Not Just Moms Who Put Unvaccinated Infants at Risk of Hepatitis B, Study Shows

WASHINGTON — For young children, exposure to hepatitis B virus (HBV) mostly came from someone other than their mother in the household, according to a retrospective cohort study.

Among over 158,000 children younger than 5 years, 1.3% lived in a household that had a person with active HBV infection, with 58.2% of those children exposed via contacts who were not their mothers versus 41.8% who were exposed via their mothers, reported Karen Jacobson, MD, MPH, of the Kaiser Permanente Vaccine Study Center in Pleasanton, California, at the IDWeek annual meeting.

“Our findings show that even if it is possible to accurately identify every single maternal infection, this would not account for potential exposure to an infected father, grandparent, or another person living in the household — and of course anyone that they might come into close contact with outside the household,” Jacobson said during a press briefing before the meeting.

“Transmission of hepatitis B to children from nonmaternal sources is currently quite rare in the U.S. due to the high vaccination rates,” she noted. “But if rates decrease, more infants could be at risk.”

A universal birth dose of the HBV vaccine protects babies from such household exposures.

Despite that, the CDC’s Advisory Committee on Immunization Practices (ACIP) in December voted to reverse more than three decades of U.S. vaccine policy and stop recommending a universal dose of the HBV vaccine at birth for infants born to mothers who test negative for hepatitis B surface antigen (HBsAg).

ACIP continues to recommend that infants born to mothers who test positive or who are unscreened for HBsAg receive a birth dose within 12 hours of delivery. When a mother tests negative, however, ACIP called for shared decision-making about HBV vaccination birth doses.

Critics have warned that skipping the universal birth dose will cause preventable acute and chronic HBV infections, liver cancers, and deaths, and add millions of dollars in additional healthcare costs. A recent modeling study suggested that the proposed shared decision-making approach would increase chronic HBV infections by 83%.

In babies who don’t get a birth dose, ACIP recommended delaying the first dose of the three-dose series to at least age 2 months. But Jacobson’s study showed that 4.2% of children exposed to HBV by a nonmaternal household contact were unvaccinated by age 30 days — within that 2-month window.

ACIP’s latest recommendations “are really focusing on that maternal exposure, and I think it’s important that other sources of potential exposure are not ignored,” Jacobson said.

While 95% of birth-exposed infants were tested for HBV, only 3.6% of children with household exposures were tested. All birth-exposed children were vaccinated within 7 days of birth.

Children with household exposure were more likely (93.5%) than those who weren’t exposed (86.7%) to be vaccinated. “This suggests that some families or healthcare providers did recognize the potential risk associated with household exposure,” Jacobson pointed out.

Jacobson and team analyzed laboratory and vaccination data through March for children younger than 5 years who were members of Kaiser Permanente Northern California (KPNC). Children were linked via addresses to birth mothers and households with at least one other KPNC member.

The 158,169 children lived in 131,800 households, of which 1,689 had a person with active HBV. Nonmaternal household contacts were older (median age 44) than maternal contacts (median age 38), and 76.5% were male.

Because children aren’t routinely screened for HBV, Jacobson’s team couldn’t determine whether any of the household-exposed children developed HBV infections.

The study’s 1.3% household exposure rate may sound low, Jacobson noted, but “it’s important to remember that this is likely an underestimate,” and “when infection occurs in infancy, it’s highly likely to result in chronic infection with lifelong sequelae.”

Study limitations included potential inaccurate addresses and underestimates if household contacts with HBV weren’t KPNC members.