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.

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.

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.

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.

The prevalence of chronic hepatitis B virus (HBV) poses a significant threat to the lives of 257 million individuals globally, potentially resulting in severe outcomes such as liver cirrhosis or hepatocellular carcinoma. Among the existing preventive measures, yeast-derived vaccines have proven to be the most efficacious approach in combatting hepatitis B. Nonetheless, as scientific inquiries focus more on occult HBV infection (OBI) in vaccinated persons and the lingering risk of vertical transmission affecting 10-30 % of babies born to HBsAg-positive mothers, there is a growing apprehension regarding the inability of HBV vaccines to ensure complete immunity. This study aims to offer a more comprehensive understanding of the implications of widespread HBV vaccination initiatives on OBI while tackling the primary limitations associated with current vaccine formulations.

The exploration was conducted on PubMed, Scopus, and Web of Science databases to pinpoint research on OBI within vaccinated cohorts. A sum of 76 suitable studies was recognized.

Multiple studies have documented the occurrence of OBI in fully vaccinated individuals, including both the general population and high-risk groups, such as newborns born to HBsAg-positive mothers. Factors contributing to vaccine failures include low-level anti-HBs antibodies, high maternal viral loads in mother-to-child transmission cases, as well as the presence of vaccine escape mutants and heterologous HBV genotypes. However, further research is needed to precisely understand the impact of active immunization on the emergence of OBI in vaccinated populations. Nonetheless, it is apparent that the advancement of more effective HBV vaccines could potentially lead to the extinction of HBV.

Occult hepatitis B infection (OBI) is a globally prevalent infection, with its frequency being influenced by the prevalence of hepatitis B virus (HBV) infection in a particular geographic region, including Africa. OBI can be transmitted through blood transfusions and organ transplants and has been linked to the development of hepatocellular carcinoma (HCC). The associated HBV genotype influences the infection.

To highlight the genetic diversity and prevalence of OBI in Africa.

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and involved a comprehensive search on PubMed, Google Scholar, Science Direct, and African Journals Online for published studies on the prevalence and genetic diversity of OBI in Africa.

The synthesis included 83 articles, revealing that the prevalence of OBI varied between countries and population groups, with the highest prevalence being 90.9% in patients with hepatitis C virus infection and 38% in blood donors, indicating an increased risk of HBV transmission through blood transfusions. Cases of OBI reactivation have been reported following chemotherapy. Genotype D is the predominant, followed by genotypes A and E.

This review highlights the prevalence of OBI in Africa, which varies across countries and population groups. The study also demonstrates that genotype D is the most prevalent.

Occult HBV infection (OBI) is a specific form of hepatitis B virus (HBV) infection and has the possibility of developing into hepatocellular carcinoma (HCC) in adults. This study aimed to estimate the global prevalence of occult HBV infection in children and adolescents.

We systematically searched PubMed, Embase, Web of Science, and Cochrane databases for relevant studies on the prevalence of OBI in children and adolescents. Meta-analysis was performed using STATA 16 software.

Fifty studies were included. The overall prevalence of OBI in children and adolescents was 7.5% (95% CI: 0.050-0.103). In different risk populations, OBI prevalence was remarkably high in the HIV-infected population (24.2%, 95% CI: 0.000-0.788). The OBI prevalence was 0.8% (95% CI:0.000-0.029) in the healthy population, 3.8% (95% CI:0.012-0.074) in the general population, and 6.4% (95% CI: 0.021-0.124) in children born to HBsAg-positive mothers. Based on different serological profiles, the prevalence of OBI in HBsAg-negative and anti-HBc-positive patients was 6.6% (95% CI: 0.016-0.136), 3.0% (95% CI: 0.009-0.059) in HBsAg-negative and anti-HBc-negative patients, 4.6% (95% CI: 0.015-0.088) in HBsAg-negative and anti-HBs-positive patients, and 3.7% (95% CI: 0.001-0.102) in HBsAg-negative and anti-HBs-negative patients.

Despite HBV vaccination and hepatitis B immunoglobulin (HBIG), OBI is common in children and adolescents in high-risk groups.

Occult hepatitis B virus (HBV) infection (OBI) is a major public health problem. The clinical importance of OBI stems from the fact that it can be transmitted to healthy individuals at extremely low viral load levels. Additionally, immunosuppression has the potential to trigger viral replication, which can result in life-threatening liver decompensation. Despite several studies examining the prevalence of OBI, the pooled prevalence of OBI in Egypt remains unknown, particularly among blood donors and high-risk individuals, to whom intervention should be targeted.

A comprehensive literature search of the following databases was conducted from inception to October 2022 using the following keywords: occult hepatitis B virus infection or occult HBV infection or OBI and Egypt in MEDLINE [PubMed], Scopus, Google Scholar, and Web of Science. The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement. I-squared and Cochran's Q were used to measure the heterogeneity between the studies, and based on the random effects model, results were reported as proportions (%) with a 95% confidence interval (CI). Analyses of subgroup analyses were conducted based on the target population. Sensitivity analyses were conducted using the leave-one-out approach to test the robustness of the results.

A total of 50 studies with 62 estimations of OBI were included, 19 in patients who were HBsAg-negative and anti-HBc-positive and 43 in patients who were HBsAg-negative. The highest prevalence (41%) was among multi-transfused patients according to  studies that report occult hepatitis B virus prevalence in an HBsAg-negative population, while the pooled prevalence of OBI among patients on hemodialysis, patients with chronic hepatitis C infection, patients with hepatocellular carcinoma (HCC), and patients with liver cirrhosis was 17%, 10%, 24%, and 13%, respectively. On the other hand, among studies that report OBI prevalence in HBsAg-negative and anti-HBc-positive individuals, the pooled prevalence of OBI among blood donors, patients with chronic hepatitis C infection, and patients with HCC was 12%, 15%, and 31%, respectively. Also, the majority of studies examining the genetic background of OBI have found that genotype D is the most prevalent.

 This study highlights the high prevalence in OBI among blood donors and high-risk populations in Egypt. The implementation of HBV nucleic acid amplification testing (NAT) may increase the safety of blood transfusions by excluding all HBV DNA-positive donations. However, the cost-effectiveness of these tests should be investigated.

Occult hepatitis B (OBI) and C (OCI) infections lead to hepatic crises including cases of liver cirrhosis and even hepatocellular carcinoma (HCC). OBI and OCI also pose a significant problem of their transmissibility. This study aimed to assess the overall prevalence of OBI and OCI in the African continent, a region highly endemic for classical hepatitis B and C viruses.

For this systematic review and meta-analysis, we searched: PubMed, Web of Science, African Journal Online and African Index Medicus for published studies on the prevalence of OBI and OCI in Africa. Study selection and data extraction were performed by at least two independent investigators. Heterogeneity (I²) was assessed using the χ² test on the Cochran Q statistic and H parameters. Sources of heterogeneity were explored by subgroup analyses. This study was registered in PROSPERO, with reference number CRD42021252772.

We obtained 157 prevalence data for this meta-analysis, from 134 studies for OBI prevalence; 23 studies on OCI prevalence, and a single study on the OBI case fatality rate. The overall estimate for the prevalence of OBI was 14.8% [95% CI = 12.2-17.7] among 18579 participants. The prevalence of seronegative OBI and seropositive OBI was 7.4% [95% CI = 3.8-11.8] and 20.0% [95% CI = 15.3-25.1] respectively. The overall estimate for the prevalence of OCI was 10.7% [95% CI = 6.6-15.4] among 2865 participants. The pooled prevalence of seronegative OCI was estimated at 10.7% [95%CI = 4.8-18.3] and that of seropositive OCI at 14.4% [95%CI = 5.2-22.1]. In Sub-group analysis, patients with malignancies, chronic hepatitis C, and hemodialysis had a higher OCI prevalence. While those with malignancies, liver disorders, and HIV positive registered highest OBI prevalence.

This review shows a high prevalence of OBI and OCI in Africa, with variable prevalence between countries and population groups.

Overt and occult hepatitis B infection (HBI) among mothers and infants were investigated, and the effectiveness of vaccination against HBI was evaluated based on transmission types.

A hospital-based cohort was built with 2,734 mothers and 330 mother-infant pairs. Their demographic data were collected. Serological HBV markers, nested-PCR for HBV genes, viral load detection, and phylogenetic analysis were done.

The overall prevalence of HBI among mothers was 12.1% (330/2,734), with 10.4% for the overt type and 1.8% for the occult type. In 330 out of 1,650 (20%) mother-infant pairs, the overall, type-I (from overt mother to overt infant), type-II (from overt mother to occult infant), and type-Ⅲ (from occult mother to occult infant) transmissions were 1.9% (1/54), 5.6% (3/54) and 0.0% (0/7). The refinement of HBI classification improved the estimate of vaccine effectiveness against HBI from 74.4%-80.9% to 94.4%, which was more prominent for type-II. One mother-infant pair with type-II transmission shared nearly identical complete sequences. However, the high rate of lost-to-follow-up could not be ignored.

During the transition period, HBV is mainly transmitted from the overt type of HBI mother to infant. Intensive prenatal screening for mothers is vital.

Despite access to efficient hepatitis B virus (HBV) vaccine and universal immunization schedules, HBV infection remains a global health concern. HBV infection has decreased by this program. Nevertheless, breakthrough infections occur due to generation of occult HBV infection (OBI) and surface gene mutants in the immunized population. We aimed to determine the presence of OBI in a population born after initiation of nationwide HBV vaccination in Tehran, Iran. A HBV mass vaccination schedule was launched in Iran in 1993. For this study, we enrolled 1120 cases younger than 24 years. ELISA was applied to evaluate the presence of HBsAg, anti-HBs and anti-HBc. HBV-DNA presence was determined in all HBsAg-negative cases using nested polymerase chain reaction. The prevalence of HBsAg, anti-HBc and anti-HBs was 0.1, 0.54 and 39.9% respectively. Out of 6 anti-HBc-positive individuals, 4 cases also had anti-HBs. One case revealed HBsAg co-existence and the other one showed isolated anti-HBc. HBV-DNA was not detected in HBsAg-negative specimens. A very low prevalence of HBsAg and isolated anti-HBc was observed and no occult HBV infection was detected. It seems that evasion mutants are not a potential threat for HBV universal immunization efficacy in the vaccinated population.

Present study aimed to systematically review and quantitatively synthesize published data about the prevalence of Hepatitis B Virus (HBV) infection among high risk groups in Iran.

Determining true burden of Hepatitis B Virus (HBV) infection among high-risk groups relies on knowledge of occurrence measures such as prevalence rate. There is no conclusive and comprehensive data regarding to prevalence of HBV infection among high risk groups in Iran.

Relevant studies were searched in PubMed, Scopus, Web of Knowledge and local databases. In addition, reference lists of relevant studies were searched manually. Two independent authors reviewed the eligibility of retrieved studies and extracted the required data. Studies reporting HBV infection among high risk groups were included in the meta-analysis using random effects models. Meta regression and sub-group analysis were considered as additional analyses.

The initial search yielded 566 citations. After the primary screen, 37 studies were selected for review. Meta-analysis results showed that pooled prevalence of HBV infection among high risk groups in Iran was 4.8% (95% confidence interval: 3.6%-6.1%), with the highest prevalence among in prisoners (5%; 3%-6%), and in central regions of Iran (7%; 4%-11%). Year of study may affect the observed heterogeneity in the estimated prevalence of HBV infection among injection drug users (IDUs) and prisoners.

Our results indicate that prevalence of HBV infection among high risk groups was seemingly high in Iran. Health policy decision makers should be aware of prevalence of HBV infection among different high risk groups and in different regions of Iran.

Health Care Workers (HCWs) are at a high risk of needle stick injuries and HBV infection in Egypt; this problem is further aggravated by low Hepatitis B (HB) vaccination coverage. Limited data are available on the prevalence of HBV infection in Egyptian HCWs. In this study, we aimed to assess the HBV infection rate and genotypes among Egyptian HCWs.

Five hundred and sixty-four (564) HCWs were included. Of them, 258 (45.74%) were health care providers and 306 (54.25%) were non-health care providers. All HCWs completed both the study questionnaires and provided a blood sample for HBV testing. Indeed, all HCWs were tested for Hepatitis B surface antigen (HBsAg) and antibody to Hepatitis B core antigen (anti-HBc), by enzyme-linked immunosorbent assay. HBVDNA was checked for HCWs who tested positive for HBsAg and/or anti-HBc, by nested Polymerase Chain Reaction (PCR). HBVDNA positive HCWs were further subjected to HBV genotyping.

The mean age of included HCWs was 33.0 ± 9.8 years, of whom 319 (56.56%) were males. The mean duration of health care work was 9.3 ± 6.7 years. The frequency of HBsAg and anti-HBc were 1.4%, and 24.5%, respectively. Old age and prolonged duration of health care work were significantly associated with anti-HBc seropositivity. Among 140 HCWs positive for HBsAg and/or anti-HBc, 14 (10 %) had positive HBVDNA by PCR. HBV/E (n = 7), HBV/D (n = 3) and co-infection with E and D (n = 4) genotypes were detected.

Egyptian HCWs have a significantly high rate of HBV exposure. The detection of HBV/E genotype among Egyptian HCWs suggests prevalent transmission of HBV/E among Egyptian populations.

The emerging evidence of the potentially clinical importance of occult hepatitis B virus (HBV) infection (OBI) increases the interest in this topic. OBI may impact in several clinical contexts, which include the possible transmission of the infection, the contribution to liver disease progression, the development of hepatocellular carcinoma, and the risk of reactivation. There are several articles that have published on OBI in Egyptian populations. A review of MEDLINE database was undertaken for relevant articles to clarify the epidemiology of OBI in Egypt. HBV genotype D is the only detectable genotype among Egyptian OBI patients. Higher rates of OBI reported among Egyptian chronic HCV, hemodialysis, children with malignant disorders, and cryptogenic liver disease patients. There is an evidence of OBI reactivation after treatment with chemotherapy. The available data suggested that screening for OBI must be a routine practice in these groups of patients. Further studies needed for better understand of the epidemiology of OBI among Egyptian young generations after the era of hepatitis B vaccination.

The prevalence of occult Hepatitis B virus (HBV) infection in children was considerably varied from 0.1-64% in different reports. In this study we aimed to investigate the prevalence of occult HBV infection among the children born to mothers with positive hepatitis B surface antigen (HBsAg) in Jiangsu, China. Serum samples were collected from 210 children of 207 mothers with positive HBsAg. HBV serological markers were detected by ELISA and HBV DNA was detected by nested PCR. Homology comparison of HBV sequences recovered from the child and mother was used to define the infection. Three children (1.43%) were positive for HBsAg, in whom the HBV pre S and S gene sequence in each child was identical to that in her mother. Of the 207 HBsAg-negative children, nine displayed HBV DNA positive by two nested PCR assays using primers derived from S and C genes. However, the sequence alignment showed that the sequences in each child were considerably different from those in his/her mother. Therefore, the sequences amplified from the children were very likely resultant from the cross-contaminations. Furthermore, the nine children with 'positive HBV DNA' were all negative for anti-HBc, and one had anti-HBs 3.42 mIU/ml and eight others had anti-HBs from 72 to >1000 mIU/ml, indicating that the nine children were less likely infected with HBV. Therefore, none of the 207 HBsAg-negative children of HBV-infected mothers was found to have occult HBV infection. We conclude that the prevalence of occult HBV infection in vaccinated children born to HBsAg positive mothers should be extremely low. We recommend that homology comparison of sequences recovered from the child and mother be used to define the occult HBV infection in children born to HBV infected mothers.