Call to Action: Prevention of Mother-to-Child Transmission of Hepatitis B in Africa

[Frequency of drug resistance and immune escape mutations in the hepatitis B virus genome detected in pregnant women in the Republic of Guinea]

The aim of the work is to assess the prevalence of hepatitis B virus drug resistance mutations and immune escape mutations in pregnant women in the Republic of Guinea.

MATERIALS AND METHODS

Blood plasma samples obtained from 480 pregnant women from different regions of the Republic of Guinea with laboratory-confirmed viral hepatitis B were studied. Nucleotide sequences for genotype identification and mutation detection were obtained using nested-PCR followed by Sanger sequencing, based on overlapping pairs of primers spanning the complete genome of the virus.

RESULTS AND DISCUSSION

In the examined group, the viral genotype E was the most prevalent (92.92%) compared with subgenotypes A1 (1.67%), A3 (1.46%), D1 (0.63%), D2 (1.04%) and D3 (2.29%). Among the examined HBV-infected pregnant women, 188 (39.17%) had undetectable HBsAg. Drug resistance mutations were detected in 33 individuals, which amounted to 6.88%. The following mutations were found: S78T (27.27%), L80I (24.24%), S202I (15.15%), M204I/V (42.42%). The presence of polymorphic variants not described as drug resistant has also been shown in positions associated with the development of drug resistance to tenofovir, lamivudine, telbivudine and entecavir (L80F, S202I, M204R). When analyzing the MHR and the region of a determinant, mutations were detected in 318 (66.25%) of pregnant women. In 172 of them, which amounted to 54.09%, multiple mutations were found. The amino acid substitutions in 13 positions associated with HBsAg-negative hepatitis B and/or potentially affecting HBsAg antigenicity were identified.

CONCLUSION

The high prevalence of immune escape and drug resistance mutations potentially associated with false-negative result of HBsAg screening, prophylaxis failure, and virological failure of therapy that has been identified among treatment naive pregnant women imposes a serious problem.

Effect of prophylactic antiviral intervention on T cell immunity in hepatitis B virus-infected pregnant women

BACKGROUND

Antiviral intervention in hepatitis B virus (HBV)-infected pregnant women can effectively reduce mother-to-child transmission. However, the immunological characteristics of pregnant women with chronic HBV infection and the effects of antiviral intervention during pregnancy on maternal immune response remain unknown. We aimed to investigate these effects by comparing mothers who received antiviral intervention during pregnancy with those who did not.

METHODS

Pregnant women positive for hepatitis B surface antigen and hepatitis B e-antigen (HBsAg⁺ HBeAg⁺) were enrolled at delivery, including 34 received prophylactic antiviral intervention during pregnancy (AVI mothers) and 15 did not (NAVI mothers). T lymphocyte phenotypes and functions were analysed using flow cytometry.

RESULTS

At delivery, maternal regulatory T cell (Treg) frequency in AVI mothers was significantly higher than that in NAVI mothers (P < 0.002), and CD4⁺ T cells in AVI mothers displayed a decreased ability to secrete IFN-γ (P = 0.005) and IL-21 (P = 0.043), but an increased ability to secrete IL-10 and IL-4 (P = 0.040 and P = 0.036), which represented a higher Treg frequency, enhanced Th2 response and suppressed Th1 response. Treg frequency among AVI mothers was correlated negatively with serum HBsAg and HBeAg levels. After delivery, the ability of CD4⁺ T cells or CD8⁺ T cells to secrete IFN-γ or IL-10 was similar and no significant difference in Treg frequency was found between the two groups.

CONCLUSIONS

Prophylactic antiviral intervention during pregnancy has an effect on T cell immunity in pregnant women, which was characterised by increased maternal Treg frequency, enhanced Th2 response and suppressed Th1 response at delivery.

Participant perspectives to improve tenofovir adherence in the prevention of mother-to-child transmission of hepatitis B virus in Kinshasa, DRC

Prevention of mother-to-child transmission (PMTCT) programs for hepatitis B virus (HBV) are critical to reach the World Health Organization's 2030 HBV elimination goals. Despite demonstrated feasibility utilizing HIV infrastructure, HBV PMTCT programs are not implemented in many African settings, including in the Democratic Republic of Congo (DRC). In a previous pilot of HBV PMTCT implementation in DRC's capital, Kinshasa, we observed low TDF metabolite levels at delivery among women with high-risk HBV who were given tenofovir disoproxil fumarate (TDF) antiviral therapy. As such, we conducted qualitative interviews with women who received TDF to understand facilitators and barriers of medication adherence. We used a modified Information-Motivation-Behavioral Skills model (IMB+) as a framework for thematic content analysis. We found that trust in healthcare workers, familial support, and improved awareness of the disease and treatment options were important facilitators of TDF adherence; pill size, social stigma, and low HBV knowledge were barriers to adherence. While overall acceptance of TDF was high in this pilot, improved TDF adherence is needed in order to reach efficacious levels for preventing transmission from mothers to newborns. We suggest ongoing HBV sensitization within existing maternity and HIV care infrastructure would address gaps in knowledge and stigma identified here. Additionally, given the trust women have towards maternity center staff and volunteers, scaled HBV PMTCT interventions should include specific sensitization and education for healthcare affiliates, who currently receive no HBV prevention or information in DRC. This study is timely as TDF, particularly future long-acting formulations, could be considered as an alternate rather than adjuvant to birth-dose vaccination for HBV PMTCT in sub-Saharan Africa.

Global Disparities in Hepatitis B Elimination-A Focus on Africa

In 2016, WHO member states at the World Health Assembly adopted a Global Health Sector Strategy that included a policy of eliminating viral hepatitis. Clear targets were established to assist in achieving this by 2030. The strategy, while achievable, has exposed existing global disparities in healthcare systems and their ability to implement such policies. Compounding this, the regions with most disparity are also those where the hepatitis B prevalence and disease burden are the greatest. Foundational to hepatitis B elimination is the identification of both those with chronic infection and crucially pregnant women, and primary prevention through vaccination. Vaccination, including the birth dose and full three-dose coverage, is key, but complete mother-to-child transmission prevention includes reducing the maternal hepatitis B viral load in the third trimester where appropriate. Innovations and simplified tools exist in order to achieve elimination, but what is desperately required is the will to implement these strategies through the support of appropriate investment and funding. Without this, disparities will continue.

Hepatitis B virus infection and hepatocellular carcinoma in sub-Saharan Africa: Implications for elimination of viral hepatitis by 2030?

Elimination of viral hepatitis in sub-Saharan Africa by 2030 is an ambitious feat. However, as stated by the World Health Organization, there are unprecedented opportunities to act and make significant contributions to the elimination target. With 60 million people chronically infected with hepatitis B virus (HBV) of whom 38800 are at risk of developing highly fatal hepatocellular carcinoma (HCC) every year, sub-Saharan Africa faces one of the greatest battles towards elimination of viral hepatitis. There is a need to examine progress in controlling the disproportionate burden of HBV-associated HCC in sub-Saharan Africa within the context of this elimination target. By scaling-up coverage of hepatitis B birth dose and early childhood vaccination, we can significantly reduce new cases of HCC by as much as 50% within the next three to five decades. Given the substantial reservoir of chronic HBV carriers however, projections show that HCC incidence and mortality rates in sub-Saharan Africa will double by 2040. This warrants urgent public health attention. The trends in the burden of HCC over the next two decades, will be determined to a large extent by progress in achieving early diagnosis and appropriate linkage to care for high-risk chronic HBV infected persons.

Elimination of Viral Hepatitis in Low and Middle-Income Countries: Epidemiological Research Gaps

PURPOSE OF REVIEW

The purpose of our review was to summarize current recommendations on testing strategies, antiviral therapy eligibility and monitoring, and prevention of mother-to-child transmission of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections, and to highlight major research gaps in low and middle-income countries (LMIC), with a particular focus on sub-Saharan Africa (SSA).

RECENT FINDINGS

While data on the prevalence of HBV and HCV infections in LMIC are increasing, current knowledge on liver-related complications as well as on treatment outcomes remains limited. Furthermore, very little information is available on the feasibility and cost-effectiveness of large-scale testing and management strategies in high-prevalence settings. The availability of policy-relevant data is particularly scarce in SSA, which accounts for a significant part of the global burden of chronic viral hepatitis.

SUMMARY

Current recommendations on the management and monitoring of chronic viral hepatitis rely mainly on data from high-income settings. The global elimination of viral hepatitis will only be achieved if prevention, testing, and treatment strategies tailored to specific LMIC are implemented. In order to inform scalable and cost-effective interventions, dedicated research initiatives have to be undertaken. Future studies will have to include the evaluation of innovative testing strategies, the validation of simplified methods to diagnose liver cirrhosis and hepatocellular carcinoma, and the monitoring of long-term treatment outcomes and toxicity. In addition, national plans to achieve the elimination of HBV mother-to-child transmission are urgently needed, including effective ways to test pregnant women, treat those who are eligible, and ensure birth dose vaccination is given to all newborns.

Antenatal hepatitis B screening in Nigeria: A comparative analysis with syphilis and HIV

Nigeria has adopted routine screening of pregnant women for hepatitis B virus (HBV) as part of the interventions to eliminate its vertical transmission. However, there is a dearth of evidence on the coverage of routine antenatal HBV screening as recommended in the national guidelines. This study examined the antenatal HBV screening rate and the positivity rate compared with syphilis and HIV. We conducted a descriptive analysis of the 2019 national HIV/AIDS health sector data. The study included approximately 2.8 million pregnant women who received antenatal care (ANC) in over 6000 health facilities providing prevention of mother-to-child transmission of HIV services in Nigeria. Of the ANC clients, 0.2 million (7.2%) were screened for HBV. At the zonal level, the South West had the highest HBV screening rate (19%), while the lowest rate was in the North East (2.5%). The percentage of pregnant women screened for HBV was lower than those screened for syphilis (16.3%) and HIV (90.3%). Among those screened for HBV, the positivity rate was 5%. The HBV positivity rate ranged from 8.5% in the North Central zone to 1.3% in the South East zone. The positivity rates for syphilis and HIV were 0.4% and 0.5%, respectively. Our results indicate a low antenatal HBV screening rate and a wide disparity compared with HIV and syphilis. This finding highlights the need to understand and address the barriers affecting routine antenatal HBV screening and to strengthen the integration of HBV services into the HIV program in Nigeria.

Hepatitis B-related hepatocellular carcinoma: surveillance strategy directed by immune-epidemiology

Hepatitis B infection (HBV) is one of the most common causes of hepatocellular carcinoma (HCC) worldwide. The age of occurrence, prognosis and incidence vary dramatically depending on the region of the world. This geographic variation is largely dependent on the contrasting incidence of HBV, age of transmission of the virus, the timing of integration into the human genome, and different HBV genotypes, as well as environmental factors. It results in a wide difference in viral interaction with the immune system, genomic modulation and the consequent development of HCC in an individual. In this review, we describe many factors implicated in HCC development, provide insight regarding at-risk populations and explain societal recommendations for HCC surveillance in persons living with HBV in different continents of the world.

Eliminating mother-to-child transmission of human immunodeficiency virus, syphilis and hepatitis B in sub-Saharan Africa

Triple elimination is an initiative supporting the elimination of mother-to-child transmission of three diseases – human immunodeficiency virus (HIV) infection, syphilis and hepatitis B. Significant progress towards triple elimination has been made in some regions, but progress has been slow in sub-Saharan Africa, the region with the highest burden of these diseases. The shared features of the three diseases, including their epidemiology, disease interactions and core interventions for tackling them, enable an integrated health-systems approach for elimination of mother-to-child transmission. Current barriers to triple elimination in sub-Saharan Africa include a lack of policies, strategies and resources to support the uptake of well established preventive and treatment interventions. While much can be achieved with existing tools, the development of new products and models of care, as well as a prioritized research agenda, are needed to accelerate progress on triple elimination in sub-Saharan Africa. In this paper we aim to show that health systems working together with communities in sub-Saharan Africa could deliver rapid and sustainable results towards the elimination of mother-to-child transmission of all three diseases. However, stronger political support, expansion of evidence-based interventions and better use of funding streams are needed to improve efficiency and build on the successes in prevention of mother-to-child transmission of HIV. Triple elimination is a strategic opportunity to reduce the morbidity and mortality from HIV infection, syphilis and hepatitis B for mothers and their infants within the context of universal health coverage.

Prevalence of hepatitis B among childbearing women and infant born to HBV-positive mothers in Togo

Background

Hepatitis B virus (HBV) infection is a public health problem in Togo and transmission to the child occurs mainly during childbirth. The objective of this study was to estimate the prevalence of HBV among childbearing women and infants born to HBV positive mothers in Togo.

Methods

A national cross-sectional study was carried out in six cities in Togo in the six health regions in Togo. Mother-child pairs were recruited from immunization centers or pediatric wards in Lomé, Tsévié, Atakpamé, Sokodé, Kara and Dapaong in 2017. Women aged 18 and over with one child of at least 6 months old were included. A standardized questionnaire was used for data collection and HBV screening was performed using Determine® rapid tests. The prevalence of HBV, defined by a positive HBV surface antigen (HBsAg), was estimated in mothers and then in infants of mothers who were positive for HBsAg. Logistic regression model was performed to identify risk factors for HBsAg positivity in mothers.

Results

A total of 2105 mothers-pairs child were recruited. The median age of mothers and infants was 29 years, interquartile range (IQR) [25–33] and 2.1 years, IQR [1–3] respectively. About 35% of women were screened for HBV during antenatal care and 85% of infants received three doses of HBV immunization. Among mothers, the prevalence of HBV was 10.6, 95% confidence interval (95% CI) [9.4–12.0%], and 177 had detectable HBV viral load (> 10 IU/mL). Among mothers with positive HBsAg, three infants also had positive HBsAg, a prevalence of 1.3, 95% CI [0.2–3.8%]. In multivariable analysis, HIV-infection (aOR = 2.19; p = 0.018), having at least three pregnancies (aOR = 1.46; p = 0.025) and living in Tsévié (aOR = 0.31; p < 0.001) compared to those living in Lomé, were associated to HBV infection in mothers.

Conclusion

In this study, one out of 10 childbearing women were infected with HBV, but less than 2% of infant born to HBV positive mothers under 5 years’ old who received immunization under the Expanded Program on Immunization were infected. Improving antenatal screening and providing targeted interventions in babies could help eliminate HBV in Togo.

Prevalence and molecular characterization of occult hepatitis B virus in pregnant women from Gondar, Ethiopia

BACKGROUND: The greatest risk of chronic hepatitis B (CHB) is from mother-to-child transmission. Approximately 20% of individuals in sub-Saharan Africa are hepatitis B virus (HBV) surface antigen–positive (HBsAg+), but the prevalence of occult hepatitis B (OHB) is unknown. Aim: This study investigated CHB and OHB prevalence and viral variants in a cohort of pregnant women in Gondor, Ethiopia. METHODS: Patients were prospectively recruited from the University of Gondar Hospital ( N = 200; median age 27 [inter-quartile range] 8.3y) from March through June 2016. Data were collected using an investigator-administered questionnaire. Plasma was tested for HBsAg and HBV core antibody (anti-HBc), and HBV genotype and presence of HBV variants (ie, vaccine escape mutants [VEMs]) were determined by polymerase chain reaction, Sanger sequencing, and phylogenetic analysis. RESULTS: Of women tested, 1% (2/200) were HBsAg+; 26.8% (47/182) of HBsAg-negative patients were anti-HBc+, of whom 37/47 (78.7%) had detectable HBV DNA. The overall rate of OHB was 20.3%. Both HBsAg+ cases were HBV genotype D, and 36/37 (97.3%) of OHB individuals were genotype D. None carried VEM, but both HBsAg+ cases and 32/37 (86.5%) of the OHB cases showed lamivudine-resistant mutations. CONCLUSIONS: Twenty-seven percent of pregnant women in this cohort showed evidence of CHB or prior HBV exposure (ie, HBsAg+ or anti-HBc+) and clinically relevant HBV variants. Data from this single-centre study suggests high HBV prevalence, reinforcing the World Health Organization’s recommendation for universal prenatal HBV screening and infant vaccination.

Infection by Hepatitis Delta Virus

Hepatitis delta virus (HDV) and hepatitis B virus (HBV) are blood-borne viruses that infect human hepatocytes and cause significant liver disease. Infections with HBV are more damaging when there is a coinfection with HDV. The genomes and modes of replication of these two viruses are fundamentally different, except for the fact that, in nature, HDV replication is dependent upon the envelope proteins of HBV to achieve assembly and release of infectious virus particles, ones that use the same host cell receptor. This review focuses on what has been found of the various ways, natural and experimental, by which HDV particles can be assembled and released. This knowledge has implications for the prevention and treatment of HDV infections, and maybe for an understanding of the origin of HDV.

Hepatitis B virus seroepidemiology data for Africa: Modelling intervention strategies based on a systematic review and meta-analysis

BACKGROUND

International Sustainable Development Goals (SDGs) for elimination of hepatitis B virus (HBV) infection set ambitious targets for 2030. In African populations, infant immunisation has been fundamental to reducing incident infections in children, but overall population prevalence of chronic hepatitis B (CHB) infection remains high. In high-prevalence populations, adult catch-up vaccination has sometimes been deployed, but an alternative Test and Treat (T&T) approach could be used as an intervention to interrupt transmission. Universal T&T has not been previously evaluated as a population intervention for HBV infection, despite high-profile data supporting its success with human immunodeficiency virus (HIV).

METHODS AND FINDINGS

We set out to investigate the relationship between prevalence of HBV infection and exposure in Africa, undertaking a systematic literature review in November 2019. We identified published seroepidemiology data representing the period 1995-2019 from PubMed and Web of Science, including studies of adults that reported prevalence of both hepatitis B surface antigen (HBsAg; prevalence of HBV infection) and antibody to hepatitis B core antigen (anti-HBc; prevalence of HBV exposure). We identified 96 studies representing 39 African countries, with a median cohort size of 370 participants and a median participant age of 34 years. Using weighted linear regression analysis, we found a strong relationship between the prevalence of infection (HBsAg) and exposure (anti-HBc) (R2 = 0.45, p < 0.001). Region-specific differences were present, with estimated CHB prevalence in Northern Africa typically 30% to 40% lower (p = 0.007) than in Southern Africa for statistically similar exposure rates, demonstrating the need for intervention strategies to be tailored to individual settings. We applied a previously published mathematical model to investigate the effect of interventions in a high-prevalence setting. The most marked and sustained impact was projected with a T&T strategy, with a predicted reduction of 33% prevalence by 20 years (95% CI 30%-37%) and 62% at 50 years (95% CI 57%-68%), followed by routine neonatal vaccination and prevention of mother to child transmission (PMTCT; at 100% coverage). In contrast, the impact of catch-up vaccination in adults had a negligible and transient effect on population prevalence. The study is constrained by gaps in the published data, such that we could not model the impact of antiviral therapy based on stratification by specific clinical criteria and our model framework does not include explicit age-specific or risk-group assumptions regarding force of transmission.

CONCLUSIONS

The unique data set collected in this study highlights how regional epidemiology data for HBV can provide insights into patterns of transmission, and it provides an evidence base for future quantitative research into the most effective local interventions. In combination with robust neonatal immunisation programmes, ongoing PMTCT efforts, and the vaccination of high-risk groups, diagnosing and treating HBV infection is likely to be of most impact in driving advances towards elimination targets at a population level.

Modelling cost-effectiveness of tenofovir for prevention of mother to child transmission of hepatitis B virus (HBV) infection in South Africa

BACKGROUND

International sustainable development goals for the elimination of viral hepatitis as a public health problem by 2030 highlight the need to optimize strategies for prevention, diagnosis and treatment of hepatitis B virus (HBV) infection. An important priority for Africa is to have affordable, accessible and sustainable prevention of mother to child transmission (PMTCT) programmes, delivering screening and treatment for antenatal women and implementing timely administration of HBV vaccine for their babies.

METHODS

We developed a decision-analytic model simulating 10,000 singleton pregnancies to assess the cost-effectiveness of three possible strategies for deployment of tenofovir in pregnancy, in combination with routine infant vaccination: S1: no screening nor antiviral therapy; S2: screening and antiviral prophylaxis for all women who test HBsAg-positive; S3: screening for HBsAg, followed by HBeAg testing and antiviral prophylaxis for women who are HBsAg-positive and HBeAg-positive. Our outcome was cost per infant HBV infection avoided and the analysis followed a healthcare perspective.

RESULTS

Based on 10,000 pregnancies, S1 predicts 45 infants would be HBV-infected at six months of age, compared to 21 and 28 infants in S2 and S3, respectively. Relative to S1, S2 had an incremental cost of $3940 per infection avoided. S3 led to more infections and higher costs.

CONCLUSION

Given the long-term health burden for individuals and economic burden for society associated with chronic HBV infection, screening pregnant women and providing tenofovir for all who test HBsAg+ may be a cost-effective strategy for South Africa and other low/middle income settings.

Will Infant Hepatitis B Immunization Protect Adults?

Globally, infant hepatitis B virus (HBV) immunization programs are markedly reducing the rate of chronic HBV infections among children <5 years of age. Desirable improvements include increased birth dose coverage and better prevention of perinatal HBV transmission. Follow-up studies show that by the teenage years most of those immunized as infants have lost circulating anti-HBs antibody and some fail to respond to challenge HBV vaccination, implying loss of protection from infection. With high exposure to HBV, such individuals can develop breakthrough HBV infection but this rarely leads to chronic infection, the main goal of prevention programs. While longer-term follow-up studies into adulthood are needed, current evidence does not support a need for booster immunization of otherwise healthy teens or young adults.

Elimination of Vertical Transmission of Hepatitis B in Africa: A Review of Available Tools and New Opportunities

PURPOSE

This review article focuses on preventing vertical transmission of hepatitis B virus (HBV) among pregnant women living in sub-Saharan Africa (SSA), where disease is endemic and the estimated maternal HBV seroprevalence is >8%. Available interventions that have been studied in low- and middle-income countries are compared in terms of efficacy and effectiveness in clinical practice. Global disease-elimination targets, barriers to HBV-prevention efforts, and critical research gaps are discussed.

METHODS

A PubMed literature search in February 2018 identified relevant studies of interventions to reduce or prevent the transmission of HBV during pregnancy or in the peripartum period. Studies that focused on interventions that are currently available or could be made available in SSA were included. Trials conducted in SSA and other low-income countries were prioritized, although studies of interventions in middle- and high-income countries were included.

FINDINGS

Among 127 studies and reports included in the review, 60 included data from SSA. The most cost-effective intervention to reduce HBV infection rates in SSA is timely birth-dose vaccination followed by completion of the 3-dose infant-vaccination series. The identification and treatment of pregnant women with elevated HBV viral load to further reduce the risk for vertical transmission in SSA show promise, but efficacy and tolerability trials in Africa are lacking.

IMPLICATIONS

Scale-up of currently available tools is required to reach HBV disease-elimination goals in SSA. Many countries in SSA are in the process of rolling out national birth-dose vaccination campaigns; this roll out provides an opportunity to evaluate and improve processes in order to expand coverage. Early antenatal care, promotion of facility deliveries, and increased awareness of HBV prevention are also key components of prevention success. Future studies in SSA should identity an HBV-prevention package that is effective, well tolerated, and feasible and can be administered in the antenatal clinic and tailored to vertical-transmission risk.

A systematic review of hepatitis B virus (HBV) drug and vaccine escape mutations in Africa: A call for urgent action

International sustainable development goals for the elimination of viral hepatitis as a public health problem by 2030 highlight the pressing need to optimize strategies for prevention, diagnosis and treatment. Selected or transmitted resistance associated mutations (RAMs) and vaccine escape mutations (VEMs) in hepatitis B virus (HBV) may reduce the success of existing treatment and prevention strategies. These issues are particularly pertinent for many settings in Africa where there is high HBV prevalence and co-endemic HIV infection, but lack of robust epidemiological data and limited education, diagnostics and clinical care. The prevalence, distribution and impact of RAMs and VEMs in these populations are neglected in the current literature. We therefore set out to assimilate data for sub-Saharan Africa through a systematic literature review and analysis of published sequence data, and present these in an on-line database (https://livedataoxford.shinyapps.io/1510659619-3Xkoe2NKkKJ7Drg/). The majority of the data were from HIV/HBV coinfected cohorts. The commonest RAM was rtM204I/V, either alone or in combination with associated mutations, and identified in both reportedly treatment-naïve and treatment-experienced adults. We also identified the suite of mutations rtM204V/I + rtL180M + rtV173L, that has been associated with vaccine escape, in over 1/3 of cohorts. Although tenofovir has a high genetic barrier to resistance, it is of concern that emerging data suggest polymorphisms that may be associated with resistance, although the precise clinical impact of these is unknown. Overall, there is an urgent need for improved diagnostic screening, enhanced laboratory assessment of HBV before and during therapy, and sustained roll out of tenofovir in preference to lamivudine alone. Further data are needed in order to inform population and individual approaches to HBV diagnosis, monitoring and therapy in these highly vulnerable settings.

HIV treatment in pregnancy

Almost 25 years since antiretroviral therapy (ART) was first shown to prevent mother-to-child transmission of HIV, 76% of pregnant women living with HIV (over 1 million women) receive ART annually. This number is the result of successes in universal ART scale-up in low-income and middle-income countries. Despite unprecedented ART-related benefits to maternal and child health, challenges remain related to ART adherence, retention in care, and unequal access to ART. Implementation research is ongoing to understand and to address obstacles that lead to loss to follow-up. The biological mechanisms that underlie observed associations between antenatal ART and adverse outcomes in pregnancy and birth are not completely understood, with further research needed as well as strengthening of the systems to assess safety of antiretroviral drugs for the mother and HIV-exposed child. In the treat-all era, as duration of treatment and options for ART expand, pregnant women will remain a priority population for treatment optimisation to promote their health and that of their ART-exposed children.

Chronic and Occult Hepatitis B Virus Infection in Pregnant Women in Botswana

The hepatitis B virus (HBV) is a global problem; however, the burden of HBV infection in pregnant women in Botswana is unknown. We sought to determine the prevalence of chronic and occult HBV infection in human immunodeficiency virus (HIV)-infected and -uninfected pregnant women in Botswana. Samples from 752 pregnant women were tested for hepatitis B surface antigen (HBsAg), and HBsAg-positive samples were tested for hepatitis B e antigen (HBeAg) and HBV DNA load. Samples that were HBsAg negative were screened for occult HBV infection by determining the HBV DNA load. HBV genotypes were determined based on a 415-base-pair fragment of the surface gene. Among the 752 women tested during pregnancy or early postpartum, 16 (2.1%) (95% confidence interval (CI): 2.0–2.2) were HBsAg-positive. The prevalence of chronic HBV infection was higher (3.1%) among HIV-infected (95% CI: 3.0–3.2) compared with HIV-uninfected women (1.1%) (95% CI: 1.07–1.1, p = 0.057). Among the 622 HBsAg-negative women, the prevalence of occult HBV infection was 6.6% (95% CI: 6.5–6.7). Three of thirteen HBsAg-positive participants were HBeAg-positive, and all were HIV-negative. Of the 11 maternal samples successfully genotyped, five (45.5%) were genotype D3, five (45.5%) were genotype A1, and one was genotype E (9%). Low and similar proportions of HIV-infected and -uninfected pregnant women in Botswana had occult or chronic HBV infection. We identified a subset of HIV-negative pregnant women who had high HBV DNA levels and were HBeAg-positive, and thus likely to transmit HBV to their infants.