Results of a systematic review and meta-analysis published in The Lancet Gastroenterology & Hepatology found that a significant number of individuals were carriers of occult hepatitis B virus (HBV) infection, particularly those in high-risk populations and those residing in highly endemic regions.
Investigators from Imperial College London searched publication databases for studies published between 2010 and August 2019 that assessed occult HBV infection. A total of 375 studies were included in the meta-analysis. The DerSimonian-Laird random-effects model was used to calculate the pooled prevalence of occult HBV infection.
The included studies were conducted in the West Pacific (32%), Eastern Mediterranean (21%), Europe (19%), the Americas (12%), Southeast Asia (9%), and Africa (6%). The endemicity of occult HBV infection was determined on the basis of low (<2.00%), intermediate (2.00%-4.99%), and high (≥5.00%) hepatitis B surface antigen prevalence. Of the included studies, 50% had low, 21% had intermediate, and 28% had high occult HBV endemicity.
Overall, a total of 140,521,993 individuals were evaluated for occult HBV infection, of whom the median of the mean age across studies was 49 (IQR, 37-55) years, the median percentage of men was 62%, and most individuals were blood donors (>99%).
In the pooled analysis, the prevalence of occult HBV infection was 0.09% (95% CI, 0.07%-0.11%; I2, 99%) in serum or plasma samples (n=140,518,289), 2.1% (95% CI, 0.0%-10.1%; I2, 96%) in peripheral blood mononuclear cells (PBMCs; n=1106), and 34.8% (95% CI, 27.0%-43.0%; I2, 94%) in liver samples (n=2598). The mean viral load for positive individuals was 200 IU/mL. The HBV genotypes among individuals positive for the infection mirrored the known distribution of HBV genotypes observed in those who were positive for the Hepatitis B surface antigen.
In individuals who were blood donors, the positivity rate was 0.98% among those in highly endemic regions, 0.12% among those in intermediate endemic regions, and 0.06% among those in regions with low endemicity.
The investigators stratified individuals who were blood donors by disease risk. Results showed the prevalence of occult HBV infection among low-risk individuals was 5.1% for those in highly endemic regions, 1.5% for those in intermediate endemic regions, and 2.6% for those in regions with low endemicity. Among high-risk individuals, the prevalence of occult HBV infection was 12.0%, 5.2%, and 5.5% for those in regions with high, intermediate, and low endemicity, respectively. In individuals with advanced chronic liver disease, the prevalence of occult HBV infection was 8.9%, 13.6%, and 25.2% among those in regions with high, intermediate, and low endemicity, respectively.
Limitations were the relatively small number of included studies, the inability to stratify individuals with occult HBV infection by viral load concentration, and heterogeneity.
According to the investigators, “occult HBV infection is a particular problem in HBV-endemic areas and across high-risk groups worldwide, indicating the need for better access to occult HBV diagnosis.”
Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.
Im YR, Jagdish R, Leith D, et al. Prevalence of occult hepatitis B virus infection in adults: a systematic review and meta-analysis. Lancet Gastroenterol Hepatol. 2022;7(10):932-942. doi:10.1016/S2468-1253(22)00201-1