A prospective and open-label study for the efficacy and safety of telbivudine in pregnancy for the prevention of perinatal transmission of hepatitis B virus infection

Role of HBsAg levels in guiding hepatitis B virus prophylaxis in pregnancy: Insights from a multi-ethnic cohort

Pregnant mothers with chronic hepatitis B infection (CHB) need peri-partum antiviral prophylaxis (PAP) to reduce the risk of mother-to-child-transmission. Currently, PAP is recommended in those with high viral load (VL) that is, HBV DNA >200,000 IU/mL. Quantitative hepatitis B surface antigen (qHBsAg) >10,000 IU/mL, a cut-off derived primarily from hepatitis B e-antigen (HBeAg) positive antenatal cohorts in Chinese populations, is advocated as a surrogate marker of VL for guiding PAP. We investigated the utility of qHBsAg to predict high-VL in a multi-ethnic urban cohort with CHB. A consecutive cohort of women with CHB was identified from Barts Health NHS Trust databases in the United Kingdom. We included women with paired HBV DNA and qHBsAg during pregnancy. Women already on antiviral at conception were excluded. A total of 769 pregnancies in 678 CHB pregnant mothers (median age 31 years-old, 8.6% HBeAg+) were included. At median gestational age of 15.3 weeks, HBV DNA was 336 (IQR 44-2998) IU/mL, with 65 (8.5%) being high-VL. Serum qHBsAg was most useful in Black/Black-British/Caribbean/African (AUROC 0.946) with 100% sensitivity and 80.6% specificity to predict high-VL; but it performed less well for other ethnicities: Asian (AUROC 0.877), White (AUROC 0.797) and mixed ethnicities (AUROC 0.742). In conclusion, for settings where healthcare resources are not limited, HBV DNA remains the optimal marker to identify highly viraemic pregnancies for guiding PAP. For resource-limited settings where the prevailing cost is treatment, serum qHBsAg can be used in Black/Black British/Caribbean/African sub-cohorts, but not for other ethnicities.

Ethnic differences in hepatocellular carcinoma prevalence and therapeutic outcomes

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death worldwide. The incidence of HCC is affected by genetic and non-genetic factors. Genetically, mutations in the genes, tumor protein P53 (TP53), catenin beta 1 (CTNNB1), AT-rich interaction domain 1A (ARIC1A), cyclin dependent kinase inhibitor 2A (CDKN2A), mannose 6-phosphate (M6P), smooth muscle action against decapentaplegic (SMAD2), retinoblastoma gene (RB1), cyclin D, antigen presenting cells (APC), AXIN1, and E-cadherin, have been shown to contribute to the occurrence of HCC. Non-genetic factors, including alcohol consumption, exposure to aflatoxin, age, gender, presence of hepatitis B (HBV), hepatitis C (HCV), and non-alcoholic fatty liver disease (NAFLD), increase the risk of HCC.

RECENT FINDINGS

The severity of the disease and its occurrence vary based on geographical location. Furthermore, men and minorities have been shown to be disproportionately affected by HCC, compared with women and non-minorities. Ethnicity has been reported to significantly affect tumorigenesis and clinical outcomes in patients diagnosed with HCC. Generally, differences in gene expression and/or the presence of comorbid medical diseases affect or influence the progression of HCC. Non-Caucasian HCC patients are significantly more likely to have poorer survival outcomes, compared to their Caucasian counterparts. Finally, there are a number of factors that contribute to the success rate of treatments for HCC.

CONCLUSION

Assessment and treatment of HCC must be consistent using evidence-based guidelines and standardized outcomes, as well as international clinical practice guidelines for global consensus. Standardizing the assessment approach and method will enable comparison and improvement of liver cancer research through collaboration between researchers, healthcare providers, and advocacy groups. In this review, we will focus on discussing epidemiological factors that result in deviations and changes in treatment approaches for HCC.

EASL Clinical Practice Guidelines on the management of liver diseases in pregnancy

Liver diseases in pregnancy comprise both gestational liver disorders and acute and chronic hepatic disorders occurring coincidentally in pregnancy. Whether related to pregnancy or pre-existing, liver diseases in pregnancy are associated with a significant risk of maternal and fetal morbidity and mortality. Thus, the European Association for the Study of Liver Disease invited a panel of experts to develop clinical practice guidelines aimed at providing recommendations, based on the best available evidence, for the management of liver disease in pregnancy for hepatologists, gastroenterologists, obstetric physicians, general physicians, obstetricians, specialists in training and other healthcare professionals who provide care for this patient population.

Recent Updates on Viral Oncogenesis: Available Preventive and Therapeutic Entities

Human viral oncogenesis is a complex phenomenon and a major contributor to the global cancer burden. Several recent findings revealed cellular and molecular pathways that promote the development and initiation of malignancy when viruses cause an infection. Even, antiviral treatment has become an approach to eliminate the viral infections and prevent the activation of oncogenesis. Therefore, for a better understanding, the molecular pathogenesis of various oncogenic viruses like, hepatitis virus, human immunodeficiency viral (HIV), human papillomavirus (HPV), herpes simplex virus (HSV), and Epstein-Barr virus (EBV), could be explored, especially, to expand many potent antivirals that may escalate the apoptosis of infected malignant cells while sparing normal and healthy ones. Moreover, contemporary therapies, such as engineered antibodies antiviral agents targeting signaling pathways and cell biomarkers, could inhibit viral oncogenesis. This review elaborates the recent advancements in both natural and synthetic antivirals to control viral oncogenesis. The study also highlights the challenges and future perspectives of using antivirals in viral oncogenesis.

Vertical Transmission of Hepatitis B Virus-An Update

Hepatitis B virus (HBV) infection is a major public health problem in the world. Approximately 296 million people are chronically infected. In endemic areas, vertical transmission is a common route of transmission. There are several strategies for the prevention of HBV vertical transmission, such as antiviral treatment during the third trimester of pregnancy and immunoprophylaxis to newborns that includes the administration of hepatitis B immune globulin (HBIG) and an HBV vaccine. Despite this, immunoprophylaxis failure can occur in up to 30% of infants born to HBeAg-positive mothers and/or with high viral load. Therefore, management and prevention of HBV vertical transmission is of paramount significance. In this article, we provided a review of the epidemiology, mechanisms of pathogenesis and risk factors of vertical transmission, as well as the strategies implemented to prevent the infection.

Characterization of Hepatitis B Virus in Tenofovir-Treated and Untreated Chronically Infected Mothers and Their Immunoprophylaxis Failure Infants

BACKGROUND

Maternal tenofovir disoproxil fumarate (TDF) therapy during late pregnancy can reduce mother-to-infant transmission of hepatitis B virus (HBV). We investigated HBV mutations associated with maternal TDF therapy and their role in infant immunonophylaxis failure (IPF).

METHODS

Serum samples from untreated (n = 89) and TDF-treated (n = 68), highly viremic, chronically infected mothers and their infants were analyzed for HBV DNA by nested polymerase chain reaction (PCR) and direct sequencing.

RESULTS

At delivery, compared with untreated mothers, TDF-treated mothers had a lower HBV DNA titer and a higher frequency of basal core promoter (BCP) gene mutations, but they had similar frequencies in pre-S/S and pre-core/core mutations. The 14 mothers harboring surface "a" determinant mutants did not transmit the mutants to their immunized infants. Such mutants were found in 3 of 13 IPF infants; the 13 mothers had wild-type hepatitis B surface antigen (HBsAg). In univariable analysis, maternal HBV DNA titer (odds ratio [OR]: 1.54; 95% confidence intervals [CI]: 1.02-2.33; P = .039), genotype C (OR: 4.18; 95% CI: 1.28-13.62; P = .018) and pre-S1 wild-type sequence (OR: 6.33; 95% CI: 1.85-21.68; P = .003) at delivery were associated with infant IPF. Multivariable analyses showed that maternal genotype C (OR: 3.71; 95% CI: 1.11-12.36; P = .033) and pre-S1 wild-type (OR: 6.34; 95% CI: 1.79-22.44; P = .004) were associated with infant IPF independently of maternal viremia.

CONCLUSIONS

Along with high maternal HBV DNA titer at delivery, maternal genotype C and pre-S1 wild-type sequence were potential risk factors for infant IPF, although BCP mutations were not. The offspring of pregnant women harboring "a" determinant mutants as major strains seemed to be protected by immunoprophylaxis.

CLINICAL TRIALS REGISTRATION

NCT01312012.

Comparison of tenofovir disoproxil fumarate and telbivudine in preventing hepatitis B transmission in mothers with high viral load

OBJECTIVE

To add to the limited data that exist on the selection of drugs to prevent mother-to-child transmission (MTCT) of hepatitis B virus (HBV).

METHODS

This is a prospective cohort study that enrolled mothers with HBV-DNA ≥2 × 10⁵  IU/ml. All enrolled mothers received either tenofovir disoproxil fumarate (TDF) or telbivudine (LdT) to prevent HBV transmission.

RESULTS

A total of 270 mothers received TDF treatment and 275 mothers received LdT treatment. The predelivery decline in HBV-DNA in the TDF group was higher than the LdT group (3.92 ± 0.93 log IU/ml vs. 3.76 ± 0.94 log IU/ml, P = 0.043). In the primary analysis, the MTCT rate of the TDF group was comparable to that of the LdT group, both in the intention-to-treat analysis (1.5% [4/275] vs. 1.8% [5/273], P > 0.99) and the per-protocol analysis (0% in both groups, P > 0.99). The alanine aminotransferase elevation rates in the TDF group were lower than in the LdT group (17.3% vs. 27.4%, P = 0.005). Less anorexia and more arthralgia were observed in the LdT group than the TDF group.

CONCLUSIONS

TDF and LdT are both effective in preventing MTCT of HBV, but they may cause different adverse events. TDF is more effective in reducing HBV viral load and had fewer alanine aminotransferase abnormalities than LdT.

Infant immune response to hepatitis B vaccine after fetal exposure to telbivudine

Whether telbivudine (LdT) treatment to pregnant women with hepatitis B surface antigen (HBsAg) affects infant immune response to hepatitis B vaccine (HepB) has not been investigated. A total of 127 HBsAg positive mothers and their neonates were enrolled and followed up at 11–13 months. Mothers took LdT (LdT group) or did not receive antiviral therapy (control group). Infant anti-HBs, immune cells and cytokines were measured after HepB was administered according to 0-1-6 procedure. We performed a 1:3 propensity score matching (PSM). Immune indexes in the two groups were compared. Baseline characteristics of mother-baby pairs were comparable in LdT group and control group. Infant anti-HBs geometric mean concentration (GMC) did not differ significantly between the two groups [767.70 (745.35) vs. 711.90 (819.60), P = .599]. There was no difference between the two groups in infant positive rate of anti-HBs [97.8% (91/93) vs. 97.1% (33/34), P = .999] and strong positive rate of anti-HBs [40.9% (38/93) vs. 44.1% (15/34), P = .742]. Infants with negative, low, medium, and high anti-HBs levels were similarly distributed between the two groups (P = .511). No differences in proportion of helper T cells, cytotoxic T cells, B cells, myeloid dendritic cells, and plasmacytoid dendritic cells of infants (P > .05) were detected between the two groups. Children in the LdT and control group had comparable levels of interleukin-2, interleukin-4, interleukin-6, interleukin-10, interleukin-12, interferon-α, interferon-γ and tumor necrosis factor-α (P > .05). Intrauterine exposure to LdT was safe to infant immune response to HepB after birth.

PgRNA kinetics predict HBsAg reduction in pregnant chronic hepatitis B carriers after treatment cessation

Background

Pregenomic RNA (pgRNA) and hepatitis B core-related antigen (HBcrAg) play significant roles in predicting discontinuing treatment outcomes. However, their role in pregnancy has rarely been reported. We aimed to evaluate the performance of pgRNA and HBcrAg kinetics in predicting HBeAg seroconversion and HBsAg reduction postpartum in HBeAg-positive pregnant women.

Methods

Pregnant HBeAg-positive patients receiving antiviral prophylaxis and ceasing treatment postpartum were included. PgRNA and HBcrAg levels were measured before treatment, at 32 weeks of gestation, and at treatment withdrawal postpartum. Other virological and biochemical parameters were regularly examined until 96 weeks postpartum.

Results

Of 76 pregnant chronic hepatitis B (CHB) carriers with a median treatment duration of 18.1 weeks, HBeAg seroconversion and HBsAg reduction >0.3 log₁₀ IU/mL at 96 weeks postpartum occurred in 8 (10.5%) and 13 (17.1%) patients, respectively. HBsAg correlated most strongly with pgRNA, while HBeAg correlated most strongly with HBcrAg. Multivariable regression analysis revealed that postpartum pgRNA decline and peak ALT levels were independent predictors of HBsAg reduction. The area under the curve of the regression model was 0.79 and reached as high as 0.76 through bootstrapping validation. The calibration plot showed that the nomogram had a performance similar to that of the ideal model. A decision tree was established to facilitate application of the nomogram. In addition, HBcrAg kinetics, as an independent predictor, performed poorly in predicting HBeAg seroconversion.

Conclusions

Postpartum pgRNA decline together with peak ALT levels may identify patients with a higher probability of HBsAg reduction after treatment cessation postpartum among pregnant CHB carriers receiving antiviral prophylaxis.

Tenofovir alafenamide in blocking mother-to-child transmission of hepatitis B virus: a multi-center, prospective study

BACKGROUND

Data of tenofovir alafenamide (TAF) in preventing mother-to-child transmission (MTCT) of hepatitis B virus (HBV) are limited. This study aimed to evaluate the effectiveness and safety of TAF for preventing MTCT.

METHODS

Pregnant women with chronic HBV infection, positive for HBeAg and high-level HBV DNA, received oral TAF from gestational weeks 24-28 until postpartum week 4. All infants received HBV immunoprophylaxis. All mothers and infants were followed up until postpartum seven month. The primary outcome was the rate of MTCT at seven month.

RESULTS

Eighty-nine mothers delivered and 91 infants were born. All were followed up to postpartum seven month. TAF was initiated at a mean gestational age of 25.0 (±1.0) weeks with the mean treatment duration of 14.3 (±1.2) weeks before delivery; 92.1% (82/89) mothers discontinued TAF, the median [IQR] time was 5.9 [4.7] weeks postpartum. The HBsAg positive rate was 0% at seven months in 91 infants, no growth retardation and congenital defects. All mothers were tolerated during TAF treatment. At delivery, 82.02% (73/89) mothers achieved HBV DNA < 200,000 IU/ml, 21.35% (19/89) achieved HBV DNA < 500 IU/ml. No significant changes on the mean (±SD) serum phosphate between baseline (1.20 ± 0.10 mmol/L) and at delivery (1.21 ± 0.13 mmol/L, p > .05). Serum creatinine at delivery (52.23 ± 8.50 µmol/L) was higher than baseline (45.97 ± 5.60 µmol/L, p < .05), but within normal range. Nine of 82 mothers stopped TAF treatment after delivery had mild ALT elevation.

CONCLUSION

TAF therapy initiated during the second trimester was effective in preventing MTCT with no safety concerns for mothers and infants (ClinicalTrials.gov number, NCT04065230).

Clinical characteristics of hepatitis flares during pregnancy and postpartum in Chinese chronic hepatitis B virus carriers—a prospective cohort study of 417 cases

Background

In China, it is common for pregnant women with a high load of hepatitis B virus (HBV) to take nucleos(t)ide analogue (NA) to prevent maternal-to-child transmission of HBV. However, the impact of NA intervention on virological and biochemical parameters in pregnant and postpartum women and the safety of drug cessation remain unclear. A prospective observational cohort was established in this study to analyze the clinical characteristics of hepatitis flares in pregnant and postpartum chronic HBV carriers, with or without NA intervention.

Methods

Pregnant women who were chronic HBV carriers were enrolled in this study and divided into an NA intervention group and a non-intervention group according to their preferences. Liver function, HBV DNA level, and HBV serological markers were regularly measured during pregnancy and at approximately 6 weeks, 12 weeks, 24 weeks, 36 weeks, and 48 weeks postpartum.

Results

A total of 417 patients were enrolled, including 303 in the NA intervention group and 114 in the non-intervention group. The incidence rates of postpartum hepatitis flares in both groups were higher than that of during pregnancy (45.7% vs 10.9%, p < 0.001; 41.2% vs 17.7%, p < 0.001). The second trimester was the peak of the incidence of flares during pregnancy and the incidence peak of postpartum flares was about 6 weeks postpartum. A total of 98% (145/148) of postpartum flares occurred within 24 weeks postpartum. After drug cessation, the incidence rate of flares was 34.1% (44/129).

Conclusion

In pregnant chronic HBV carriers, a certain proportion of hepatitis flares occurred during pregnancy and postpartum regardless of whether NA intervention was used, and the incidence of postpartum flares (44.6%) was significantly higher than that (12.8%) of during pregnancy. The flare incidence peaked at approximately 6 weeks postpartum, which may be the time period suitable for treatment. Since 98% of postpartum flares occurred within 24 weeks postpartum, the follow-up after drug cessation should be at least 24 weeks postpartum.

Impact of in vitro fertilization-embryo transfer on mother-to-infant transmission in women with chronic HBV infection

BACKGROUND AND AIMS

In vitro fertilization-embryo transfer (IVF-ET) may increase the risk of mother-to-child transmission (MTCT) of hepatitis B virus (HBV). The purpose of this study was to investigate the impact and safety of IVF-ET on MTCT in women with chronic HBV infection (CHB).

METHODS

The data of 298 women who got pregnant by IVF-ET and their 375 children were collected retrospectively. Mothers were divided into the CHB group (n = 224) and the control group (HBsAg negative, n = 74). After birth, newborns were routinely vaccinated with the hepatitis B vaccine, and infants in the CHB group were injected with hepatitis B immunoglobulin within 2 h after birth. Demographic information, clinical data and laboratory test results were collected. The primary outcome measures were the MTCT rate of HBV, and the secondary outcome measures were the safety of the mother and infant.

RESULTS

There was no case of HBV MTCT in all 282 newborns born in the CHB group and 93 neonates born in the control group. Of the two groups, the birth weight (3056.74 ± 601.65 vs. 2926.24 ± 704.86, P = .083), length (49.22 ± 1.97 vs. 48.74 ± 3.09, P = .167), 5-min Apgar score (9.97 ± 0.21 vs. 9.90 ± 0.51, P = .212), days of pregnancy (265.70 ± 12.73 vs. 262.02 ± 17.50, P = .064) and neonatal malformation rate (0.71% vs. 0, P = 1.000) were similar. Two cases of neonatal malformation occurred in the CHB group. The incidences of pregnancy and childbirth complications were similar between the two groups.

CONCLUSION

IVF-ET does not increase the risk of MTCT in women with chronic HBV infection, and it is safe for mothers and infants.

Tenofovir disoproxil fumarate therapy to prevent hepatitis B virus vertical transmission-A review of maternal and infant outcomes

Hepatitis B virus (HBV) is a global health problem. Vertical transmission of HBV from HBV surface antigen (HBsAg)-positive mothers to their infants is the most common cause of HBV infection worldwide. The use of passive-active immunoprophylaxis is >90% effective in reducing the risk of vertical transmission, but immunoprophylaxis failure can occur in infants born to mothers with high viraemia. Thus, it is recommended that pregnant women with HBV-DNA level >200 000 IU/ml receive nucleos(t)ide analogue (NA) treatment [i.e. tenofovir disoproxil fumarate (TDF), lamivudine or telbivudine] during third trimester to prevent infant immunoprophylaxis failure. TDF is recommended as the first-line therapy based on available data on efficacy, safety and resistance profile. However, maternal immunological reconstitution following parturition can increase immune-mediated flares to viral antigens that is potentially exacerbated following TDF withdrawal. In this article, we review available data on the efficacy and safety of TDF administration to prevent HBV mother-to-child transmission. We also discuss changes in maternal viral markers [i.e. HBV-DNA, HBV e antigen and HBsAg] and alanine aminotransferase during follow-up post-partum in mothers received NA to prevent HBV vertical transmission.

Efficacy and safety of tenofovir disoproxil fumarate or telbivudine used throughout pregnancy for the prevention of mother-to-child transmission of hepatitis B virus: A cohort study

OBJECTIVE

Tenofovir disoproxil fumarate (TDF) use compared with telbivudine (LdT) use throughout pregnancy has not been adequately investigated. To compare the efficacy and safety of TDF and LdT for the prevention of mother-to-child transmission (MTCT) of hepatitis B from highly viremic mothers throughout pregnancy in real-world settings.

STUDY DESIGN

This was a single-center, retrospective cohort study. From January 1, 2013, to December 31, 2018, we retrospectively enrolled 602 mothers with chronic hepatitis B (CHB) who received antiviral treatment throughout pregnancy at Beijing Ditan Hospital. A total of 562 mothers met the inclusion criteria, with 167 in the TDF group and 395 in the LdT group. Mothers and infants were followed for 28 weeks postpartum. The primary endpoint was the MTCT rate of HBV. The secondary endpoints were the safety profiles in mothers and infants.

RESULTS

The MTCT rates were 0 % in both the TDF and LdT groups. The rates of neonatal congenital abnormalities were similar between the TDF and LdT groups (1.2 % vs 1.8 %, P = 0.896). There were no significant differences in perinatal complications between the two groups (all P > 0.05). There were also no significant differences in gestational age or infant height, weight, Apgar score. The level of HBV DNA at 28 weeks postpartum was an independent risk factor for postpartum alanine aminotransferase (ALT) flares (OR = 2.348, 95 % CI: 1.100-5.016, P = 0.027).

CONCLUSION

TDF and LdT treatments throughout pregnancy in mothers with CHB were equally effective in preventing MTCT and safe.

Absence of chronicity in infants born to immunized mothers with occult HBV infection in Taiwan

BACKGROUND & AIMS

In the Taiwanese population born in the universal vaccination era, HBsAg carrier rates have fallen below 2%, while approximately 5% develop occult hepatitis B infection (OBI). However, the potential for transmission from mothers with OBI to their infants has not been well studied. We aimed to investigate whether mothers with OBI could transmit HBV to their babies.

METHODS

A total of 253 pregnant women who were born after July 1986 and had been fully vaccinated against HBV during infancy were recruited from a tertiary hospital in Northern Taiwan. HBV serology and DNA levels were determined. Babies born to mothers with OBI were followed-up until 1 year of age. The surface genes were sequenced.

RESULTS

HBV infection was documented in 18 vaccinated mothers, 2 of whom were HBsAg-reactive (0.79 %). Seventeen were positive for HBV DNA, among whom 16 (6.32%) presented with OBI with a median DNA level of 145 IU/ml (interquartile range: 37.8-657.3 IU/ml). Eleven babies born to 10 mothers with OBI were recruited. Three babies were HBsAg-reactive, and 2 were positive for HBV DNA (17.0 and 212.0 IU/ml). Seven mothers with OBI carried multiple surface gene variants. Two transiently infected babies harbored variants originating from their mother's HBV quasi-species. All infants received complete hepatitis B vaccines. At 12 months of age, none of the babies were positive for HBsAg or HBV DNA.

CONCLUSIONS

It was possible for mothers with OBI to transmit HBV to their babies, who consequently harbored surface gene variants originating from their mothers' minor variants. Viremia was cleared 1 year after completing the hepatitis B vaccination series.

LAY SUMMARY

Since initiating the hepatitis B vaccination program in Taiwan, the rate of young individuals (i.e. born after 1986) carrying the HBV surface antigen has fallen below 2%, although around 5% of vaccinated individuals develop occult HBV infections. Herein, we show that pregnant mothers with occult HBV infections can transmit HBV to their offspring. However, no infant had sustained infection at 1 year of age having completed a full HBV vaccination series.

Antiviral Therapy for a Postpartum Flare in Women with Chronic HBV Infection Shortens the ALT Recovery Time and Reduces Hepatitis Re-Flare Rates within 4 years

Background

Few studies explored whether anti-hepatitis B virus (HBV) therapy should be initiated during postpartum hepatitis flare.

Aim

This study aimed to analyze the effect of anti-HBV therapy on postpartum hepatitis flare and evaluate the prognosis within 4 years postpartum.

Methods

This retrospective study enrolled hepatitis B surface antigen (HBsAg)-positive and hepatitis B e antigen (HBeAg)-positive pregnant women with HBV DNA ≥ 106 IU/mL. A total of 152 pregnant women were included: 103 in the prophylactic anti-HBV therapy group (PT-G) and 49 in the non-prophylactic anti-HBV therapy group (NPT-G). The women with a postpartum flare were assigned to the anti-HBV therapy group (AT-G) and non-anti-HBV therapy group (NAT-G) to analyze the effect of postpartum anti-HBV therapy on hepatitis flare. Virological and biochemical parameters were assessed.

Results

Taking postpartum 12 weeks as the cutoff point, the ALT recovered time for postpartum flare women is shorter in AT-G (n = 16, 42.1%) or PT-G (n = 23, 34.8%) than in NAT-G (n = 14, 23.0%; x 2 = 4.067, P=0.044) or NPT-G (n = 4, 11.1%; x 2 = 5.579, P=0.018). Taking postpartum 26 weeks as the cutoff point, the ALT recovered time is shorter in AT-G (n = 35, 57.3%) or PT-G (n = 44, 66.7%) than in NAT-G (n = 32, 84.2%; x 2 = 7.707, P=0.006) or NPT-G (n = 16, 44.4%; x 2 = 4.749, P=0.029). Postpartum flare recovery time was positively correlated with HBV DNA level at delivery [r = 0.223, P=0.025, 95%CI (0.022～0.41)]. The hepatitis re-flare rates within postpartum 4 years in AT-G (n = 3, 9.68%) is lower than that in NAT-G (n = 24, 45.4%; x 2 = 14.003, P ≤ 0.001). The HBeAg, HBsAg, HBV DNA, and ALT level at postpartum 4 years in AT-G were lower than that in NAT-G (P < 0.001).

Conclusion

Anti-HBV therapy for postpartum hepatitis flare of women with chronic HBV could shorten the ALT recovery time and reduce hepatitis re-flare rates within 4 years of postpartum.

The role of tenofovir disoproxil fumarate for preventing vertical transmission of hepatitis B

Background

Since immunoprophylaxis failure can occur if maternal serum hepatitis B virus (HBV) DNA levels are >200,000 IU/ml, tenofovir disoproxil fumarate (TDF) therapy has been investigated for preventing mother to child transmission (PMTCT).

Methods

A literature search for maternal TDF therapy for PMTCT between 1/1/2015 and 7/1/21 on PUBMED, EMBASE, Cochrane, CNKI, and Wanfang databases was performed. Data from RCTs in English or Chinese were extracted and reviewed. The outcomes of interest included the efficacy and safety of TDF versus placebo for PMTCT.

Results

Among 11 RCTs identified from the databases, the risk-of-bias was low. All studies demonstrated that maternal TDF therapy initiated from the second or third trimester for highly viremic chronic hepatitis B mothers is highly effective and safe in the PMTCT of HBV, except one RCT performed in Thailand which showed no therapeutic advantage on TDF treatment versus placebo for PMTCT (0% vs 3% transmission). Recent emerging data suggest that maternal TDF therapy initiated at the 2nd or early 3rd trimester in mothers with HBV DNA >200,000 IU/ml achieved viremic control before delivery. In the 4-year long follow-up study for maternal TDF therapy, there were no impacts on infants’ physical growth, psychological or mental development, and bone mineral density after fetal exposure to TDF. In the light of updated efficacy and safety data from RCTs, an algorithm was proposed. The approaches in resource-limit areas were discussed.

Conclusions

TDF is safe for both mothers and infants as the preferred therapy for PMTCT in highly viremic mothers. TDF should be initiated at the second or early third trimester in the combination of the appropriate infants’ immunoprophylaxis.

Hepatitis B virus genotype is an independent prognostic factor of telbivudine and tenofovir treatment in hepatitis B surface antigen-positive pregnant women

To investigate whether HBV genotype influences the effect of tenofovir and telbivudine on HBV DNA and RNA levels in HBsAg-positive pregnant women. This was a retrospective study of 74 HBsAg-positive pregnant women in Guizhou of China. All patients were treated with telbivudine or tenofovir from 12 weeks of pregnancy and HBV infection to the date of delivery. Blood samples were collected at 12-24, 28-32, and 36-40 weeks of pregnancy for the measurement of genotype, HBsAg, hepatitis B e antigen (HBeAg), HBV DNA, HBV RNA, and liver function, including alanine transaminase, aspartate transaminase, total bilirubin, total bile acids, cholinesterase, alkaline phosphatase (ALP), and gamma-glutamyl transferase. All women with HBsAg were followed up. The HBV genotype was B in 64.9% and C in 35.1%. There were 37 patients of telbivudine and tenofovir group respectively. The telbivudine and tenofovir groups showed no differences in demographic and clinical characteristics, including liver function tests, HBsAg, HBeAg, log10(HBV DNA), and log10(HBV RNA). Compared with baseline (12-24 weeks), telbivudine group showed a significant increase in ALP and significant reductions in HBsAg, HBeAg, log10(HBV DNA), and log10(HBV RNA) at 36-40 weeks (p < .05). Tenofovir group exhibited a significant increase in ALP and significant reductions in HBeAg, log10(HBV DNA), and log10(HBV RNA) at 36-40 weeks, compared with baseline (p < .05). HBV genotype (B vs. C) was independently associated with HBV DNA change after therapy (p = .005). In telbivudine group, log10 (HBV DNA) increased from 3.38 (2.00-7.30) to 7.43 (4.68-8.70). In tenofovir group, log10 (HBV DNA) decreased from 7.52 (3.32-8.70) to 2.98 (2.00-5.01). HBV genotype was independently associated with HBV DNA change response to telbivudine or tenofovir in pregnant women with hepatitis B. These findings might be helpful for risk assessment regarding vertical transmission of HBV in HBeAg-positive mothers treated with nucleos(t)ide analogues.

Outcomes of Hepatitis B Immunoglobulin and Hepatitis B Vaccination in High-Risk Newborns Born to HBeAg-positive Mothers

BACKGROUND

To evaluate the protective efficacy of a hepatitis B (HB) vaccination program in Taiwan among high-risk children.

MATERIAL AND METHODS

Children born to HBeAg-positive mothers from 2001 to 2010 were invited back. Blood samples for hepatitis B virus (HBV) seromarkers were taken and the children underwent hepatobiliary ultrasonography. Perinatal factors including delivery mode and vaccination history were collected from their medical records. According to the results of HBV serological markers, the children were initially classified into five groups: HBV naïve, HB vaccine responder, HBsAg carrier, recovered from HBV infection, and anti-HBc-positive alone. Children in the HBV naïve and anti-HBc-positive alone groups who presented with an anamnestic response after a booster HB vaccine were re-assigned to the vaccine responder and recovered from infection groups, respectively.

RESULTS

All of the 196 enrolled children received postnatal hepatitis B immunoglobulin (HBIG) and HB vaccinations, of whom one was HBV naïve (0.5%), 109 were vaccine responders (55.6%), 21 were carriers (10.7%), and 65 recovered from infection (33.2%). Among the 21 carriers, 14 (66.7%) presented in the immunotolerant phase. Cesarean section was the only significant perinatal factor between the carriers (5.3%) and those who recovered from infection (37.7%) (p=0.007).

CONCLUSIONS

In this study, there was a 43.9% HBV infection rate and 10.7% HBsAg carrier rate in high-risk Taiwanese children even after receiving HBIG and HB vaccinations. Cesarean section may protect newborns from becoming HBsAg carriers, while HBV genotype and time of HBIG injection did not contribute to the HBV carrier rate.

Comparison of the efficacy and safety of tenofovir and telbivudine in interrupting mother-to-child transmission of hepatitis B virus

The present study is aimed to evaluate and compare the efficacy and safety of tenofovir (TDF) and telbivudine (TBV) in interrupting hepatitis B virus (HBV) mother-to-child transmission (MTCT), and to provide evidence-based treatment options to clinicians and patients.Hepatitis B e-antigen (HBeAg)-positive pregnant women (644 in total) with high HBV DNA load (≥2 × 105 IU/mL) and who received TDF (n = 214) or TBV (n = 380) in the second or third trimester, or received no treatment (n = 50) were included in this retrospective analysis.HBV DNA levels in mothers at delivery were significantly lower than baseline in the 2 treatment groups. HBV DNA levels in the TDF group were significantly different between the mothers receiving treatment in the second trimester and those receiving treatment in the third trimester; however, significant difference was not observed in the TBV group. The proportion of hepatitis B surface antigen (HBsAg)-positive infants at the age of 7 to 12 months in the TDF, TBV, and control groups were 0.00% (0/174), 0.30% (1/331), and 5.0% (2/40) with a significant difference between the treatment groups and the control group, but no difference between the TDF and TBV group (P > .05). However, no serious adverse events were observed in infants and mothers of all groups.TBV and TDF can effectively reduce the HBV DNA level and MTCT rate in pregnant women with high HBV DNA load (≥2 × 105 IU/mL); both antiviral drugs are safe for infants and mothers. Since TDF was more effective in reducing HBV DNA levels during the second trimester, its use during the period is recommended to prevent HBV MTCT.

Vertical transmission of hepatitis B virus: propositions and future directions

ABSTRACT

Chronic hepatitis B virus (HBV) infection due to vertical transmission remains a critical concern with regards to eliminating HBV infection. Implementation of hepatitis B vaccine, the foundation to prevent perinatal and horizontal transmission, has reduced the prevalence of HBV by >80%. In countries where the hepatitis B immune globulin (HBIG) is available, such as China and the United States, the administration of HBIG and hepatitis B vaccine to the infants of mothers who are positive for hepatitis B surface antigen has become a standard practice and is effective in preventing vertical transmission. Accumulating evidence on the efficacy and safety of antiviral prophylaxis during pregnancy indicates the probability of attaining the goal of the World Health Organization to eliminate hepatitis by 2030. In this review, we discuss the transmission routes, diagnostic criteria, and preventive strategies for vertical transmission. A preventive program that includes screening before pregnancy, antiviral prophylaxis during pregnancy, and postpartum immunoprophylaxis provides "perfect strategies" to eliminate vertical transmission. However, there is still a notable gap between "perfect strategies" and real-world application, including insufficient coverage of timely birth dose vaccine and the efficacy and necessity of HBIG, especially in mothers who are negative for hepatitis B envelope antigen. In particular, there is a clear need for a comprehensive long-term safety profile of antiviral prophylaxis. Therefore, feasible and cost-effective preventive strategies need to be determined across regions. Access also needs to be scaled up to meet the demands for prophylaxis and prevalence targets.

Distribution Evaluation of Tenofovir in the Breast Milk of Mothers With HBeAg-Positive Chronic HBV Infection After Treatment With Tenofovir Alafenamide and Tenofovir Disoproxil Fumarate by a Sensitive UPLC-MS/MS Method

Tenofovir alafenamide (TAF) is a novel prodrug of tenofovir (TFV) that has been approved for the treatment of chronic hepatitis B virus (HBV) infection. It has greater plasma stability and more favorable renal safety than tenofovir disoproxil fumarate (TDF), the first approved oral prodrug of TFV. However, the distribution of TFV in the breast milk of mothers treated with TAF is still unclear. In this study, sixteen participants with chronic HBV infection were enrolled and received antiretroviral therapy with 25 mg of TAF or 300 mg of TDF daily from 24 to 28 weeks of gestation until the 4th week postpartum. For the first time, the distribution of TFV in the breast milk of mothers with chronic HBV infection treated with TAF and its difference from TDF were evaluated by using a sensitive UPLC-MS/MS method. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C18 column (1.7 µm 2.1 × 100 mm). Mass spectrometry analysis was performed in positive electrospray ionization mode and multiple reaction monitoring (MRM) conditions of transitions m/z 288.1→176.2 for TFV. This method was linear from 0.5 to 500 ng/ml. Surprisingly, on the third postpartum day, the median Cmax of TFV in the breast milk was much higher in the mothers treated with TAF (101.2 ng/ml) than TDF (21.6 ng/ml) at a similar Tmax of 4 h. Accordingly, the median AUC0-8 value was 755.6 ng h/mL in the mothers taking TAF, which was at a 5-fold higher level than TDF. The concentration of TFV in the breast milk of mothers in both groups decreased with increasing lactation time. These data indicated that there was a relatively higher exposure of TFV in the breast milk of mothers taking TAF, despite the lower dosage compared to TDF. This study provides support for further evaluating the safety of breastfeeding after the administration of TAF and TDF.

Chronic hepatitis B in pregnant women: Current trends and approaches

Chronic hepatitis B (CHB) is a significant public health problem worldwide. The aim of the present review is to summarize the actual trends in the management of CHB in pregnant women. The prevalence of hepatitis B virus (HBV) infection in pregnant women is usually comparable to that in the general population in the corresponding geographic area. All women have to be screened for hepatitis B surface antigen (HBsAg) during pregnancy. Additional examinations of pregnant women with CHB may include maternal hepatitis B e antigen, HBV viral load, alanine aminotransferase level, and HBsAg level. The management of pregnancy depends on the phase of the HBV infection, which has to be determined before pregnancy. In women of childbearing age with CHB, antiviral therapy can pursue two main goals: Treatment of active CHB, and vertical transmission prevention. During pregnancy, tenofovir is the drug of choice in both cases. A combination of hepatitis B immunoglobulin and vaccine against hepatitis B should be administered within the first 12 h to all infants born to mothers with CHB. In such cases, there are no contraindications to breastfeeding.

Developmental consequences of children born from mothers with telbivudine treatment during late pregnancy: A prospective study with 3-year follow-up

We prospectively investigated the neurological development in infants born from mothers treated with telbivudine (LdT) in the third trimester for prevention of hepatitis B virus (HBV) mother-to-infant transmission. Mothers with high HBV load were assigned to either the LdT group (n = 81, 600 mg of LdT each day from gestational week 28 to delivery) or the Control group (n = 39, untreated). Their infants were followed for 36 months to assess physical and neurological developments with Gesell Developmental Schedule tools. At 12 months after birth, the mean scores in the LdT group for gross motor, fine motor, adaptive, linguistic, and personal social domains were similar to those in the Control group. At 36 months, infants in the LdT group had higher mean scores for gross motor than the Control group (98.42 ± 9.69 vs. 94.54 ± 7.48, P = 0.03). In the LdT group, the rates of normal development were higher for gross motor (96.30% vs. 82.05% P = 0.01) and lower for adaptive (74.07% vs. 92.31% P = 0.02). Multivariate regression analyses showed that exposure to LdT during pregnancy was independently associated with infant’s development in gross motor (OR 6.49, 95% CI 1.37–30.20, P = 0.02) and adaptive (OR 0.18, 95% CI 0.05–0.71, P = 0.01) at 36 months. These results suggest that prenatal LdT exposure might affect neurological development in long-term observation.

Abbreviations: LdT: telbivudine; HBV: hepatitis B virus; HBsAg: hepatitis B surface antigen; HBeAg: hepatitis Be antigen; HbsAb: hepatitis B surface antibody; ALT: alanine aminotransferase; NA: nucleoside/nucleotide analog; LAM: lamivudine; MTCT: mother-to-child transmission; GDS: Gesell Developmental Schedule; OR: odds ratio; CI: confidence interval; DQ: developmental quotient; RMB: renminbi; BMI: body mass Index; HBIG: hepatitis B immunoglobulin.

Benefits and Risks of Antiviral Treatment during Pregnancy in Patients with Chronic Hepatitis B

Hepatitis B virus (HBV) is a main cause of chronic liver disease worldwide and can lead to severe liver diseases. The World Health Organization has planned to eliminate viral hepatitis, including hepatitis caused by HBV and hepatitis C virus, by 2030. As mother-to-child transmission (MTCT) of HBV is a main cause of chronic HBV infection, MTCT prevention is the main target to reduce the risk of chronic HBV infection and eliminate the disease. Recent clinical trials and meta-analyses found that antiviral therapy could prevent MTCT effectively in mothers with ≥200,000 IU/mL of HBV DNA, in combination with serial vaccination and hepatitis B immune globulin administration in infants. Despite the preventive role of antivirals for MTCT of HBV, there are several concerns regarding antiviral therapy with respect to the safety of the mother and fetus during pregnancy. This review summarizes the benefits and risks of antiviral treatment during pregnancy in women with chronic HBV infection.

Risk factors related to postpartum hepatic inflammation in pregnant women with chronic hepatitis B

OBJECTIVES

To investigate liver function after pregnancy in women with chronic hepatitis B virus (HBV) and factors related to postpartum abnormalities.

METHODS

A total of 317 pregnant women were included in this study and 138 had an HBV DNA level. In this trial, the highest number and proportion of hepatitis B surface antigen-positive mothers with postpartum hepatic inflammation were at 1 month after delivery.

RESULTS

Baseline liver function of postpartum women with hepatic inflammation was significantly higher than that in those before delivery. The rates of hepatitis B e-antigen (HBeAg)-positive status, baseline HBV DNA levels, gestational diabetes mellitus, and antiviral therapy during pregnancy were significantly higher in the hepatic inflammation group than in the control group. Among the 138 women who received antiviral therapy, 83 withdrew from antiviral therapy immediately after delivery and 55 continued antiviral therapy for at least 1 month after delivery. Multivariate logistic regression analysis showed that HBeAg-positivity and gestational diabetes mellitus were associated with hepatic inflammation after delivery. Postpartum hepatic inflammation occurred mostly at 1 month after delivery in pregnant women with HBV infection.

CONCLUSIONS

Close monitoring of women with HBV during pregnancy is required, especially for those who are HBeAg-positive and have gestational diabetes mellitus.

Antiviral kinetics of tenofovir alafenamide and tenofovir disoproxil fumarate over 24 weeks in women of childbearing potential with chronic HBV

Background/Purpose

Use of tenofovir disoproxil fumarate (TDF) improves patient outcomes in preventing mother-to-child transmission (pMTCT) of the hepatitis B virus (HBV) in mothers with chronic HBV and high viral loads. Given the lack of data for tenofovir alafenamide (TAF) in pMTCT, rates of early viral suppression with TAF and TDF were evaluated in women of childbearing potential (WOCBP) participating in 2 randomized, double-blind, Phase 3 studies in chronic HBV.

Methods

In a patient subset meeting WOCBP criteria and with baseline HBV DNA >200,000 IU/mL, rates of viral suppression with TAF or TDF in achieving the target of HBV DNA <200,000 IU/mL at weeks 12 and 24 were assessed. Multivariate logistic regression was used to identify factors predictive of failure to suppress HBV DNA to the target level.

Results

In 275 of 1298 (21%) patients meeting WOCBP criteria with high viral load, 93% and 96% had HBV DNA <200,000 IU/mL at weeks 12 and 24, respectively. Results for TAF (n = 194) vs TDF (n = 81) treatment were similar at weeks 12 and 24 (94% vs. 90% and 97% vs. 93%), respectively. High baseline HBV DNA level, genotype D infection, and prior interferon (week 24 only) were predictive of failure to achieve the target level. Both treatments were well tolerated with TAF showing less impact on renal and bone parameters.

Conclusions

In WOCBP with high VL, no differences were found between TAF and TDF in reducing HBV DNA to levels associated with lower transmission risk. These data support ongoing studies of TAF for pMTCT.

Influence of different delivery modes and HBV DNA titers on mother-to-child transmission of hepatitis B

BACKGROUND

The influence of different delivery modes on the mother-to-child transmission (MTCT) rate of pregnant women with high hepatitis B viremia was investigated.

METHODS

A retrospective analysis was performed on data for 855 hepatitis- B -virus (HBV) carrier mothers who received regular prenatal care and delivered at the First Affiliated Hospital of Jinan University from January 2011 to October 2015. The neonates were classified into three groups according to the delivery mode: eutocia (438 cases), Non-parturient cesarean delivery (371 cases), and parturient cesarean delivery (46 cases). The neonatal HBV surface antigen (HBsAg) positive rates of the three delivery groups were comparatively analyzed to determine the influence of the delivery mode on HBV MTCT. Of the 855 HBV-carrier mothers, 480 mothers and respective newborns were tested for HBV-DNA and classified into four groups: HBV DNA≥10⁷ copies/mL (96 cases), 10⁵≤HBV DNA<10⁷ copies/mL (37 cases), 10³≤HBV DNA<10⁵ copies/mL (85 cases), and HBV DNA<10³ copies/mL (262 cases). The effect of the HBV DNA titers of these pregnant women on HBV MTCT was analyzed.

RESULTS

Statistically significant (P<0.05) differences were found among the HBsAg positive rates of neonates of HBV-carrier pregnant women delivered by the three methods from HBV-carrier pregnant women with HBV DNA≥107 copies/mL. No statistically significant (P>0.05) differences among the HBsAg positive rates were found for neonates delivered by the three methods from HBV-carrier pregnant women with HBV DNA<10⁷ copies/mL.

CONCLUSIONS

The delivery mode may influence the risk of HBV maternal-to-infant vertical transmission for HBV-carrier pregnant women with HBV DNA≥10⁷ copies/mL. That is, elective cesarean section may reduce the HBV maternal-to-infant vertical transmission.

High Prevalence of Preexisting HBV Polymerase Mutations in Pregnant Women Does Not Limit the Antiviral Therapy Efficacy

Background

HBV-resistant mutants in treatment-naïve patients may lead to antiviral treatment failure. It is not clear if HBV mutants are present in pregnant women and about the influence of the preexisting mutants on the short-term antiviral therapy during pregnancy.

Method

We enrolled 73 pregnant women with high HBV DNA load and telbivudine (TBV) treatment during pregnancy in this retrospective study. The UDPS was used to detect the HBV mutations before and after the TBV treatment.

Results

Before TBV treatment, the complexity of HBV quasispecies of all subjects was 0.40 ± 0.09; 41.1% (30/73) and 53.4% (39/73) subjects had rtM204I/V and rtN236 T/A detected, respectively; and 9.6% (7/73) patients had more than 20% frequency mutation of rtM204I/V, which was also similar with high frequency of rtN236 T/A mutation (41.1% vs. 53.4%, P=0.136; frequencies >20%: 9.6% vs. 5.5%, P=0.347). After TBV treatment, 71.2% (52/73) subjects had HBV DNA load ≥ 10³ IU/mL at delivery. Among them, 75.0% of patients with rtM204I positive had HBV DNA load ≥10³ IU/mL at delivery, which was comparable with the subjects without rtM204I (75.0% vs. 70.8%, P=0.710). No changes were found in the frequencies and the complexity of HBV quasispecies of rtM204I mutation after the TVB treatment.

Conclusion

The prevalence of preexisting drug-resistant mutations among pregnant women was high using UPDS. However, the preexisting HBV mutation had limited influence on the efficacy of short-term TBV treatment, and TBV treatment during late pregnancy seemed not to increase the risk of emerging HBV-resistant mutants.

Analysis of long-term safety and efficacy of nucleos(t)ide analogue therapy for chronic hepatitis B throughout pregnancy

BACKGROUND

Limited data exist regarding the efficacy and long-term safety of nucleos(t)ide analogue therapy throughout pregnancy for women with chronic hepatitis B and their children.

METHODS

This retrospective cohort study included 165 women in total: 91 women received telbivudine (LDT) and 74 women received tenofovir (TDF) throughout pregnancy. The virological response and safety in women were recorded, and the physical development and bone mineral density in children were evaluated up to 5 years of age.

RESULTS

The rate of virological breakthrough in women was 4.24% overall (7.70% in LDT group and 0% in TDF group; P < 0.05). No cases of renal injury or other obstetric adverse events occurred in either group of women. Among the children, only one child had a significantly low Z score for weight for age (<-2), and no children had a significantly low Z score for height for age or bone mineral density. No significant difference was found between the children in the two groups.

CONCLUSIONS

Nucleos(t)ide analogue therapy with TDF or LDT throughout pregnancy had no effect on the long-term physical development and bone development of children. In addition, the use of TDF throughout pregnancy had better long-term antiviral efficacy than LDT in women, with no evidence of renal toxicity.

Viral hepatitis and pregnancy

The management of viral hepatitis in the setting of pregnancy requires special consideration. There are five liver-specific viruses (hepatitis A, B, C, D, E), each with unique epidemiology, tendency to chronicity, risk of liver complications and response to antiviral therapies. In the setting of pregnancy, the liver health of the mother, the influence of pregnancy on the clinical course of the viral infection and the effect of the virus or liver disease on the developing infant must be considered. Although all hepatitis viruses can harm the mother and the child, the greatest risk to maternal health and subsequently the fetus is seen with acute hepatitis A virus or hepatitis E virus infection during pregnancy. By contrast, the primary risks for hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis D virus are related to the severity of the underlying liver disease in the mother and the risk of mother-to-child transmission (MTCT) for HBV and HCV. The prevention of MTCT is key to reducing the global burden of chronic viral hepatitis, and prevention strategies must take into consideration local health-care and socioeconomic challenges. This Review presents the epidemiology of acute and chronic viral hepatitis infection in pregnancy, the effect of pregnancy on the course of viral infection and, conversely, the influence of the viral infection on maternal and infant outcomes, including MTCT.

Prevention of Hepatitis B Virus Infection and Liver Cancer

Hepatocellular carcinoma (HCC) is one of the five leading causes of cancer death in human. Hepatitis B virus (HBV) is the most common etiologic agent of HCC in the world. Prevention is the best way to control cancer. There are three levels of liver cancer prevention, i.e., primary prevention by HBV vaccination targeting the general population starting from birth dose, secondary prevention by antiviral agent for high-risk subjects with chronic HBV infection, and tertiary prevention by antiviral agent to prevent recurrence for patients who have been successfully treated for liver cancer. Primary prevention by hepatitis B vaccination is most cost effective, the cancer preventive efficacy support it as the first successful example of cancer preventive vaccine in human. Addition of hepatitis B immunoglobulin immediately after birth and antiviral agent during the third trimester of pregnancy to block mother-to-infant transmission of HBV are existing or possible emerging strategies to enhance the prevention efficacy of HBV infection and its related liver cancer. Secondary prevention with current antiviral agents may reduce the risk or delay the onset of HCC development, but could not eradicate HBV infection and HCC. Better antiviral therapeutic agents are needed for better secondary prevention.

Role of tenofovir disoproxil fumarate in prevention of perinatal transmission of hepatitis B virus from mother to child: a systematic review and meta-analysis

BACKGROUND/AIMS

To prevent the perinatal transmission of hepatitis B virus (HBV) from mother to child, administration of an antiviral agent during pregnancy has been attempted in women who are either hepatitis B e antigen positive or have a high viral load. In this systematic review and meta-analysis with randomized controlled trials, we analyzed the efficacy and safety of tenofovir disoproxil fumarate (TDF) in preventing the perinatal transmission of HBV in pregnant women who have high HBV DNA titers.

METHODS

Multiple comprehensive databases (PubMed, EMBASE, and Cochrane databases) were searched for studies evaluating the efficacy of TDF for the prevention of perinatal transmission of HBV.

RESULTS

Two studies (one open label study and one double blind study) were included and analyzed. Intention-to-treat analysis (527 pregnancies) showed that the preventive effect of TDF was not significant (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.13 to 2.17; p = 0.38, I2 = 81%). However, the per-protocol analysis showed that TDF significantly reduced perinatal transmission (OR, 0.10; 95% CI, 0.01 to 0.77; p = 0.03, I2 = 0%). There was no significant difference between the TDF group and the control group with respect to maternal and fetal safety outcomes.

CONCLUSION

In pregnant women who have high HBV DNA titers, TDF can reduce the perinatal transmission from mother to child without significant adverse events.

2019 Chinese Clinical Practice Guidelines for the Prevention of Mother-to-child Transmission of Hepatitis B Virus

To develop the evidence-based guidelines for managing mother-to-child transmission of hepatitis B virus in China, a multidisciplinary guideline development group was established. Clinical questions were identified from two rounds of surveys on the concerns of first-line clinicians. We conducted a comprehensive search and review of the literature. A grading of recommendations' assessment, development, and evaluation system was adopted to rate the quality of evidence and the strength of recommendations. Recommendations were formulated based on the evidence, overall balance of benefits and harms (at individual and population levels), patient/health worker values and preferences, resources available, cost-effectiveness, and feasibility. Eventually, recommendations related to 13 main clinical concerns were developed, covering diagnostic criteria, treatment indications, antiviral therapy choice, timing to initiate and discontinue treatment, immunoprophylaxis strategy at birth, and how to deal with special situations, such as unintended pregnancy, assisted reproduction, and breastfeeding. The guidelines are intended to serve as guidance for clinicians and patients, to optimize the management of majority of pregnant women who are positive for hepatitis B surface antigen. Guideline registration: International Practice Guide Registration Platform (IPGRP-2018CN040).

The safety and efficacy of tenofovir disoproxil fumarate used throughout pregnancy for mothers with chronic hepatitis B

BACKGROUND

Antiviral therapy throughout pregnancy in women with chronic hepatitis B (CHB) during pregnancy has been suggested; however, the data of tenofovir disoproxil fumarate (TDF) are limited. The aim of this study was to evaluate the safety and efficiency in women with CHB.

METHODS

It was a single-center, retrospectively study. Eighty-one women received TDF 300 mg/day before pregnancy. Sixty-three women did not receive antiviral treatment. All infants in both groups received immunoprophylaxis. Mothers and infants were followed at least postpartum 7 months. The primary endpoint was the safety of mothers and infants. The secondary endpoints were mother-to-child transmission (MTCT) rate and hepatitis B virus (HBV) DNA suppression.

RESULTS

TDF was well tolerated in the mothers. The rates of neonatal congenital abnormalities were similar between the two groups (3.7% or 3/81 versus 3.3% or 2/63, P = 1.000). There were also no significant differences in infant length and weight, Apgar score (1 minute), rate of low birth weight, gestational age, or rate of cesarean section between the two groups. TDF significantly reduced the viral load (3.4 ± 0.5 log IU/mL versus 6.3 ± 1.5 log IU/mL, P < 0.001) and the ALT levels (19.9 ± 10.2 versus 46.8 ± 44.8 U/L, P < 0.001) before delivery. At 7-month postpartum, the MTCT rate was 0% in the TDF-treated group when compared with 6.3% (4/63) in the untreated group (P = 0.035).

CONCLUSION

TDF used throughout pregnancy can safely reduce the rate of MTCT.

The safety of antiviral therapy and drug withdrawal for the prevention of mother-to-child transmission of HBV during pregnancy

The efficacy of prenatal antiviral therapy (AVT) for preventing the vertical transmission of hepatitis B virus (HBV) is well demonstrated. However, data are limited regarding the safety of postpartum cessation of AVT, which may induce alanine aminotransferase (ALT) elevation. We aimed to investigate the necessity of prolonging maternal AVT after delivery. Chronic hepatitis B mothers at the immune-tolerant phase with HBV DNA levels >6 log10  IU/mL were prospectively enrolled and received AVT during the third trimester until delivery. Patients were offered to discontinue AVT either at delivery or postpartum week (PPW) 6. In addition, mothers who deferred AVT during pregnancy served as the control group. All mothers were followed until PPW 52 for clinical and virological parameters of hepatitis flares. Among 118 mothers recruited, 91 received AVT with 53 (group A) and 24 (group B) discontinue their treatment at delivery and PPW 6, respectively. Twenty-seven mothers who deferred AVT during pregnancy were followed as the control (group C). A total of 104 of 118 mothers who completed the study, 50% (52/104) had postpartum-elevated ALT levels, which were mild and moderate except 6 of 104 (5.77%) of patients had levels ≥5 times the upper limit of normal; 70% (36/52) of the ALT flares occurred within 12 weeks after delivery. In subgroup analyses, the frequency of ALT elevation was similar among the groups A vs B vs C (50.9% [27/53] vs 58.3% [14/24] vs 40.7% [11/27], respectively; P  = .447), as well as the mean peak ALT level (108.4/74.1/126.7 U/L in groups A/B/C, respectively; P = .291). Although postpartum ALT flares were common for mothers with or without AVT during pregnancy, most cases of ALT elevation were mild to moderate. Our study observed that extending AVT to PPW 6 did not affect maternal outcomes and ATV should be discontinued at birth. Close monitoring is warranted as severe flares rarely occurred.

Maternal antiviral treatment safeguards infants from hepatitis B transmission in contingencies of delayed immunoprophylaxis

BACKGROUND & AIMS

Effectiveness of maternal antiviral prophylaxis in mother-to-child transmission of hepatitis B virus (HBV) has been extensively explored in studies where standard immunoprophylaxis is well secured to the newborns. This real-world study aims to test if maternal antiviral prophylaxis can safeguard the newborn when immunoprophylaxis administration was delayed or missed.

METHODS

Hepatitis B surface antigen-positive pregnant women were categorized into mothers with HBV DNA levels ≥2 × 10⁵ IU/mL receiving nucleos(t)ide analogue during the third trimester; mothers with HBV DNA levels ≥2 × 10⁵ IU/mL without antiviral treatment; and those with HBV DNA levels <2 × 10⁵ IU/mL without antiviral treatment. The immunoprophylaxis procedure was collected and verified by the delivery medical document and logbook of biological product usage. The primary end point was the rate of chronic HBV infection (CHB) in infants.

RESULTS

From 2011 to 2017, 251 mother-child pairs were enrolled. Among 187 infants of mothers with HBV DNA levels ≥2 × 10⁵ IU/mL, none developed CHB when mothers received antiviral treatment, as compared to 13.0% (10/77) of infants born to untreated mothers (P < .001). None of the infants of mothers with HBV DNA levels <2 × 10⁵ IU/mL were infected. Stratified by the time of immunoprophylaxis administration after birth, maternal antiviral prophylaxis predominately benefited infants who failed to receive immunoprophylaxis within 24 hours (100% [6/6] vs 0% [0/2], P = .036) and those who received delayed immunoprophylaxis between 2 and 24 hours (18.8% [3/16] vs 0% [0/32], P = .032).

CONCLUSIONS

Antiviral prophylaxis in high viraemic mothers is effective in contingencies of missed or delayed neonatal immunoprophylaxis.

Comparison of clinical practice guidelines for the management of chronic hepatitis B: When to start, when to change, and when to stop

Clinical practice guidelines are important for guiding the management of specific diseases by medical practitioners, trainees, and nurses. In some cases, the guidelines are utilized as a reference for health policymakers in controlling diseases with a large public impact. With this in mind, practice guidelines for the management of chronic hepatitis B (CHB) have been developed in the United States, Europe, and Asian-Pacific regions to suggest the best-fit recommendations for each social and medical circumstance. Recently, the Korean Association for the Study of the Liver published a revised version of its clinical practice guidelines for the management of CHB. The guidelines included updated information based on newly available antiviral agents, the most recent opinion on the initiation and cessation of treatment, and updates for the management of drug resistance, partial virological response, and side effects. Additionally, CHB management in specific situations was comprehensively revised. This review compares the similarities and differences among the various practice guidelines to identify unmet needs and improve future recommendations.

Hepatitis B Infection and Mother-to-Child Transmission in Haiphong, Vietnam: A Cohort Study with Implications for Interventions

Background

There is little data available on HBV infection and mother-to-child transmission (MTCT) in Vietnam.

Objective

This study is aimed at assessing the prevalence of HBV infection and the current situation of MTCT in Haiphong, Vietnam.

Methods

A transversal survey of 1721 pregnant women followed by an observational prospective cohort study of 183 HBV-infected women was conducted at Haiphong Gyneco-Obstetric Hospital. Women were followed up up to 12-month postpartum; use of prevention measures and the MTCT rate were evaluated. HBV infection in children was defined by a HBsAg-positive test at 12 months of age.

Results

At baseline, 183 of 1721 pregnant women (10.6%) tested HBsAg positive. Among them, 23.0% were HBeAg positive, 26.2% had a detectable load of HBV DNA, and 13.1% had a HBV DNA load ≥ 200,000 IU/mL. All women underwent MTCT prevention antiviral therapy. At delivery, 98.9% of newborns receive a HBV vaccine birth dose, and 82% received HBIG. At 12 months of age, 94.7% have received the scheduled HBV vaccines. Eight percent of infants born from followed-up women were HBsAg positive. The mother's HBeAg-positive status was associated with a higher risk of HBV infection in infants.

Conclusion

The HBV prevalence and MTCT rates are high in Haiphong. A strong national plan to increase the access to preventive measures and to monitor results is needed in order to decrease this prevalence.

Efficacy and safety of antiviral prophylaxis during pregnancy to prevent mother-to-child transmission of hepatitis B virus: a systematic review and meta-analysis

BACKGROUND

To eliminate mother-to-child transmission (MTCT) of hepatitis B virus (HBV), peripartum antiviral prophylaxis might be required for pregnant women infected with HBV who have a high risk of MTCT despite infant immunoprophylaxis. We aimed to determine the efficacy and safety of peripartum antiviral prophylaxis to inform the 2020 WHO guidelines.

METHODS

In this systematic review and meta-analysis, we searched PubMed, Embase, Scopus, CENTRAL, CNKI, and Wanfang for randomised controlled trials and non-randomised studies of peripartum antiviral prophylaxis versus placebo or no prophylaxis, with no language restriction, published from database inception until March 28, 2019. We used search terms covering HBV, antiviral therapy, and pregnancy. We included studies that enrolled pregnant women with chronic infection with HBV who received antiviral prophylaxis anytime during pregnancy; that included any of the following antivirals: adefovir, emtricitabine, entecavir, lamivudine, telbivudine, tenofovir alafenamide fumarate, and tenofovir disoproxil fumarate; and that reported the following outcomes: MTCT, indicated by infant HBsAg positivity or HBV DNA positivity, or both, at age 6-12 months, and any infant or maternal adverse events. Two reviewers independently extracted data. Our primary endpoint was MTCT based on infant HBsAg positivity. We assessed pooled odds ratios (ORs) of the efficacy of peripartum antiviral prophylaxis to reduce the risk of MTCT. We assessed safety of prophylaxis by pooling risk differences. The protocol for the systematic review was pre-registered in PROSPERO, CRD42019134614.

FINDINGS

Of 7463 articles identified, 595 articles were eligible for full-text review and 129 studies (in 157 articles) were included. The following antivirals were assessed in the meta-analysis: tenofovir disoproxil fumarate 300 mg (19 studies, with 1092 mothers and 1072 infants), lamivudine 100-150 mg (40 studies, with 2080 mothers and 2007 infants), and telbivudine 600 mg (83 studies, with 6036 mothers and 5971 infants). The pooled ORs for randomised controlled trials were similar, at 0·10 (95% CI 0·03-0·35) for tenofovir disoproxil fumarate, 0·16 (0·10-0·26) for lamivudine, and 0·14 (0·09-0·21) for telbivudine. The pooled ORs in non-randomised studies were 0·17 (0·10-0·29) for tenofovir disoproxil fumarate, 0·17 (0·12-0·24) for lamivudine, and 0·09 (0·06-0·12) for telbivudine. We found no increased risk of any infant or maternal safety outcomes after peripartum antiviral prophylaxis.

INTERPRETATION

Peripartum antiviral prophylaxis is highly effective at reducing the risk of HBV MTCT. Our findings support the 2020 WHO recommendation of administering antivirals during pregnancy, specifically tenofovir disoproxil fumarate, for the prevention of HBV MTCT.

FUNDING

World Health Organization.

Hepatitis B reactivation: diagnosis and management

INTRODUCTION

Hepatitis B virus (HBV) reactivation can be induced by treatments that attenuate the immunological control over HBV, leading to increased morbidity and mortality. The risk of HBV reactivation is determined by host immunity, viral factors, and the type and dose of treatments. Nevertheless, the risk of HBV reactivation for a growing number of novel therapies remains uncertain and needs to be carefully examined. Identification of patients at risk and administration of prophylactic antiviral agents are critical to prevent HBV reactivation. Early diagnosis and initiation of antiviral treatment are the keys to avoid devastating outcomes.

AREA COVERED

We summarized the latest evidence and recommendations for risk stratification, early diagnosis, prophylaxis, and management of HBV reactivation.

EXPERT OPINION

Universal screening, adequate prophylaxis, and close monitoring are essential for the prevention of HBV reactivation. Risk stratification of patients at risk with appropriate antiviral prophylaxis can prevent HBV reactivation effectively. Several emerging biomarkers have been proved to help determine the risk precisely. Early detection and timely administration of antiviral agents are crucial for management. Further studies on the precision of risk stratification as well as the optimal duration of prophylaxis and treatment are needed to establish an individualized strategy.

Efficacy and safety of telbivudine treatment for the prevention of HBV perinatal transmission

To observe the efficacy of telbivudine in chronic hepatitis B (CHB) women with high viral load during pregnancy and the long-term effects on intelligence, growth, and development of the newborns.A total of 87 patients were included. Forty-two patients received telbivudine orally 600 mg per day and treatment initiated from 12 weeks after gestation until the 12th postpartum week. Forty-five patients were untreated according to principle of informed consent. All infants received injection of hepatitis B immune globulin (HBIG; 200 IU) and were vaccinated with recombinant HBV vaccine. Wechsler preschool intelligence scale was used to assess mental and neuropsychological developments of these children till they were 6 years old. Data including serum HBV DNA viral load, Apgar score, and scores of Wechsler preschool intelligence scale were analyzed and compared.Levels of both serum HBV DNA and ALT in patients who received telbivudine were significantly decreased at the 12th week after delivery, compared with baseline levels (P < .01). No significant changes were observed in patients not receiving telbivudine (P > .05). Serum HBV DNA and ALT levels at the 12th week after delivery in the telbivudine group were significantly lower than those of patients without telbivudine (P < .01). The serum HBsAg-positive rate in neonates 7 months of age was 0%, which was significantly lower than that in control group (11.11%) (P < .05). No statistical differences were observed between the 2 groups regarding maternal cesarean section rate, adverse pregnancy rate, postpartum bleeding rate, neonatal body mass, Apgar score, neonatal malformation incidence, or intelligence development of newborn.Telbivudine is effective to reduce the viral load in CHB mothers with high viral load and could lower the perinatal transmission rate. Both mental and physical development in neonates with exposure to telbivudine during perinatal period were similar to those without telbivudine exposure.

Nanopore sequencing from extraction-free direct PCR of dried serum spots for portable hepatitis B virus drug-resistance typing

BACKGROUND

Effective drug regimens for the treatment of hepatitis B virus (HBV) infections are essential to achieve the World Health Organisation commitment to eliminate viral hepatitis by 2030. Lamivudine (3TC) is widely used in countries with high levels of chronic HBV, however resistance has been shown to occur in up to 50 % of individuals receiving continuous monotherapy for 4 years. Telbivudine (LdT) is now more commonly used in place of lamivudine but is ineffective against 3TC-resistant HBV. Genotyping and identification of resistanceassociated substitutions (RAS) is not practical in many locations.

OBJECTIVES

A novel assay was designed to enable HBV genotyping and characterisation of resistance mutations directly from serum samples stored on filter paper, using Sanger and MinION sequencing.

STUDY DESIGN

The assay was applied to a cohort of 30 samples stored on filter paper for several years with HBV viral loads ranging from 8.2 × 10⁸ to 635 IU/mL. A set of 6 high-titre samples were used in a proof-of-principle study using the MinION sequencer.

RESULTS

The assay allowed determination of HBV genotype and elucidation of RAS down to 600 IU/mL using a 550bp amplicon. Sequencing of a 1.2 kb amplicon using a MinION sequencer gave results consistent with Sanger sequencing and allowed the identification of minor populations of variants.

CONCLUSIONS

We present two approaches for reliable HBV sequencing and RAS identification using methods suitable for resource-limited environments. This is the first demonstration of extraction-free DNA sequencing direct from DSS using MinION and these workflows are adaptable to the investigation of other DNA viruses.

Prevention strategies of mother-to-child transmission of hepatitis B virus (HBV) infection

Chronic hepatitis B virus (HBV) infection caused by mother-to-child transmission (MTCT, also known as vertical transmission) during the perinatal period is a major public health problem worldwide. Despite the availability of the combined active-passive immunization with a hepatitis B vaccine and hepatitis B immunoglobulin after birth, about 9% of newborns are still infected with HBV, especially those born to hepatitis B e antigen (HBeAg)-positive mothers. Currently, the management of HBV infection during pregnancy remains controversial. This article briefly reviews the recent advances in the epidemiology of HBV, immunization against it, and management strategies in the third trimester.

Tenofovir plus hepatitis B immunoglobulin treatment resulted in a rapid HBV DNA load decline in high-risk pregnant women who missed the optimal time window of antiviral prophylaxis

BACKGROUND

Tenofovir disoproxil fumarate (TDF) administration in the third trimester for pregnant women with high HBV DNA load has been accepted as a wise practice to prevent mother-to-infant transmission (MTIT). However, for those women who missed the optimal time window of antiviral prophylaxis, this treatment is lacking in the current clinical guidelines.

METHODS

Forty-eight pregnant women who did not receive antiviral prophylaxis before 28 weeks of gestation were screened and were administrated with TDF plus hepatitis B immunoglobulin (HBIG; TDF+HBIG group) or TDF alone (TDF group). HBV DNA inhibition and the safety profile were compared between two groups.

RESULTS

A decline of HBV DNA load was observed in both groups after a short period of treatment, and no infant had MTIT. However, compared with the TDF group, the speed of HBV DNA load decline was more rapid (P=0.002) and a much more striking HBV DNA load decline in the first 4 weeks of treatment was exhibited in the TDF+HBIG group (P=0.001). The percentages of mothers with HBV DNA <4 log₁₀ IU/ml and 3 log₁₀ IU/ml at delivery were both much higher in the TDF+HBIG group than the TDF group (P=0.034 and 0.024, respectively). TDF and HBIG were found to be well-tolerated with no safety concerns in the mothers and their infants.

CONCLUSIONS

TDF plus HBIG treatment resulted in a rapid HBV DNA load decline in high-risk women who missed the optimal time window of antiviral prophylaxis in pregnancy, which potentially protected infants from HBV infection.

Efficacy and Safety of Lamivudine or Telbivudine in Preventing Mother-to-Child Transmission of Hepatitis B Virus: A Real-World Study

Background

There are few large sample studies evaluating the safety and efficacy of lamivudine (LAM) or telbivudine (LdT) in preventing hepatitis B mother-to-child transmission (MTCT) in highly viremic mothers in the third trimester of pregnancy in real-world settings. The purpose of this study was to analyze a large sample size of HBV-infected mothers to better understand the safety and efficacy of LAM and LdT under the aforementioned criteria.

Methods

During the period of November 2008 to November 2017, we retrospectively enrolled mothers with HBV DNA > 1 × 10⁶ IU/mL who received LAM or LdT during the third trimester of pregnancy and compared them to untreated mothers. All mothers were divided into the three following groups: the LAM group, the LdT group, and the control group.

Results

A total of 2624 HBV-infected mothers were enrolled in the study, with 363 in the LAM group, 1283 in the LdT group, and 978 in the control group. The MTCT rates were significantly lower in the LAM or LdT group than that in the control group (0.4% or 0.3% versus 9.0%, P < 0.001). Infants born to untreated mothers had a significantly higher risk of HBV infection (OR = 28.6, 95% CI: 10.4–78.7, P < 0.001). There were no significant differences in perinatal complications between the three groups (P > 0.05). There were also no differences for gestational age or infants' height, weight, Apgar scores, or birth defect rates. Postpartum discontinuation of antiviral therapy did not seem to increase the risk of postpartum alanine aminotransferase (ALT) flare.

Conclusion

LAM or LdT treatment initiated in the third trimester for mothers with HBV DNA > 1 × 10⁶ IU/mL was equally safe and effective in preventing MTCT.

A Real-world Prospective Study of Mother-to-child Transmission of HBV in China Using a Mobile Health Application (Shield 01)

Background and Aims: The World Health Organization (WHO) Western Pacific Region set a target of eliminating mother-to-child transmission (MTCT) of hepatitis B virus (HBV) by 2030. To assess the feasibility of this target in China, we carried out an epidemiological study to investigate the status quo of MTCT in the real-world setting. Methods: One thousand and eight hepatitis B surface antigen-positive pregnant women were enrolled at 10 hospitals. Immunoprophylaxis was administered to infants. In addition, mothers with HBV DNA level >2,000,000 IU/mL were advised to initiate antiviral therapy during late pregnancy. A health application called SHIELD was used to manage the study. Results: Nine hundred and five of the enrolled mothers, with 924 infants, completed the follow-up. Birth-dose hepatitis B vaccine and hepatitis B immunoglobulin were received by 99.7% and 99.7% of infants, respectively, within 24 h after birth. There were 446 mothers who received antiviral therapy, including 72.3% of the mothers with HBV DNA level >2,000,000 IU/mL and 21.0% of the mothers with HBV DNA level <2,000,000 IU/mL. Eight infants were infected with HBV. The overall rate of MTCT was 0.9%. Birth defects were rare (0.5% among infants with maternal antiviral exposure versus 0.7% among infants without exposure; p=1.00). Conclusions: The MTCT rate was lower than the WHO Western Pacific Region elimination MTCT target in this real-world study, indicating that a comprehensive management composed of immunoprophylaxis to infants and antiviral prophylaxis to mothers may be a feasible strategy to achieve the 2030 WHO elimination goal.

Serum alanine aminotransferase flares in chronic hepatitis B infection: the good and the bad

Chronic hepatitis B virus (HBV) infection follows a dynamic and variable course. At different stages in the disease, hepatitis flares might occur, which can be challenging to predict and manage. Flares are believed to be primarily immune-mediated and might mark transitions to inactive disease or clearance of infection, but in certain scenarios they might also lead to hepatic decompensation or death. As such, understanding of the clinical significance of flares in different patient populations and different scenarios is important for optimal management. In this Review, we summarise what is known about flares in different stages of chronic HBV infection; describe flares in the context of the natural history of chronic infection; summarise the immunological mechanisms underlying flares, and describe flares in different clinical scenarios. Each section reviews existing knowledge and highlights key unanswered questions that need to be addressed to improve the understanding of flares, hopefully providing insights into their pathogenesis that can be used to improve current clinical management and ideally to further develop new curative therapeutic approaches for HBV infection. We also propose a working definition of an ALT flare to facilitate future research.