Seroprevalence of hepatitis B virus infection among children and adolescents in Singapore, 2008-2010

Virtual monitoring for stable chronic hepatitis B patients does not reduce adherence to medications: A randomised controlled study

INTRODUCTION

Chronic hepatitis B (CHB) remains common in endemic regions, causing significant healthcare burden. Patients with CHB may need to be adherent to nucleoside analogue (NA) for a long period of time to prevent complications. This study aims to investigate the safety, efficacy and patient experience of a virtual monitoring clinic (VMC) in monitoring stable patients taking NA for CHB.

METHODS

Patients on NA and regular follow-up were randomised to either VMC alternating with doctors' clinic visit or to a control group in which they continued standard follow-up by doctors. Therapy adherence was measured by medication possession ratio (MPR) for NA therapy, incidence of virological breakthrough and hepatocellular carcinoma (HCC) development at two years of follow-up. Patient acceptance was measured on a Likert scale of 1-10.

RESULTS

A total 192 patients completed follow-up: 94 and 98 patients in the VMC and control groups, respectively. Mean age was 60.6 ± 10.8 years, with 95.3% Chinese ethnicity and 64.1% males. Age, gender, race, educational, employment and financial status were similar in both groups. Upon study completion, the majority of patients - 76 (80.9%) in VMC group and 74 (75.5%) in control group - had MPR ≥0.8; 88.8% were satisfied and rated VMC better than a traditional follow-up clinic with doctors only. More than 85% of patients rated ≥8/10 on the Likert scale for VMC, and preferred VMC over traditional clinic visits. Clinical outcomes observed were HCC development in one (1.1%) in the VMC group and four (4.1%) in the control group (p = 0.369). Two (2.1%) and one (1.0%) virological breakthroughs were observed in the VMC and control groups, respectively (p = 0.615). No incidence of HCC or abnormal blood tests were missed in the VMC arm.

DISCUSSION

VMC is a viable and safe clinical model for monitoring stable CHB patients on NA therapy without compromising patients' adherence to medications and is preferred by patients.

Hepatitis B vaccine development and implementation

Vaccination against hepatitis B is the most effective strategy to control HBV infection. The first licensed hepatitis B vaccine was developed by the purification of hepatitis B surface antigen (HBsAg) from plasma of asymptomatic HBsAg carriers. Then, the recombinant DNA technology enabled the development of recombinant hepatitis B vaccine. A series of three doses vaccine can elicit long-term protection more than 30 y. Concurrent use of hepatitis B immunoglobulin and hepatitis B vaccine has substantially reduced the mother-to-child transmission of HBV, nearly zero infection in children of carrier mother with negative hepatitis B e antigen (HBeAg) and 5-10% infection in children of HBeAg-positive mothers. By the end of 2018, 189 countries adopted universal hepatitis B vaccination program, which has dramatically reduced the global prevalence of HBsAg in children <5 y of age, from 4.7% in the prevaccine era to 1.3% in 2015. However, the implementation of universal hepatitis B vaccination in some regions is suboptimal and timely birth dose vaccine is not routinely administered in more than half of newborn infants. Optimal worldwide universal hepatitis B vaccination requires more efforts to overcome the social and economic challenges.

Seroprevalence of vaccine-preventable diseases among children and adolescents in Singapore: Results from the National Paediatric Seroprevalence Survey 2018

OBJECTIVES

The Ministry of Health (MOH), Singapore, conducted the National Paediatric Seroprevalence Survey 2018 (NPSS 2018) to estimate the latest immunity levels against measles, rubella, varicella, diphtheria, tetanus and hepatitis B, and the seroprevalence of chronic hepatitis B virus (HBV) carriage in children and adolescents in Singapore.

METHODS

The survey involved prospective collection of residual sera from 1,200 children and adolescents aged 1-17 years in two public acute hospitals. Enzyme-linked immunosorbent assays (EIA) or plague reduction neutralisation tests (PRNT) were used to determine the seroprevalence of the vaccine-preventable diseases.

RESULTS

Overall prevalence of measles and rubella antibodies among Singaporean children and adolescents aged 1-17 years were 98.2% (95% CI: 91.2-98.8%) and 94.8% (95% CI: 93.4-95.9%) respectively. 97.1% (95% CI: 96.0-97.9%) of subjects had at least basic protection against diphtheria, while 89.3% (95% CI: 87.5-91.0%) were protected against tetanus. The prevalence of chronic HBV carriage was 0.4% (95% CI: 0.2-1.0%), while 45.7% (95% CI: 42.9-48.5%) were immune against HBV. The seroprevalence for varicella antibodies was 52.9% (95% CI: 50.1-55.7%). Concordance between vaccination status and seroprevalence was observed for measles, rubella, diphtheria and tetanus.

CONCLUSION

Singapore's children and adolescents are well-protected against measles, rubella, diphtheria and tetanus. Continual efforts in ensuring high vaccination coverage should be sustained.

Factors Associated with Hepatitis B and C Co-Infection among HIV-Infected Patients in Singapore, 2006-2017

Co-infection of hepatitis B virus (HBV) and hepatitis C virus (HCV) with human immunodeficiency virus (HIV) is associated with increased risk of hepatic complications and mortality. A retrospective study to estimate the proportion of HBV and HCV co-infections in Singapore was conducted using a clinical database. We included 3065 patients who were seen under the Clinical HIV Programme at the largest referral centre for HIV care between 2006 and 2017 and were tested for both HBV and HCV. Factors associated with HIV-HBV and HIV-HCV co-infections were determined using logistic regressions. The majority (86.3%) of HIV-infected patients were mono-infected, while 7.2% were co-infected with HBV, 6.0% with HCV, and 0.5% were co-infected with both HBV and HCV. The most common HCV genotype was GT1 (63%). Factors significantly associated with HBV co-infection in the multivariable model were: Aged 30–49 years and 50–69 years at HIV diagnosis, male gender, and HIV transmission through intravenous drug use (IDU). Independent factors associated with HCV co-infection were: Malay ethnicity, HIV transmission through IDU, and HIV diagnosis between 2006 and 2008. Behavioural risk factors such as IDU, as well as epidemiologic differences associated with co-infection, should inform further studies and interventions aimed at reducing viral hepatitis infection among HIV-infected individuals.

Revaccination against hepatitis B in late teenagers who received vaccination during infancy: Yes or no?

The significance of vaccination against hepatitis B during infancy is recognized worldwide, however, whether booster or revaccination after a period of time following the primary vaccination is required remains controversial. Recently, cross-sectional epidemiological surveys found that HBsAg prevalence in subjects born after the implementation of mass vaccination was increased with age, which was attributed to waning of anti-HBs over time. However, comprehensive analysis of the closely related cross-sectional surveys showed that the age-specific increased HBsAg prevalence was more likely associated with the carry-over of the infection occurred in early life, likely due to imperfect coverage of hepatitis B vaccination at the beginning of its introduction. Latest studies showed that booster response could be observed in the majority of individuals vaccinated 30 years ago. Moreover, confirmed breakthrough HBV infection with severe consequences in successfully vaccinated individuals is extremely rare. Thus far no compelling evidence has been acquired to support booster vaccination in adolescence. The uncertainty regarding the duration of protection of hepatitis B vaccination, especially beyond 30 years after the primary vaccination, merits a systematically designed study to follow the same cohort of participants longitudinally, which differs from the cross-sectional studies reported previously, can hopefully offer more direct evidence to help us to determine whether revaccination of hepatitis B vaccine is necessary.

Deciphering the epidemiology of hepatocellular carcinoma through the passage of time: A study of 1,401 patients across 3 decades

Hepatocellular carcinoma (HCC) is one of the most common and lethal cancers globally. With advances in therapy for chronic viral hepatitis, changing social circumstances, and increasing practice of HCC surveillance, the epidemiology of HCC is expected to change over time. We explored the temporal trends in HCC in Singapore, a multiethnic Asian country, over the last 3 decades. Patients with HCC were prospectively enrolled and stratified into two cohorts (C1, 1988‐2002; C2, 2003‐2016). Patient and tumor characteristics, management, and survival were compared between the two cohorts, and a survival census was performed on October 31, 2015. There were 1,401 patients, and the mean age at diagnosis of HCC for C1 and C2 was 60.1 and 63.5 years, respectively. Male patient preponderance decreased significantly, with the male to female ratio falling from 5.2:1 to 3.9:1 between C1 and C2. Hepatitis B, although still the predominant risk factor for HCC, showed a significant decline from C1 to C2 (76.5% to 68.2%), while the nonviral etiology increased significantly over the same period (14.4% versus 25.0%, respectively). Significantly more patients in C2 than C1 were diagnosed through surveillance (39.2% versus 11.3%, respectively) and had better physical performance (Eastern Cooperative Oncology Group 0, 62.1% versus 20.4%, respectively). While Child‐Pugh status was comparable, significantly more patients in C2 than C1 had early stage disease (Barcelona Clinic Liver Cancer 0‐A, 39.5% versus 7.4%, respectively), which translated into significantly higher median survival (18.6 months versus 3.8 months, respectively). Conclusion: Over the past 3 decades, hepatitis B‐related HCC has been decreasing while HCC due to nonviral etiology has been increasing significantly. Surveillance to diagnose early stage HCC is important in improving the outcome of HCC. (Hepatology Communications 2017;1:564–571)

Minimization of hepatitis B infection among children in Jiangsu, China, 12years after integration of hepatitis B vaccine into the expanded program on immunization

BACKGROUND

China has integrated hepatitis B vaccine into the Expanded Program on Immunization since 2002. We aimed to survey the seroprevalence of and immunity to hepatitis B virus (HBV) in children born from 2002 to 2014 in Jiangsu, China.

METHODS

Totally 3442 children (M:F=2072:1370) at the age of 7months to 12years (5.5±3.6), from five cities and rural areas across Jiangsu province, were enrolled. Blood samples were measured for HBV markers by ELISA and quantitative microparticle enzyme immunoassay. HBV DNA was tested by real-time PCR and S region was amplified by nested PCR.

RESULTS

Twelve (0.35%) children were positive for hepatitis B surface antigen (HBsAg) and 34 (0.99%) were HBsAg negative and positive for antibody against hepatitis B core antigen (anti-HBc). Totally 2542 (73.85%) children had anti-HBs levels ⩾10mIU/ml and 535 (15.54%) with 2-9.9mIU/ml. All 12 HBsAg-positive children had detectable HBV DNA with a mean level of 6.1±1.7logIU/ml (3.3-8.1logIU/ml); 8 were genotype C and 4 were genotype B. No mutation was detected in the a determinant of HBsAg. HBV DNA was not detected in all the 34 children with positive anti-HBc and negative HBsAg.

CONCLUSION

HBsAg prevalence among children in Jiangsu born after the introduction of universal vaccination against hepatitis B has significantly decreased. No mutation of S gene is associated with vaccine failure in the cohort of children.

Significance of hepatitis virus infection in the oncogenic initiation of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death worldwide. Chronic infection of hepatitis B virus (HBV) and/or hepatitis C virus (HCV) is a major risk factor in the development of the HCC, independently from excessive alcohol abuse and metabolic disease. Since the biology of HBV and HCV is different, their oncogenic effect may go through different mechanisms, direct and/or indirect. Viral hepatitis infection is associated with cellular inflammation, oxidative stress, and DNA damage, that may lead to subsequent hepatic injuries such as chronic hepatitis, fibrosis, cirrhosis, and finally HCC. Direct oncogenic properties of these viruses are related with their genotypic characteristics and the ability of viral proteins to interact with host proteins, thus altering the molecular pathways balance of the cells. In addition, the integration of HBV DNA, especially the gene S and X, in a particular site of the host genome can disrupt chromosomal stability and may activate various oncogenic mechanisms, including those in hematopoietic cells. Recently, several studies also had demonstrated that viral hepatitis could trigger the population of hepatic cancer stem cells. This review summarize available pre-clinical and clinical data in literature regarding oncogenic properties of HBV and HCV in the early initiation of HCC.

Limited benefit of hepatitis B immunoglobulin prophylaxis in children of hepatitis B e antigen-negative mothers

INTRODUCTION

In 2006, Singapore adopted the universal hepatitis B immunoglobulin (HBIg) policy. Since then, all infants of hepatitis B surface antigen (HBsAg)-positive mothers receive HBIg, irrespective of maternal hepatitis B e antigen (HBeAg) status. However, the benefits of HBIg for infants of HBeAg-negative mothers are unclear. We compared the vertical transmission rates among children of HBeAg-negative mothers who were given HBIg versus a retrospective cohort who were not given HBIg, to determine its protective effect.

METHODS

This observational study involved pregnant HBsAg-positive women seen at National University Hospital, Singapore, between June 2009 and December 2013. If the infants of these mothers completed the recommended vaccination schedule, they were recruited into the study, along with their older siblings. Serological testing for the children was performed three months after completion of the last dose of vaccine, and hepatitis B virus (HBV) surface gene sequencing was carried out if HBV DNA was detected.

RESULTS

A total of 111 infants and 47 siblings were recruited. 2 (1.5%) children were found to have vertical transmission despite receiving HBIg, while no incidences of vertical transmission were found among the historical controls who did not receive HBIg (p = 1.00).

CONCLUSION

The overall effectiveness of the hepatitis B vaccination programme for children of HBsAg-positive mothers was high, regardless of HBIg administration. The addition of HBIg did not appear to confer additional benefits, in terms of vertical transmission rate, among infants born to HBeAg-negative mothers.

Changing epidemiology of hepatocellular carcinoma in Asia

Hepatocellular carcinoma is a major problem in Asia because of the presence of multiple risk factors in the region such as endemicity of hepatitis B and significant contamination of foodstuff by aflatoxin in some areas. Another risk factor for HCC, chronic hepatitis C infection, in Asia is most significant in Japan, the only Asian country with more HCV than HBV-related hepatocellular carcinoma. As these risk factors can and are being modified by measures such as universal hepatitis B immunisation, successful treatment of HCV infections, reduction and improved surveillance of aflatoxin contamination of foodstuff, it is not surprising that the epidemiology of HCC in Asia is changing. All these are offset by the rising importance of NAFLD and NASH as chronic liver diseases and risk factors for HCC which contributes to the changing epidemiology of HCC in Asia.

Hepatitis B immunoprophylaxis failure and the presence of hepatitis B surface gene mutants in the affected children

Hepatitis B virus (HBV) infection is usually vertically transmitted from the mother to child during birth in Asian countries. Despite immunization, immunoprophylaxis failure is well-documented. The aim of the study was to study immunoprophylaxis failure rate in the cohort of infants delivered by chronic HBV-infected mothers and to determine risk factors for failure. This was an observational study involving chronic hepatitis B infected mothers seen at a tertiary care center in Singapore between June 2009 and December 2013. Infants born to these mothers were recruited after they had completed the recommended vaccination schedule. Serological testing for the children was performed 3 months after completion of the last dose of vaccine. HBV surface gene sequencing was carried out if HBV DNA was detectable in the children. Among the 161 mothers enrolled, most were HBeAg negative. HBeAg positive mothers were younger and had a significantly higher viral load (6.5 log) as compared to HBeAg negative mothers (1.35 log) (P < 0.001). Four children (2.6%) were found to have immunoprophylaxis failure. Two occurred in children delivered by mothers with extremely high viral load of more than 5 × 10(7)  IU/ml. HBV surface gene mutations were detected in most children (3 out of 4) with immunoprophylaxis failure. The overall effectiveness of the hepatitis B vaccination program was high. High maternal viral load and presence of surface gene mutants may be potential contributors.

Hepatitis B virus infection in children

For two decades, hepatitis B vaccine has been integrated into national routine childhood vaccination programs in almost all countries. The prevalence of HBsAg has decreased in children worldwide. However, there are children who miss the benefit of hepatitis B vaccine in some regions and countries. Long-term follow-up studies have revealed the clinical outcomes of chronic hepatitis B virus infection in children. A small percentage of chronically infected children develop liver cirrhosis and hepatocellular carcinoma. However, it is controversial who should be treated and when antiviral treatment should be initiated in children. Compared with adult studies, the data are insufficient to evaluate the pathogenesis of hepatitis B infection and the efficacy of antiviral treatment in childhood. New antiviral drugs have been approved for children and adults. Also, oral antiviral drugs are administered to pregnant women to reduce the hepatitis B virus mother-to-child transmission rate.

Seroepidemiology of hepatitis B virus infection among adults in Singapore: a 12-year review

We undertook a national hepatitis B seroprevalence study to assess the seroprevalence of hepatitis B virus (HBV) markers in the adult population in Singapore in 2010 and make comparisons with the seroprevalence in 1998 and 2004. The study involved residual sera from national health surveys conducted every six years since 1998. The tests for HBV markers were carried out using commercial chemiluminescent microparticle immunoassay. In 2010, the prevalence of hepatitis B surface antigen (HBsAg) among 3293 Singapore residents aged 18-79 years was 3.6% (95% confidence interval [CI] 2.9-4.2%). Hepatitis B e antigen (HBeAg) was detected in 4.2% of those who were HBsAg positive. About 22.5% (95% CI 21.1-23.9%) were positive for antibody to hepatitis B core antigen (anti-HBc). The overall population immunity to HBV, as determined by antibody to hepatitis B surface antigen (anti-HBs)≥ 10 mIU/mL, was 43.9% (95% CI 42.2-45.6%). Among young adults below 30 years of age, HBsAg prevalence (1.1%) was half that in 1998 and 2004, and in those positive for HBsAg, none was positive for HBeAg in 2010, compared to 20.8% in 1998 and 15.8% in 2004. In this age group, anti-HBc prevalence also decreased significantly from 22.1% in 2004 to 4.4% in 2010, while anti-HBs (≥ 10 mIU/mL) prevalence increased significantly from 27.9% in 1998 to 43.3% in 2010 (p<0.001). The national childhood HBV immunisation and catch-up programmes implemented in 1987 and 2001-2004, respectively, had a significant impact in reducing HBV infection and in raising the immunity of the adult population 18-29 years of age.