Preventing Vertical Transmission of Hepatitis B

Mary Beth Nierengarten

May 27, 2014

A community program of prenatal screening for chronic hepatitis B virus (HBV) and use of neonatal immunoprophylaxis for infants born to HBV-positive women appears highly effective in preventing perinatal transmission, investigators report in a study published online May 26 in the Annals of Internal Medicine.

Immunoprophylaxis was particularly effective in women with e antigen–negative chronic HBV and those with a viral load. In these women, the extremely low risk for transmission found after immunoprophylaxis suggests that additional interventions to further reduce vertical transmission are not needed.

Although current guidelines by the Centers for Disease Control and Prevention (CDC) recommend prenatal HBV screening and neonatal immunoprophylaxis for infants whose mothers are HBV-positive, the effectiveness of this protocol is unknown at the community level.

To fill this gap, Ai Kubo, PhD, from Kaiser Permanente Division of Research, Oakland, California, and colleagues conducted an observational study of mothers and infants tested and treated according to the CDC recommendations in Kaiser's HBV perinatal immunoprophylaxis program. Key endpoints for the study included transmission rates, maternal risk factors for HBV transmission, follow-up testing rates, and adherence to immunoprophylaxis.

The study included 4446 infants born between 1997 and 2010 to 3253 HBV-positive women.

The overall transmission rate was 0.75 per 100 births (Poisson 95% confidence interval [CI], 0.48 - 1.10). The infection rate per 100 births in e antigen–positive women was 3.37 (95% CI, 2.08 - 5.14); it was 0.04 (95% CI, 0.001 - 0.24) for e antigen–negative women.

The researchers measured viral load in a subset of women. Of those, 831 (90.9%) had low viral loads, defined as less than 5 × 107 IU/mL. The infection rate per 100 births among these women was 0, regardless of e antigen status. Among the 83 births to women with viral loads of 5 × 107 IU/mL or higher, the infection rate per 100 births was 3.61 (95% CI, 0. 75 - 10.56).

The lowest viral load associated with transmission in the study was 6.32 × 107 IU/mL.

"Our results suggest than an organized program with high rates of prenatal screening, detection, and immunoprophylaxis can effectively prevent vertical transmission of hepatitis B," the investigators state.

An important clinical implication of these results, according to the investigators, is that additional intervention after immunoprophylaxis is unlikely to further decrease vertical transmission in e antigen–negative women or those with low viral loads.

"Prenatal treatments, such as oral antiviral agents, are unlikely to be of additional benefit in this population and may cause harm," the investigators write, "even if used only for short periods, by inducing viral resistance or posttreatment hepatitis flares."

In addition, they emphasize, e antigen–positive women and those with higher viral loads (5 × 107 IU/mL or higher) had low but detectable transmission rates after neonatal immunoprophylaxis.

The authors note several study limitations including the potential difficulty of implementing this type of organized screening and tracking program in some settings.

The investigators conclude that more studies are warranted to assess the effectiveness of additional prophylaxis measures, such as antiviral treatment in late pregnancy.

Support for this study was provided by the Kaiser Permanente Community Benefit, the National Cancer Institute, the National Institutes of Health Office of Research on Women’s Health, and the National Center for Advancing Translational Sciences of the National Institutes of Health. The authors have disclosed no relevant financial relationships.

Ann Intern Med. Published online May 26, 2014. Abstract

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