New Study Warns of Hepatitis B Vulnerability for Millions Due to Shifting Vaccine Recommendations

Changes to federal hepatitis B vaccination recommendations could result in more childhood infections and leave up to 1.8 million young adults vulnerable to the virus, according to a new study.

In late 2025, the Centers for Disease Control and Prevention (CDC) removed the universal hepatitis B vaccination recommendation for newborns. While these changes, along with others made under the Trump administration, have since been paused due to legal action, health experts are raising concerns about the potential long-term impact.

"These findings show why policy makers should re-implement recommendations for universal hepatitis B vaccination at birth," said corresponding author Dr. Amir Mohareb, an infectious disease physician and clinician researcher at Mass General Brigham.

Hepatitis B is a viral infection that attacks the liver and can cause short-term illness or a lifelong infection. Symptoms can include nausea, abdominal pain, and jaundice, though many infected individuals have no symptoms. The virus spreads through contact with infected blood and other bodily fluids. Infants are particularly vulnerable; approximately 90% of babies infected around the time of birth develop chronic hepatitis B.

Chronic hepatitis B can lead to serious complications, including liver damage and liver cancer. "The hepatitis B vaccine can prevent potentially life-threatening chronic liver disease, which can lead to liver cancer," said Dr. Alok Patel, clinical associate professor of pediatrics at Stanford. "Since we started vaccinating at birth in 1991, infant infections have dropped by a reported 99%."

To assess the potential impact of changing recommendations, researchers from Mass General Brigham utilized a computer model to track a hypothetical group of 3.6 million babies born in the U.S. in 2026 through their first 20 years of life. The study, published in the Annals of Internal Medicine, compared three vaccination approaches for babies born to mothers who test negative for hepatitis B:

• Universal birth dose: All newborns receive their first dose shortly after birth.
• Delayed dose: The first dose is administered at least 2 months of age.
• Shared clinical decision-making: Parents and healthcare providers discuss whether and when to vaccinate, rather than routinely recommending it at birth.

The model estimated that delaying vaccination until 2 months could increase chronic hepatitis B infections by 19% over 20 years, while the shared decision-making approach could increase infections by 83% compared to the universal birth dose. The study predicted that approximately 232,000 children could remain vulnerable to hepatitis B infection by age 20 under the universal birth dose approach. This number increased to 474,000 with a delayed dose and 1.8 million under the shared decision-making approach. These figures represent individuals susceptible to infection, not those who have already developed the disease.

"We found that, even under the most optimistic conditions, the new recommendations could increase childhood hepatitis B infections by more than 80% and would result in more than half of children being susceptible to hepatitis B infection as they enter adulthood," Mohareb stated.

Researchers also warned that if high-risk babies—those born to mothers who test positive for the virus or whose status is unknown—were less likely to receive the vaccine, perinatal infections could double or triple in 20 years compared to maintaining the universal recommendation. The study authors emphasized that these figures are estimates from a simulation.

In December 2025, the CDC changed its longstanding recommendation, allowing parents of babies born to mothers who test negative for hepatitis B to decide with their healthcare provider whether to vaccinate at birth or delay the series. However, babies born to mothers with hepatitis B or unknown status are still recommended to receive the vaccine within 12 hours of birth.

In March, a federal judge in Massachusetts issued a stay on all votes taken by the CDC's vaccine advisory committee, including the removal of the universal recommendation for the hepatitis B shot at birth. Currently, the CDC's website still states that all infants should receive the hepatitis B vaccine.

Responding to a request for comment, the Department of Health and Human Services pointed to a statement from Secretary Robert F. Kennedy Jr. on X, which read in part, "I reject the idea that respecting parents’ choices means abandoning children’s health. Under my leadership, HHS puts informed consent, individual medical circumstances, and conversations between parents and doctors at the center of health decisions."

The American Academy of Pediatrics continues to recommend that newborns receive their first hepatitis B vaccine dose within 24 hours of birth, followed by additional doses. Some physicians worry that the shift in federal guidance has created confusion, potentially leading to fewer vaccinations.

"When a recommendation shifts from 'every baby' to 'Let's discuss it,' a lot of families hear 'optional' or 'Maybe it was never that important,'" Patel said. Physicians and public health specialists underscore the vaccine's importance, even for babies born to mothers who test negative for hepatitis B, as children can encounter the virus through infected caregivers. Delaying the first dose, they warn, could also make it harder for some children to complete the recommended vaccine series.

"When parents fall off schedule or we lose them to follow-up, vaccination rates are far more likely to decline," Patel noted.

Another concern is that hepatitis B can remain undetected for years, with serious complications developing decades later. "[If] even a small percentage of new babies go without receiving the hepatitis B vaccine ... we could potentially have many more preventable cases of chronic liver disease and liver cancer," Patel added. "Even a small increase in childhood [hepatitis B virus] infections could have large clinical, public health and economic effects," Mohareb concluded.