Background Hepatitis B virus infection is a serious health concern in China. The National Immunization Program has implemented universal hepatitis B vaccination for infants for over two decades. The serological characteristics of hepatitis B virus and the causes of infections among adult blood donors born after 2002 remain undetermined. Methods Qualified blood donors born between 2002 and 2006 from Guangdong were screened for antibodies against hepatitis B surface antigen (anti-HBs) and hepatitis B core antigen (anti-HBc). Donations positive for HBsAg were subjected to various tests, including HBV serological markers, quantitative PCR (qPCR), and nested PCR, to further analyze the molecular characteristics of HBV DNA. Notable mutations were identified through comparison with HBV reference sequences obtained from blood donors. Results This study enrolled 5,487 blood donors with complete results for anti-HBs and anti-HBc testing. Overall, the prevalence of anti-HBs was 47.73% in males and 46.16% in females, while the prevalence of anti-HBc was 10.58% in males and 12.79% in females. Among blood donors born between 2002 and 2006, the prevalence of anti-HBs declined progressively with more recent birth years, decreasing from 54.55% to 40.23%, while the prevalence of anti-HBc remained relatively stable at around 11%. The prevalence (56.54%) and level of anti-HBs in the Pearl River Delta were significantly higher than those in the eastern, western, and northern regions of Guangdong (P0.001). Quantitative analysis revealed that anti-HBs levels were significantly higher in the anti-HBc+ cohort than in the anti-HBc- group. Furthermore, whole genome sequences genotyping of 72 HBsAg+ samples revealed that 75% (54/72) were genotype B and 25% (18/72) were genotype C. Nine HBV-related point mutations were detected, including four previously reported variants and five novel substitutions. Additionally, six insertions/deletions were observed in genotype B/C. All these mutations were mapped to critical functional regions within the PreS1, Core, X, and S genes. Conclusion Only 47.13% of young adults vaccinated at birth under the national immunization program retained protective antibodies at the time of testing, indicating this age group vulnerable to HBV infection. This decline has consequently increased the risk of breakthrough infection, necessitating booster vaccination among young adults in Guangdong.
Liao et al. (Wed,) studied this question.