Mass General Brigham study: Hepatitis B vaccine delays could increase infections

A computer modeling study by researchers at Mass General Brigham, Massachusetts General Hospital, and Harvard Medical School suggests that changing the hepatitis B vaccination schedule for newborns could lead to a significant rise in chronic infections.

Using a Markov cohort model to simulate 3.6 million infants—representing approximately one year of U.S. births—the study projected that delaying the first dose until two months of age could increase chronic hepatitis B infections acquired by age 20 by approximately 19%. Furthermore, a “shared decision-making” approach, which aligns with proposed federal guidance, was projected to increase infections by about 83%.

The findings, published in Annals of Internal Medicine, indicate that under a shared decision-making scenario, more than 50% of children could enter adulthood vulnerable to the virus. The researchers concluded that universal birth vaccination remains the most effective strategy for preventing childhood infections and reducing long-term risks such as liver failure and liver cancer.