A simulation suggests replacing the routine hepatitis B birth dose with parent-clinician discussions could leave millions of young people unprotected and substantially increase chronic infections.
A new modelling study suggests that changing the hepatitis B birth dose from a routine offer to a discussion between parents and clinicians could materially weaken protection for children born in the US. The analysis, published in Annals of Internal Medicine and reported by ABC News and TIME, projected that chronic hepatitis B infections among children could rise by 83% over 20 years under a shared decision-making approach, compared with a universal newborn dose. If the first shot were simply pushed back to two months, the model estimated a 19% increase.
The researchers, based at Massachusetts General Hospital and Harvard Medical School, used a Markov model to follow a hypothetical cohort of 3.6 million babies born in 2026 through age 20. Their projections suggest that a policy built around individual discussions rather than a standard birth dose would leave far more young adults without protection, with roughly 1.8 million unvaccinated at age 20 in that scenario, compared with about 474,000 if the first dose were delayed until two months and about 232,000 under a universal birth dose.
The study is a simulation, not a count of actual infections, and its authors acknowledged that the results depend heavily on assumptions about vaccine uptake. TIME reported that if only about 26% of infants received the vaccine at two months, projected chronic infections rose by 225%. The model also indicated that infections passed from mother to baby could climb if infants born to women who test positive, or whose hepatitis B status is unknown, were less likely to receive prompt vaccination.
That concern comes against a backdrop of shifting federal guidance. In December 2025, the Centres for Disease Control and Prevention moved away from its long-standing universal birth-dose recommendation for babies born to women who test negative, opting instead for shared clinical decision-making. The CDC still says infants whose mothers test positive for hepatitis B, or whose status is unknown, should receive the vaccine within 12 hours of birth. In March, a federal judge in Massachusetts stayed the votes of the CDC’s vaccine advisory committee, and the agency’s website now says all infants should receive the hepatitis B vaccine, according to ABC News. The American Academy of Pediatrics continues to recommend that babies get the first dose within 24 hours of birth.
Doctors worry that more ambiguous language can change parental behaviour. Speaking to ABC News, Stanford paediatrician Alok Patel said that when a recommendation shifts from “every baby” to “Let’s discuss it,” many families may hear that the shot is optional. The underlying risk is real: the CDC says infants infected with hepatitis B have about a 90% chance of developing a chronic infection, which can lead to liver disease and liver cancer later in life. For families expecting a baby, the practical advice remains straightforward: confirm the prenatal hepatitis B test, ask whether the hospital offers the birth dose, and keep a record of every vaccination. The vaccine is available through the Vaccines for Children programme for eligible uninsured and underinsured children.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
