New CDC Guidelines Could Leave Babies Vulnerable To Hepatitis B, Study Warns

Revised federal vaccination guidelines for hepatitis B could leave children at risk of contracting the liver-damaging virus from other family members, a new study warns.

Family members — not mothers — pose an active hepatitis B infection risk to more than half of kids with potential exposure to the virus, researchers reported Thursday at IDWeek, the joint annual meeting of America’s top infectious disease associations.

The findings run counter to updated guidance issued in January 2025 by the U.S. Centers for Disease Control and Prevention (CDC), which now recommends the hepatitis B vaccine only for babies whose mothers either carry the virus or haven’t been tested.

“A child can be exposed to hepatitis B from anyone with an active infection, not just their mother,” said lead researcher Dr. Karen Jacobson, an infectious diseases physician and research scientist at the Vaccine Study Center at the Kaiser Permanente Division of Research.

“No one knows the status of everyone a child may come into contact with, and vaccinating infants at birth protects against known and unknown potential sources of transmission,” she added in a news release.

Prior to the update, the CDC recommended that all babies receive the hepatitis B vaccine at birth, researchers said in background notes.

About 640,000 U.S. adults live with chronic hepatitis B, the researchers said. When infected early in life, 90% of infants will develop chronic hepatitis B, leaving them at risk for liver scarring and liver cancer as they grow older.

For the new study, researchers analyzed data on 158,000 children under 5 years of age living in 132,000 households in northern California.

More than 2,000 of the children were living in a household with a person who had active hepatitis B, creating a risk for potential infection. 

Hepatitis B can be transmitted after birth through contact with body fluids like blood, tears and saliva, and the virus can live on surfaces for up to a week, researchers said.

Among the exposed children, only 42% had a birth mother with hepatitis B infection. The rest (58%) were living with a family member who had active hepatitis B.

All of the kids born to a mother with hepatitis B had been vaccinated within seven days of birth, but only 94% of those living with an infected family member had been vaccinated.

Among children not exposed to hepatitis B in their homes, even fewer (87%) had been vaccinated.

“The hepatitis B vaccine is a safe and effective way to protect against HBV infection,” Jacobson said.

IDWeek is the joint annual meeting of the Infectious Diseases Society of America, the Society for Healthcare Epidemiology of America, the HIV Medicine Association and the Pediatric Infectious Diseases Society.

The meeting continues through Saturday in Washington, D.C.

Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.

More information

The U.S. Centers for Disease Control and Prevention has more on hepatitis B.

SOURCE: IDWeek, news release, Oct. 21, 2026