Horizontal Transmission of HBV Common in Endemic Areas

New research is beginning to shed light on the transmission route of hepatitis B virus (HBV) in endemic areas.

A team, led by Xiao-Qun, Zheng, Department of Clinical Laboratory, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, examined the prevalence and transmission route of HBV in China for both adult and pediatric patients.

Transmission Routes of HBV

While HBV is extremely common, the transmission route is not fully understood. However, in China there is an 18-year implementation of free HBV vaccines for pediatrics, which has greatly reduced the prevalence of the virus and could serve as a real-world model for assessing the pattern of HBV transmission.

In the cross-sectional study, the investigators examined data on HBV seromarkers between July 2019 and April 2020. Overall, they collected data from 53,371 patients aged 1-60 years in 4 areas from North to South in Eastern China.

Longitudinal Data

The investigators collected longitudinal data of HBV seromarkers between 2007 and 2020 from 177 adults in South China and analyzed the regional and age-specific changes in HBV seromarkers.

The results show significant increases in both positive rates of HBV surface antigen (HBsAg) between 3.44%-15.1% and antibodies against HBV core antigen (anti-HBc) from 7.6%-44.0% from North to South.

For adult patients included in the cohort, the positive rates of antibody against HBsAG (anti-HBs) and anti-HBc (+) remained at low levels in the North. However, there were increasing among individuals older than 12 years in the South despite higher positive rates of anti-HBs (+).

For pediatric patients, the anti-HBs (+) rates were relatively stable at approximately 60%, but the anti-HBc (+) rates increased significantly with age.

In addition, up to about 80% of the anti-HBs (+) adults in the South was anti-HBc (+), compared to 13.6% in the North.

The longitudinal cohort showed the anti-HBc (+) rate among adults in the South increased by 14.2% during the 10 year follow-up period.

“Horizontal transmission might be a common route in highly endemic areas, and may help to explain the high HBV exposure worldwide,” the authors wrote. “The risk of horizontal transmission among children without seroprotective anti-HBs should be notified in highly endemic areas.”

New Screening Reccomendations

Earlier this year, the US Centers for Disease Control and Prevention (CDC) released new guidelines for HBV vaccination, calling for universal HBV vaccination for all adults aged 19-59 years in the US.

The CDC said in the Morbidity and Mortality Weekly Report (MMWR) that the decision is based on 4 decades of safety, immunogenicity, and efficacy data on the HBV vaccine, but with suboptimal coverage in the US.

Last November, the Advisory Committee on Immunization Practices (ACIP) first made the recommendations for universal vaccinations within that age group, while removing the risk factor assessment previously in place to determine vaccine eligibility.

The reccomendations are the result of more than 2 years of work evaluating the incidence of hepatitis B, morbidity related to hepatitis B, mortality related to hepatitis B, and vaccine-related serious adverse events.

The study, “Horizontal transmission might be a common route of hepatitis B virus exposure in highly endemic areas,” was published online in the Journal of Medical Virology.