Parenteral viral hepatitis among students in Da Nang, Vietnam, and insights into new hepatitis B virus genotype B classification.

This cross-sectional study estimated the prevalence of hepatitis B, C, D viruses among adults aged 18-22 years and assessed the impact of viral populations on the epidemiological trends in hepatitis virus transmission. A total of 568 students of Da Nang University were enrolled in the study in 2018. The prevalence of HBsAg, anti-HBs and anti-HBc was 4.2% (24/568), 30.4% (173/568), and 17.6% (100/568), respectively. Anti-HCV was found in 0.2% (1/568) of samples, and no participants tested positive for anti-HDV. HBV DNA was detected in all HBsAg-positive samples: 19 HBV isolates belonged to genotype B, and 5-to genotype C. Eight isolates carried immune escape mutations within the S protein, and one harbored three mutations (1762A > T / 1764G > A, 1858 T > C) in the precore/core region. Most of HBV isolates belonged to subgenotype B4, which is part of the Ba global recombinant group comprising subgenotypes B2, B4 and "quasi-B3", characterized by common recombination sites between positions 1731-1846 and 2200-2252. These findings highlight the high prevalence of HBV and insufficient herd immunity against HBV within this cohort, underscoring the urgent need to expand national HBV vaccination strategies. Widespread distribution of the Ba global recombinant group emphasizes the necessity to revise the current HBV taxonomy.