Estimates of the global prevalence of occult hepatitis B virus infection in population under 18 years old: a systematic review and meta-analysis

OBJECTIVE: Occult hepatitis B virus infection (OBI) is defined by the presence of hepatitis B virus (HBV) DNA, while HBsAg (Hepatitis B surface antigen) remains undetectable. The infectivity of OBI and its potential ability to contribute to cirrhosis and hepatocellular carcinoma has been reported, with infection in children potentially leading to more severe outcomes. However, the global prevalence and disease burden remain unclear, and this study aimed to assess the prevalence of OBI in population under 18 years old. METHODS: We conducted a systematic literature search in PubMed, Embase, Scopus, Cochrane Library, China National Knowledge Infrastructure, and Wanfang Chinese databases for articles evaluating OBI in population under 18 years old. The prevalence of OBI was pooled after quality assessment. RESULTS: A total of 49 studies was included, allowing a meta-analysis of 1,070,526 HBsAg-negative individuals. Data from 28 and 25 studies were extracted for analysis of the high- and low-risk population, respectively. The overall prevalence of OBI in population <= 18 years old was 2.1% [95% confidence interval (CI): 0.9%-3.8%] and 9.7% (95% CI: 4.9%-15.8%) in the low- and high-risk population, respectively. In the subgroup analysis of the high-risk population, the OBI prevalence in the African, Eastern Mediterranean, and Western Pacific regions was 21.5% (95% CI: 0.0%-69.9%), 26.8% (95% CI: 13.0%-43.4%), and 4.3% (95% CI: 1.5%-8.2%), respectively. The OBI prevalence was 6.3% (95% CI: 2.7%-11.1%) in children born to mothers infected with HBV, 20.5% (95% CI: 0.0%-66.6%) in population infected with HIV or HCV, and 37.8% (95% CI: 30.8%-45.1%) in population who received blood transfusion. The OBI prevalence was 6.0% (95% CI: 2.4%-11.0%) in participants whose mothers were infected with HBV and vaccinated with hepatitis B vaccine (HepB) and HBIG, 7.1% (95% CI: 0.0%-22.9%) in participants only vaccinated with HepB. CONCLUSION: The global prevalence of OBI among individuals under 18 years old, particularly in high-risk population, cannot be neglected. Given the stealthy transmission of OBI and its potential for serious clinical outcomes, OBI in population younger than 18 years old should be emphasized as a global health issue.