Ending the practice of immunising all newborns against hepatitis B, as Health Secretary Robert F Kennedy Jr has recommended, would sharply increase the number of chronic infections and put more than half of Americans at risk of the disease by age 20, according to a study published last week, reports The New York Times.
For decades, doctors in the United States have administered the first dose of the hepatitis B vaccine to all babies within 24 hours of birth – and within 12 hours to infants whose mothers are known to be infected.
But last December, a panel of advisers chosen by Kennedy recommended that parents should decide whether, or when, infants should get the shot if they were born to mothers who test negative for hepatitis B. In those cases, the group said, parents should decide “no earlier than two months of age”.
Kennedy and his associates have argued that hepatitis B is primarily a sexually transmitted disease and that babies do not need the protection unless their mothers are infected. But the virus can be spread by people who do not know they have it, as well as by household objects used by an infected person.
In January, Kennedy proposed a new childhood vaccination schedule in which the vaccine would be offered under a shared clinical decision-making approach – that is, after consultation with a healthcare provider.
In March, a federal judge temporarily blocked the implementation of both the December and January recommendations, restoring the universal hepatitis B birth dose as the official guideline from the Centres for Disease Control and Prevention. But the lawsuit continues and the final ruling may yet defer hepatitis B vaccination to two months of age or later.
“Overturning a longstanding immunisation practice warranted evidence, and so that was the motivation to study this,” said Dr Amir Mohareb, an infectious diseases physician at Massachusetts General Hospital and Harvard Medical School who led the study.
Mohareb and his colleagues modelled the potential impact of changing hepatitis B vaccination policy on the estimated 3.6m infants born in a single year. Immunising babies at two months old rather than at birth would increase chronic hepatitis B infections acquired by 20 by 19%, from an average of 255 cases per year to 303, the study found.
Switching to a shared decision-making policy would increase the number of chronic infections by 83%, to an average of 467 cases, and would result in more than 50% of children born each year entering adulthood susceptible to infection.
The findings were published in the journal Annals of Internal Medicine.
The Department of Health and Human Services did not provide a comment on the results of the study or its implications.
The results are broadly consistent with those from two other studies published in April in the journal JAMA Paediatrics. One found that delaying vaccination until two months old would lead to $16.4 m in added medical cost for infants born in one year. The second study found that preventing the increase in infections would require doctors to screen hundreds of thousands more pregnant women for hepatitis B than they currently do.
Together, the three studies underscore the idea that ending universal vaccination of newborns for hepatitis B would have grave consequences, said Dr Noele Nelson, an author on the economic impact study, who helped summarise the current guidelines for the vaccine.
“We really could be headed for increased chronic hepatitis B viral infections in the United States if we continue on this path,” she said.
The new study suggests that the increase in new cases per year might be small, at least at first. But infections would quickly accumulate each year, greatly increasing the risk for anyone who is unvaccinated, noted Dr José Romero, who led the Advisory Committee on Immunisation Practices from June 2018 to August 2021, and the committee’s hepatitis B work group from 2017 to 2018.
In June 2025, Kennedy fired all 17 members of the ACIP and replaced them with new ones who mostly agreed with his scepticism of vaccines. Before making their recommendation to defer the birth dose, those members should have considered data from modelling studies to gauge the consequences, Romero said.
“In fact, a decision as monumental as this would have merited multiple discussions among ACIP members when I was on the committee,” he said, and the potential for harm would have stopped them from recommending a change: “There’s no question in my mind that they would have said no.”
Only about half of cases before 1991, when routine vaccination of newborns for hepatitis B began, were a result of transmission from an infected mother.
“If you think about how many children are in day care with other children, how many children are cared for by uncles, aunts and other guardians, it’s certainly a possibility to acquire the infection from those others,” Mohareb said. “The virus could be spread by something as simple as cutting the nails, because there could be microscopic blood on a nail clipper,” he added.
Some experts said they were concerned about making vaccines available only after a healthcare provider assesses a patient’s risk. That approach is appropriate when there’s uncertainty in the balance of risks and benefits from a vaccine, Nelson said.
But in the case of hepatitis B, there is no evidence of harm from the shots at any age. On the other hand, patients may not disclose risky behaviours, such as promiscuity or drug use, and doctors in turn may not screen for the disease because of constraints on time or resources.
“Informed consent is always part of the process, and the ability to ask questions also is always part of the process,” Nelson said. “But shared clinical decision-making makes it look as if the recommendation is weaker, and therefore is not followed as closely.”
Study details
Projected Effect of 2026 Federal Changes to the Childhood Immunisation Schedule on Chronic Hepatitis B Virus Infections in the United States
Amir Mohareb, Lakshmi Ganapathi, Caitlin Dugdale et al.
Published in Annals of Internal Medicine on 20 October 2026
Abstract
Background
The United States recently proposed changes to the recommendations for childhood hepatitis B virus (HBV) vaccination.
Objective
To project the effect of vaccine policy changes, if fully implemented, on chronic HBV infections.
Design
Markov cohort state transition model of perinatal and childhood HBV infection.
Data Sources
Published data on maternal HBV prevalence (0.4%) and hepatitis B surface antigen testing (99.5% sensitivity), childhood vaccine completion (universal birth-dose strategy: 91.1%; deferred strategy: 87.1%; shared decision-making strategy: 50.0%), and age-stratified risk for chronic HBV infection.
Target Population
One-year birth cohort of US-born infants (n = 3.6 million).
Time Horizon
20 years.
Intervention
Universal birth-dose vaccination, deferred (2-month) vaccination, and vaccination through shared decision making.
Outcome Measures
Numbers with chronic HBV infection and susceptibility to HBV, with 95% uncertainty intervals (UIs) derived from probabilistic sensitivity analysis.
Results of Base-Case Analysis
Compared with the universal birth-dose strategy (255 childhood infections [95% UI, 130 to 530]), the deferred and shared decision-making strategies would increase chronic HBV infections in the 2026 birth cohort by 19% to 303 (95% UI, 155 to 610) and by 83% to 467 (95% UI, 209 to 1032), respectively. These strategies would also increase the number of HBV-susceptible people at year 20 (474 000 and 1 806 000) compared with the universal birth-dose strategy (232 000).
Results of Sensitivity Analysis
In a scenario with lower vaccine coverage (84.5%) and higher HBV prevalence (maternal prevalence of 0.72% and higher risk for horizontal infection), chronic HBV infections would increase to 1700 and 2192, respectively, with the deferred and shared decision-making strategies.
Limitation
Uncertainty in horizontal HBV infection risk.
Conclusion
Proposed policy changes for vaccination through shared decision making are projected to result in an 83% increase in childhood HBV infections, and between 50% and 70% of children entering adulthood annually would be susceptible to HBV infection. Policymakers should reimplement recommendations for universal birth-dose vaccination.
See more from MedicalBrief archives:
CDC ends decades-long hepatitis jab policy
US to end recommendations for newborns’ hepatitis B jabs
Experts oppose Kennedy’s hepatitis B jab theories
Experts call for hepatitis B birth-dose vaccine