Recent changes to federal hepatitis B vaccine guidance could lead to more lifelong infections in U.S. children, according to a modeling study led by Harvard Medical School researchers at Massachusetts General Hospital.
Before December 2025, the Centers for Disease Control and Prevention (CDC) recommended vaccinating all newborns within 24 hours of birth. In December 2025, the Advisory Committee on Immunization Practices (ACIP) recommended that parents of infants born to mothers who test negative for hepatitis B decide when and whether to give the vaccine, including the birth dose. In January 2026, the CDC shifted to recommending vaccination only for certain high-risk groups, with a “shared clinical decision-making” approach for other infants.
The research team modeled vaccination starting at age 2 months for those infants under both new approaches, simulating what would happen to one year’s worth of U.S. births — about 3.6 million babies — through age 20. Assuming half of families chose vaccination, chronic infections under the shared decision-making approach would rise from an estimated 255 to 467, an 83 percent increase. About 1.8 million young adults would reach age 20 unprotected against the virus, compared with 232,000 under universal birth vaccination.
Infants and young children who contract hepatitis B are at high risk of lifelong infection, which can lead to cirrhosis and liver cancer. Even a small rise in childhood infections “could have large clinical, public health, and economic effects,” said lead and corresponding author Amir Mohareb, HMS assistant professor of medicine at Mass General and an infectious disease physician and clinician-researcher at the Center for Global Health at Mass General Brigham.
The findings are projections from a computer model and depend on assumptions about how many families choose vaccination. They were published Oct. 20 in Annals of Internal Medicine.
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Authorship, funding, disclosures
Arthur Kim and Emily Hyle are co-senior authors on the study. Additional authors are Lakshmi Ganapathi, Caitlin Dugdale, Ruma Rajbhandari, Andrea Ciaranello, Anne Neilan, and Ravi Jhaveri.
This work was supported in part by the National Institute of Allergy and Infectious Diseases (K01AI166126), a James and Audrey Foster MGH Research Scholar Award, and the Harvard University Center for AIDS Research (P30 AI060354), which is supported by the following National Institutes of Health (NIH) Co-Funding and Participating Institutes and Centers: NIAID; the National Cancer Institute; the Eunice Kennedy Shriver National Institute of Child Health and Human Development; the National Institute of Dental and Craniofacial Research; the National Heart, Lung, and Blood Institute; the National Institute on Drug Abuse; the National Institute of Mental Health; the National Institute on Aging; the National Institute of Diabetes and Digestive and Kidney Diseases; the National Institute of Nursing Research; the National Institute on Minority Health and Health Disparities; the Fogarty International Center; and the Office of AIDS Research.
A full list of author disclosures can be found in the paper.
