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High viral load, HBeAg positivity increased risk for mother-to-infant HBV transmission

Infants born to mothers with a high hepatitis B viral load, particularly those positive for hepatitis B e antigen, are at high risk for contracting hepatitis despite immunoprophylaxis, according to recent results.

Researchers evaluated 303 mother-infant pairs in which mothers tested positive for hepatitis B surface antigen (HBsAg). Maternal viral load and hepatitis B e antigen (HBeAg) status were determined, and children were tested for HBsAg at ages 4 to 8 months (n=250) and/or 1 to 3 years (n=53 for an initial test; n=183 for a follow-up test). All children received HBV vaccine within the first week of birth and at 1 and 6 months, with a 100% completion rate; children born to mothers who tested positive for HBeAg received hepatitis B immunoglobulin within 24 hours of birth.

HBeAg-positive mothers (81 cases) had higher viral loads than those who did not (7.4 ± 1.9 log₁₀ copies/mL vs. 2.7 ± 1.4 log₁₀ copies/mL; P<.0001 for difference). Chronic HBV infection was identified in 10 children, all born to HBeAg-positive mothers with high viral loads (range 6.5-9.5 log₁₀ copies/mL), and all with the same HBV genotypes and subtypes as their mothers.

Investigators identified a significant association between maternal viral load and a child’s risk for infection via multivariate analysis, after adjusting for factors including age; birth type; infant gender, weight and gestational age, and feeding practices (adjusted OR=3.49; 95% CI, 1.63-.7.48 per log₁₀ copy/mL increase). Predictive rates for maternally transmitted HBV infection were found to be statistically significant at 7 (6.6%; P=.033), 8 (14.6%; P=.001), and 9 (27.7%; P<.001) log₁₀ copies/mL.

“High maternal viral load is the most important factor causing maternally transmitted HBV infection, and is significantly correlated with maternal HBeAg status,” the researchers wrote. “Our predictive model including multiple risk factors showed that children with a maternal viral load above 107-108 copies/mL would have a significant risk of infection despite immunoprophylaxis. Our data provide important information for the rational design of future screening and intervention strategies to further reduce maternally transmitted HBV infection.”