of age and only 75% of infants receive it, the model predicted a 19% increase in chronic cases.

Dr. Amir Mohareb, an infectious-disease researcher at Harvard Medical School and Massachusetts General Hospital and an author of the study, stated that the research aims to provide evidence for the ongoing conversation about the potential impact of these changes. He noted that the simulation's findings, projected year after year, could result in thousands of new infections, potentially leading to lifelong chronic illness, increased cancer rates, and significant healthcare costs.

Mohareb emphasized that decades of clinical trials have already established the efficacy of the current vaccination approach, suggesting that further experimentation is unnecessary and that the benefits of established medical progress should be maintained.