Children's HBV exposure shifts to household contacts as policy changes
A new study reveals most hepatitis B exposure in young children now comes from household contacts, not mothers.
A study of over 158,000 children under age 5 shows most HBV exposure now occurs through household contacts rather than birth mothers. The research, presented at IDWeek 2026, found 1.3% of these children lived in a household with a person who had active hepatitis B infection. Of the 2,024 exposed children, 58.2% were exposed via a nonmaternal household member.
Children exposed through their mothers accounted for 41.8% of cases. All children born to a mother with HBV were vaccinated within the first week of life. In contrast, 4.2% of children exposed to HBV by a nonmaternal contact were unvaccinated by age 30 days.
Vaccination coverage differences emerge
Children living with an infected household member had a vaccination rate of 93.5%. This was higher than the 86.7% rate among unexposed children. Yet testing rates revealed a significant gap. While 95% of infants exposed at birth were tested for HBV, only 3.6% of children exposed via a household contact received testing.
The profile of nonmaternal contacts differed from mothers. Their median age was 44, compared to 38 for maternal contacts. Also, 76.5% of these nonmaternal contacts were male.
Policy shift drives new exposure risks
This data arrives as vaccination policy changes. In December, the Advisory Committee on Immunization Practices voted to stop recommending a universal birth dose of the hepatitis B vaccine for infants born to mothers who test negative. The CDC changed its guidance in January 2025, now recommending a birth dose within 12 hours only for infants born to mothers who test positive or whose status is unknown.
Critics warn that skipping the universal birth dose could lead to preventable infections, liver cancers, and deaths. A modeling study suggested the proposed shared decision-making approach could increase chronic HBV infections by 83%. Karen Jacobson, an infectious disease physician and study co-author, offered context. "Transmission of hepatitis B to children from nonmaternal sources is currently quite rare in the U.S. due to the high vaccination rates," she said.
Understanding the transmission threat
The virus poses a persistent threat in homes. HBV can be transmitted after birth through contact with body fluids like blood, tears, and saliva. It can survive on environmental surfaces for up to a week. When infection occurs in infancy, 90% of cases develop into chronic hepatitis B. This chronic condition can cause lifelong complications including cirrhosis and liver cancer.
The study's 1.3% household exposure rate is likely an underestimate. Limitations include potential inaccurate addresses and the fact that household contacts with HBV might not have been members of the Kaiser Permanente Northern California system where the data was analyzed. The research included 158,169 children in 131,800 households as of June 2023.
Approximately 640,000 adults in the U.S. live with chronic hepatitis B. The new policy landscape, moving away from universal infant protection, places greater emphasis on understanding these household exposure pathways. The modeling study projects an 83% increase in chronic HBV infections under the new shared decision-making approach.
