Long-term anti-HBs antibody persistence following infant vaccination against hepatitis B and evaluation of anamnestic response: a 20-year follow-up study in Thailand

Protection level of anti-hepatitis B vaccine and immunoglobulin in a pediatric Cameroonian population

Despite the availability for nearly twenty years of an effective vaccine, hepatitis B remains one of the most frequent viral diseases throughout the world. Mother-to-child transmission is one of the primary routes of transmission in children. To assess the vaccine response in children born to HBV infected mothers. HBsAg-positive consenting mothers registered in the antenatal care (ANC) service database of Centre Hospitalier Dominicain St-Martin de Porres, Yaounde were enrolled with their children. Socio-demographic characteristics were collected using a tested questionnaire. The 5 markers of hepatitis B were tested and the quantification of anti-HBsAg antibodies was done by indirect ELISA method. The data collected was analyzed using Microsoft excel and Epi-info softwares. Out of 5,996 women registered, 143 were identified as HBsAg positive (2.38% prevalence) and none was HBeAg positive. Of these 143 HBsAg positive women, 50 were enrolled in the study. Of the 50 positive mothers, 78 children were included with a mean age ± standard deviation of 2.33±2.86 years. No child was infected with HBV, but all have been exposed to the virus (HBeAb-positive). Overall 64 (82.05%) received at birth both anti-HBs immunoglobulin (HBIG) and a dose of vaccine, while 14 (17.95%) received only the birth dose of vaccine. 72 (92.31%) children received all three recommended doses of vaccine. Vaccine responders were 62.82% (above 10 IU/ml), while 37.18% of children were non-responders; representing a higher risk group if not boosted. The coverage of the anti-HBV vaccine in children in this study was 92.31%. The protection level of 62.82% is below the 95% recommended rate by WHO. The factors sustaining this suboptimal protection should be investigated.

Immunogenicity of the pentavalent DTwP-HB-Hib vaccine (Shan-5) used in the Thai Expanded Program on Immunization compared to the hexavalent DTaP-HB-Hib-IPV and DTwP-HB-Hib (Quinvaxem) vaccines administered to infants at 2, 4, 6 months of age

BACKGROUND

The pentavalent DTwP-HB-Hib (Shan-5) vaccine was first introduced into the Thailand Expanded Program on Immunization (EPI) in 2019. The Shan-5 vaccine is administered to infants at 2, 4, and 6 months of age, after initial vaccination with monovalent hepatitis B (HepB) and Bacillus Calmette-Guérin (BCG) vaccines at birth. This study compared the immunogenicity of the HepB, diphtheria, tetanus, and Bordetella pertussis antigens incorporated in the EPI Shan-5 vaccine versus the optional pentavalent (DTwP-HB-Hib) Quinvaxem and hexavalent (DTaP-HB-Hib-IPV) Infanrix-hexa vaccine.

METHODS

Three-dose Shan-5-vaccinated children were prospectively enrolled at the Regional Health Promotion Centre 5, Ratchaburi province, Thailand, between May 2020 and May 2021. Blood sampling was performed at months 7 and 18. The levels of HepB surface antibody (anti-HBs), anti-diphtheria toxoid (DT) IgG, anti-tetanus toxoid (TT) IgG, and anti-pertussis toxin (PT) IgG were evaluated using commercially available enzyme-linked immunoassays.

RESULTS

Anti-HBs levels of ≥10 mIU/mL were achieved in 100 %, 99.2 %, and 99.2 % of infants in the Shan-5 EPI group, hexavalent group and Quinvaxem group one month after four dose immunization (at 0, 2, 4, 6 months of age), respectively. The geometric mean concentrations of the EPI Shan-5 and hexavalent groups were comparable but were higher than those of the Quinvaxem group. At one month after primary vaccination (month 7), infants in the Shan-5 EPI group had significantly higher levels of anti-DT IgG, anti-TT IgG, and anti-PT IgG than infants in the hexavalent and Quinvaxem groups.

CONCLUSIONS

The immunogenicity of the HepB surface antigen in the EPI Shan-5 vaccine was similar to that achieved by the hexavalent vaccine, but was higher than that achieved by the Quinvaxem vaccine. The Shan-5 vaccine is highly immunogenic and generates robust antibody responses after primary immunization.

High prevalence of hepatitis B virus and low vaccine response in children and adolescents in Northeastern Brazil

Children have an increased likelihood of becoming carriers of the chronic hepatitis B virus. A total of 1,381 children and adolescents were assessed in five municipalities of Maranhao State, Brazil, for detection of anti-HBc, HBsAg and anti-HBs serologic markers and sociodemographic and behavioral features. Among those who were HBsAg negative and anti-HBc negative, the proportion of anti-HBs positives was calculated after the individuals had completed the vaccination schedule. The robust variance of the Poisson's regression model was used in order to have adjusted tables and calculate the prevalence ratio. Multivariate analysis was performed to identify the factors associated with the prevalence of anti-HBc with or without HBsAg and the vaccine response. It was observed that 163 children were anti-HBc positive and nine individuals were HBsAg positive. The factors associated with the infection were: municipality of residence (residing in Morros municipality or Humberto de Campos municipality), residence in a rural area, aged between 13 and 15 years old, and illicit drug use. The percentage of individuals who were anti-HBc negative and received all three doses of the vaccine was 48.5%. Among these, only 276 (38.9%) had antibodies at protective concentrations. In an adjusted analysis, Morros municipality presented an increased positivity of vaccine response (p < 0.001), and the age ranging between 6 and 10 years old presented a reduced frequency of response. This study reveals a high prevalence of current and past HBV infection within the targeted age group which, in addition to the low vaccination coverage and serological responses, raises concerns about the management of prevention measures, especially the quality of vaccination in these locations.

Targeted antiviral treatment of hepatitis B virus in culturally and linguistically diverse populations to achieve elimination targets in Australia

The majority of Australia's hepatitis B virus (HBV) burden is borne by culturally and linguistically diverse (CALD) populations, and antiviral treatment is the mainstay of intervention. Using modelling, we estimated the impact of targeted antiviral treatment scale-up and changes in migration on HBV-related mortality and HBV elimination in CALD populations in Australia. We fitted a deterministic mathematical model based on the natural history of HBV and the Australian migration effect in four CALD population groups according to country of birth. We used three antiviral treatment scale-up scenarios: baseline (9.3% coverage); intermediate (coverage of 80% of patients eligible for antiviral therapy by 2030); and optimistic (coverage of 20% of all patients living with HBV by 2022). Our model predicted that if the baseline treatment is followed between 2015 and 2030, the number of chronic HBV cases and HBV-related mortality will increase. Following the optimistic scale-up, the number of new HBV cases could be reduced by 78%, 73%, 74% and 83% in people born in Asia-Pacific, Europe, Africa and the Middle East, and Americas, respectively, between 2015 and 2030. An optimistic treatment scale-up could result in a 19.2%-24.5% reduction in HBV-related mortality and a 15%-25% reduction in HCC-related mortality in CALD populations between 2015 and 2030. In conclusion, our findings highlight that targeted antiviral treatment for CALD populations provides significant health system benefits by reducing HBV-related complications from cirrhosis and HCC. Expanded antiviral treatment programmes focusing on high-prevalence CALD populations may be an effective strategy to reduce HBV-related morbidity and mortality.

Seroprevalence of Hepatitis A, B and C Among a Sample of Refugees in Egypt: An Exploratory Survey

BACKGROUND

Estimating the prevalence of infectious diseases, including viral hepatitis, among refugees is important for evaluating their health needs and predicting the burden on the health system of the host country. This study aimed at estimating the seroprevalence of viral hepatitis among refugees in Egypt.

METHODS

This cross-sectional study involved a heterogeneous group of 501 refugees. Enzyme-linked immunosorbent assays were used to detect IgG antibodies against hepatitis A virus (HAV), B virus (HBV) surface antigen (anti-HBsAg), C virus (HCV), and HBV surface antigen (HBsAg).

RESULTS

Anti-HAV was the most prevalent marker (n = 482, 96.2%), followed by anti-HBs (n = 142, 28.3%) and HBsAg (n = 21, 4.2%), while only four refugees (0.8%) had positive anti-HCV IgG. Anti-HBs was higher in males (p < 0.05). Older refugees and non-working subjects had significantly higher seropositive rates of anti-HAV (p = 0.051 and p = 0.023, respectively), while students and those below 15 years of age had higher rates of anti-HBs (p < 0.05). Positive HBsAg results were associated with history of hepatitis (p < 0.001). Obese participants were more likely to be positive for HBsAg (p = 0.025) and anti-HBs (p < 0.05). Sudanese refugees had significantly higher rates of anti-HAV antibodies (p = 0.049), while Yemini refugees had significantly higher rates for HBsAg (p = 0.019) positivity. Residents of Dakahlia had significantly higher rates of anti-HAV (p = 0.008) and anti-HBs (p < 0.05). None of the studied risk factors was significantly associated with anti-HCV.

CONCLUSION

Refugees in Egypt have poor immunity against HBV with intermediate to high HBV and low HCV prevalence rates. Despite that 65% of refugees received the HAV vaccine, almost all had IgG anti-HAV, denoting previous infection.

Post-vaccination Immunity Against Hepatitis B Among Mongolian Adolescents and Youths

Background: Mongolia introduced vaccination against hepatitis B (HepB) in 1991, leading to a significant decline in the number of infections and mortality associated with the liver disease among this generation. However, the prevalence of hepatitis B virus (HBV) infection and mortality rates among people born before the vaccination program have not declined. Although several studies have been conducted in Mongolia since the introduction of the HepB immunization program, long-term immunity has not been studied at the national level. Objectives: This study aimed to determine the prevalence of HBV infection in adolescents and young adults who received HepB vaccinations at 0, 2, and 8 months after birth and to assess their post-vaccination immunity against hepatitis B. Methods: A population-based cross-sectional study was conducted between December 2016 and December 2018 and included a sample aged 10 to 27 years in Mongolia who had received HepB vaccination according to the national program. A total of 3591 individuals were randomly selected, and data were collected using a structured questionnaire. Blood samples were collected, and serum titers of hepatitis B surface antigen (HBsAg), antibody to HBsAg (anti-HBs), and antibody to hepatitis B core antigen (anti-HBc) were determined by a two-step sandwich chemiluminescent enzyme immunoassay. The age-specific geometric mean of anti-HBs was also estimated. Results: Overall, 98.3% of participants were vaccinated against HepB as infants, according to the interview. The majority had an inadequate anti-HBs titer, while 17.9% had an anti-HBs level of > 10 mIU/mL, of whom 5.7% had immunity induced by HBV infection. Up to 4% of children aged 10 - 19 years and an average of 8% of young adults were serologically positive for HBsAg. The geometric mean anti-HBs titer declined with age, from an average of 40.4 mIU/mL in 10-year-old children to 14.1 IU/mL in 27-year-old adults (P < 0.001). Conclusions: In Mongolia, a small proportion of the population aged 10 - 27 years is immune to HBV, and the geometric mean titer of anti-HBS tended to decrease with age. In order to attain long-term protection against HBV, booster vaccination in adulthood may be necessary.

Duration of Hepatitis B Vaccine-Induced Protection among Medical Students and Healthcare Workers following Primary Vaccination in Infancy and Rate of Immunity Decline

Since the introduction of hepatitis B virus (HBV) vaccines, the numbers of HBV infections and complications have significantly decreased. However, the evidence on whether primary vaccination of infants confers lifelong immunity varies. We aimed to assess long-term immunity among healthcare workers and medical students, and the rate of decline of HBV surface antigen antibodies (anti-HBs). Hepatitis B status among participants born after 1 January 1992 was reviewed at Chulabhorn Royal Academy, Thailand. Participants were stratified by intervals since primary vaccination. HBV immunity was determined and analyzed as anti-HBs decline rate in participants with multiple follow-ups. A total of 464 participants were analyzed, with a median age of 23. Protective immunity against HBV (anti-HBs ≥ 10 mIU/mL) at 16–20, 21–25 and 26–28 years post-primary vaccination was 28%, 51.7% and 60%, respectively. The overall declining rate of anti-HBs was −42.39 mIU/mL per year. Participants with anti-HBs levels of >100–1000 mIU/mL at baseline had a faster decline rate than those with anti-HBs levels of 10–100 mIU/mL. Primary vaccination may not provide lifelong protection since HBV immunity deteriorates over time. Individuals with higher initial HBV immunity levels may experience a faster decline rate.

Eliminating viral hepatitis in children after liver transplants: How to reach the goal by 2030

Viral hepatitis infections are a great burden in children who have received liver transplant. Hepatotropic viruses can cause liver inflammation that can develop into liver graft fibrosis and cirrhosis over the long term. Immunological reactions due to viral hepatitis infections are associated with or can mimic graft rejection, rendering the condition difficult to manage. Prevention strategies using vaccinations are agreeable to patients, safe, cost-effective and practical. Hence, strategies to eliminate viral hepatitis A and B focus mainly on immunization programmes for children who have received a liver transplant. Although a vaccine has been developed to prevent hepatitis C and E viruses, its use is not licensed worldwide. Consequently, eliminating hepatitis C and E viruses mainly involves early detection in children with suspected cases and effective treatment with antiviral therapy. Good hygiene and sanitation are also important to prevent hepatitis A and E infections. Donor blood products and liver grafts should be screened for hepatitis B, C and E in children who are undergoing liver transplantation. Future research on early detection of viral hepatitis infections should include molecular techniques for detecting hepatitis B and E. Moreover, novel antiviral drugs for eradicating viral hepatitis that are highly effective and safe are needed for children who have undergone liver transplantation.

Long-term Immunity Against Hepatitis B Virus After Routine Immunization Among Adults Visiting Primary Care Centers in Riyadh, Saudi Arabia

Objective

This study aimed to determine the persistence of induced immunity against hepatitis B virus (HBV) among adults routinely vaccinated during their infancy and correlate the level of induced immunity with participant characteristics.

Methodology

This was a cross-sectional study conducted among visitors to primary care centers of the Ministry of Health (MOH) in Riyadh, the Kingdom of Saudi Arabia (KSA) during the period from August 2020 to January 2021. The study population included healthy adults of both genders who had received full doses of the HBV vaccine in infancy. Data related to participant characteristics were collected using a self-administered questionnaire. A blood sample was then taken from each participant to measure the serum level of hepatitis B surface antigen (HBsAg), antibodies against HBsAg (anti-HBs), and antibodies against hepatitis B core antigen (ani-HBc).

Results

A total of 400 subjects participated in the study; the mean age of the cohort was 25 years. Almost all of them were Saudis (99.30%), and more than half (57.50%) were males. Only 24.30% had an anti-HBs antibodies level of ≥10 IU/L, and all respondents were negative for HBs antigen. No significant association between participant characteristics and anti-HBs antibody levels was found.

Conclusion

A decline in immunity many years after HBV vaccinations taken in infancy has been well-documented. However, for low-risk populations, the boosting of HBV vaccines is probably unnecessary since the immune memory provides sufficient protection despite low or undetectable anti-HBs antibodies.

Immune persistence induced by three doses of 60 μg hepatitis B vaccine in non-responders following standard primary vaccination in Chinese adults

This study consisted of two rounds of cross-sectional observations designed to evaluate the persistence of immune protection induced high antigen content hepatitis B (HB) vaccine at 60 μg/1.0 ml formulations administered at a three-dose schedule (Days 0, 28, and 56) in non-responders to routine HB vaccination. In the original phase 3 study, we enrolled 1091 healthy participants (16-60 years old) seronegative for antibody against HB surface antigen (anti-HBs) after primary vaccination. Participants were randomized (2:2:1) to receive three booster doses of HB vaccine containing 60 μg, 30 μg, or 10 μg of antigen per dose 28 days apart. In the group receiving the 60 μg HB vaccine, 428 participants' serum samples were available at pre-vaccination and 28 days after each vaccine dose and were included in immunogenicity analysis. With two written informed consents, we collected blood samples from 276 (67.2%) participants in 2014 and 239 (58.2%) in 2019, who had completed the full course of revaccination and reached the seropositive (anti-HBs≥10 mIU/ml) standard in the 60 μg vaccine group of the original phase 3 study. The HBV seropositive rate was found to decrease from 96.0% in 28 days after receiving the third dose of 60 μg HB vaccine, to 48.2% in 2014, and to 40.6% in 2019, with anti-HBs GMC of seropositive individuals was 584.0 mIU/ml, 142.4 mIU/ml, and 169.1 mIU/ml, respectively. Analysis of 181 vaccinees who had serologic test results available both in 2014 and in 2019, and results revealed a dynamic trend in anti-HBs titer similar to that for the whole immune persistence cohort. Of paramount importance, the serologic test results found that 24.9% (45/181) participants had higher anti-HBs concentrations in 2019 than in 2014, this could be interpreted as natural boosters, secondary to HBV exposure without infection because protected. In conclusion, protective antibody persists about 11 years after immunization of Chinese non-responders with 3 doses of 60 μg HB vaccine. Booster doses of vaccine do not seem necessary to ensure long-term protection.

Levels of hepatitis B antibody titers are affected by age and doses gap time in children from a high endemic area of the western Amazon

Background

Despite completion of the vaccine schedule for hepatitis B virus (HBV), children may display levels of HBV surface antibodies (anti-HBs) that are considered inadequate for sufficient protection (<10 IU/L).

Aims

Our aim was to investigate if age and gap time between HBV vaccine doses may negatively affect the levels of anti-HBs in children, and if these relationships are modified by sex.

Methods

In a high-endemic HBV region of the western Brazilian Amazon we enrolled children who had completed the HBV vaccine schedule. All children underwent analysis of anti-HBs and a clinical examination.

Results

We included 522 children (mean age 4.3 ± 0.8 years; 50% male). Median anti-HBs was 28.4 [interquartile range (IQR) 5.4 to 128.6] IU/L and 32% had anti-HBs <10 IU/L. The median gap time from last to preceding dose was 2.4 [IQR 2.1 to 3.3] months. Levels of anti-HBs decreased with higher age (-42% per year increase [95%CI -56% to -24%], p<0.001), but not with longer gap time (+23% per month increase [95%CI -16% to +62%], p = 0.249). After adjusting for relevant confounders, gap time became significant (p = 0.032) and age remained a significant predictor of anti-HBs (p<0.001).

Conclusion

One third of assessed children displayed anti-HBs <10 IU/L. Levels of anti-HBs decreased with higher age and increased with longer gap time between the last two doses.

Antibody avidity, persistence, and response to antigen recall: comparison of vaccine adjuvants

Differences in innate immune ‘imprinting’ between vaccine adjuvants may mediate dissimilar effects on the quantity/quality of persisting adaptive responses. We compared antibody avidity maturation, antibody/memory B cell/CD4⁺ T cell response durability, and recall responses to non-adjuvanted fractional-dose antigen administered 1-year post-immunization (Day [D]360), between hepatitis B vaccines containing Adjuvant System (AS)01_B, AS01_E, AS03, AS04, or Alum (NCT00805389). Both the antibody and B cell levels ranked similarly (AS01_B/E/AS03 > AS04 > Alum) at peak response, at D360, and following their increases post-antigen recall (D390). Proportions of high-avidity antibodies increased post-dose 2 across all groups and persisted at D360, but avidity maturation appeared to be more strongly promoted by AS vs. Alum. Post-antigen recall, frequencies of subjects with high-avidity antibodies increased only markedly in the AS groups. Among the AS, total antibody responses were lowest for AS04. However, proportions of high-avidity antibodies were similar between groups, suggesting that MPL in AS04 contributes to avidity maturation. Specific combinations of immunoenhancers in the AS, regardless of their individual nature, increase antibody persistence and avidity maturation.

Biosensing strategies for the electrochemical detection of viruses and viral diseases - A review

Viruses are the causing agents for many relevant diseases, including influenza, Ebola, HIV/AIDS, and COVID-19. Its rapid replication and high transmissibility can lead to serious consequences not only to the individual but also to collective health, causing deep economic impacts. In this scenario, diagnosis tools are of significant importance, allowing the rapid, precise, and low-cost testing of a substantial number of individuals. Currently, PCR-based techniques are the gold standard for the diagnosis of viral diseases. Although these allow the diagnosis of different illnesses with high precision, they still present significant drawbacks. Their main disadvantages include long periods for obtaining results and the need for specialized professionals and equipment, requiring the tests to be performed in research centers. In this scenario, biosensors have been presented as promising alternatives for the rapid, precise, low-cost, and on-site diagnosis of viral diseases. This critical review article describes the advancements achieved in the last five years regarding electrochemical biosensors for the diagnosis of viral infections. First, genosensors and aptasensors for the detection of virus and the diagnosis of viral diseases are presented in detail regarding probe immobilization approaches, detection methods (label-free and sandwich), and amplification strategies. Following, immunosensors are highlighted, including many different construction strategies such as label-free, sandwich, competitive, and lateral-flow assays. Then, biosensors for the detection of viral-diseases-related biomarkers are presented and discussed, as well as point of care systems and their advantages when compared to traditional techniques. Last, the difficulties of commercializing electrochemical devices are critically discussed in conjunction with future trends such as lab-on-a-chip and flexible sensors.

Towards the elimination of viral hepatitis in Thailand by the year 2030

Viral hepatitis is a global problem with mortality comparable to HIV, tuberculosis and malaria. The WHO aims to eliminate hepatitis B (HBV) and hepatitis C (HCV) by 2030. Improved socioeconomic status of developing countries such as Thailand has reduced the incidence and morbidity associated with hepatitis A. Since the beginning of hepatitis B vaccination in all Thai newborns in 1992, at least 95% of one-year-olds are currently receiving 3–4 hepatitis B doses. The second vaccination of newborns of carrier mothers at 1 month of age has contributed to an effective reduction in mother-to-child transmission. Universal vaccination, blood donation screening, and decreasing needle sharing have reduced hepatitis B infection. Under the test and treat model, cost-effective screening at the point-of-care (health center or village hospital) is recommended for adults >30 years-old. Following referral to a tertiary healthcare center for a treatment plan in developing disease management plan, its implementation by trained healthcare professionals is preferably administered at the point-of-care. Hepatitis C prevalence is also decreasing as a result of blood-borne pathogen awareness. Current hepatitis C infection is highest for adults >35 years who were born prior to 1983, with screening is recommend once in their lifetime. Treatment strategy recommendation follows that of hepatitis B. The availability of direct antiviral agents with high cure rates is expected to contribute to the reduction in hepatitis C transmission and mortality as set forth by the WHO policy. Thus, ensuring the successful planning of hepatitis elimination in Thailand requires pilot regional assessment prior to national implementation.

Seroconversion of hepatitis B surface antigen among those with previously successful immune response in Southern China

Recommendations promoted worldwide have suggested a period of protection lasting more than 20 years against hepatitis B (HB) following primary immunization. Starting in 1987, universal HB vaccinations were carried out in Long An County, Guangxi Province, one of the earliest counties in which plasma-derived HB vaccine was delivered to newborns across China. Data collection targeted toward understanding the long term (26–33 years since primary immunization) immune effects of the plasma-derived HB vaccine was conducted in 2015; a second data collection was carried out in 2019 to assess seroconversion in the same cohort. This study qualitatively compared positive vs negative results and quantitatively assessed HB biomarkers – HB surface antigen (HBsAg), antibody to HBsAg (anti-HBs), HB e-antigen (HBeAg), antibody to HBeAg (anti-HBe), and antibody to HB core antigen (anti-HBc) – in serum 26–33 years after the full initial course of HB vaccination, then analyzed anti-HBs seroconversion using the two-phase sampling method in the same cohort and calculated the anti-HBs seroconversion rate from 2015 to 2019. The protective sero-conversion rate (anti-HBs ≥10mIU/mL) was 37.6% (192/511); the HBsAg-positive rate was 5.3% (27/511); the anti-HBs mean geometric titer (GMT) was 11.1 mIU/mL. Among the 143 participants involved in both 2015 and 2019 data collections, the seroconversion rate was 3.5% (5/143); two individuals had protective anti-HBs levels in 2015. These findings indicate that anti-HBs status can be seroconverted to a protective concentration level 4 years earlier in a high HBV epidemic region. The role of genomic mutations and the disappearance of immune memory and seroconversion should be investigated.

Kinetics of Anti-Hepatitis B Surface Antigen Titers in Nurse Students after a Two-Year Follow-Up

Infection caused by hepatitis B virus (HBV) can be prevented through a safe and effective vaccine. This study analysed the kinetics of serum antibodies against hepatitis B surface antigen (HBsAg) (anti-HBs) titers in relation to previous vaccine boosters in Italian nursing students who were followed up for two years. Serum anti-HBs titers were evaluated at the first visit, after vaccine booster (if required) and at visit after two years. Overall, 483 students (mean age = 21.7 years; SD = 3.7) with median anti-HBs IgG titer of 6 mUI/mL (interquartile range (IQR) = 0–34) were enrolled. A total of 254 (52.5%) students with a titer lower than 10 mIU/mL were offered an anti-HBV booster at the first visit. Among these students, an exponential relation between anti-HBs IgG titer, one month after HBV booster and anti-HBs IgG titer two years later was found (y = 3.32 exp (0.0045x); R² = 0.48; p < 0.001). Students with anti-HBV titer higher than 10 mIU/mL (N = 229) were followed up, and anti-HBs IgG titers at follow-up visit linearly correlated with anti-HBV baseline titers (y = 0.86x + 26.2; R² = 0.67; p < 0.001). A decrease in anti-HBs titers can be expected a few years after the anti-HBV booster dose. This reduction is more pronounced than that observed in students not administered the booster dose and is exponential with respect to basal titers assessed after the booster dose.

Cross-sectional study of hepatitis B antibody status in health care workers immunized as children at an academic medical center in Wisconsin

Individuals who received the hepatitis B vaccine series as young children are entering the healthcare workforce. Our study measured the persistence of antibody to the hepatitis B surface antigen (anti-HBs) at time of employment. Among 986 individuals born in 1991 or more recently with documentation of completion of the hepatitis B vaccine series, 51% had anti-HBs < 10mIU/ml. Of these 507 healthcare workers, 446 (88%) received documented fourth dose of hepatitis B vaccine followed by another anti-HBs ≥ 28 days post vaccination; 11% (50/446 or 5% of the total population) did not mount an anamnestic response. The non-responders were more likely to be male or complete the vaccine series prior to age 7 months. Measuring anti-HBs at the time of hire in this population of healthcare workers who had documentation of hepatitis B series completion as young children may be unnecessary because of the high rate of hepatitis B vaccine protection.

A Universal Plug-and-Display Vaccine Carrier Based on HBsAg VLP to Maximize Effective Antibody Response

Development of effective malaria vaccines requires delivery platforms to enhance the immunogenicity and efficacy of the target antigens. This is particularly challenging for transmission-blocking malaria vaccines (TBVs), and specifically for those based on the Pfs25 antigen, that need to elicit very high antibody titers to stop the parasite development in the mosquito host and its transmission. Presenting antigens to the immune system on virus-like particles (VLPs) is an efficient way to improve the quantity and quality of the immune response generated. Here we introduce for the first time a new VLP vaccine platform, based on the well-established hepatitis B surface antigen (HBsAg) fused to the SpyCatcher protein, so that the antigen of interest, linked to the SpyTag peptide, can be easily displayed on it (Plug-and-Display technology). As little as 10% of the SpyCatcher::HBsAg VLPs decorated with Pfs25::SpyTag (molar ratio) induces a higher antibody response and transmission-reducing activity in mice compared to the soluble protein, with 50 and 90% of the VLP coupled to the antigen further enhancing the response. Importantly, using this carrier that is a vaccine antigen itself could be beneficial, as we show that anti-HBsAg IgG antibodies are induced without interfering with the Pfs25-specific immune response generated. Furthermore, pre-existing anti-HBsAg immunity does not affect the antigen-specific response to Pfs25::SpyTag-SpyCatcher::HBsAg, suggesting that these VLPs can have a broad use as a vaccine platform.

Persistence of HBsAg-specific antibodies and immune memory two to three decades after hepatitis B vaccination in adults

The duration of protection after hepatitis B vaccination is not exactly known. This phase IV study evaluated antibody persistence and immune memory 20-30 years after adult immunization with recombinant hepatitis B vaccine (HBsAg vaccine, Engerix-B) in routine clinical practice. Men and women 40-60 years old, with documented evidence of vaccination with three or four HBsAg vaccine doses 20-30 years earlier and without subsequent booster, were enrolled and received HBsAg vaccine as challenge dose. HBsAg-specific antibodies (anti-HBs) and frequencies of HBsAg-specific circulating memory B cells and CD4⁺ T cells expressing combinations of activation markers (CD40L, IL2, IFNγ, TNFα) were measured prechallenge, 7 and 30 days postchallenge. Of 101 participants in the according-to-protocol cohort for immunogenicity, 90.1% had anti-HBs concentrations ≥ 10 mIU/mL prechallenge administration; 84.2% and 100% mounted an anamnestic response 7 and 30 days postchallenge, respectively. HBsAg-specific memory B and CD4⁺ T cells expressing at least two activation markers were low prechallenge and increased markedly postchallenge. These results suggest sustained immune memory and long-term protection 20-30 years after a complete primary HBsAg vaccination course during adulthood, in line with current recommendations that a booster is not needed in fully vaccinated immunocompetent adults.

Serological evidence of hepatitis A, B, and C virus infection in older adults in Khon Kaen, Thailand and the estimated rates of chronic hepatitis B and C virus infection in Thais, 2017

Hepatitis A (HAV), hepatitis B (HBV), and hepatitis C (HCV) viruses are hepatotropic viruses responsible for acute/chronic hepatitis associated with liver failure, cirrhosis, and hepatocellular carcinoma. Due to the limited data on the prevalence of hepatitis in the older population in Thailand, this study aimed to evaluate the seroprevalence of these viruses in elderly Thais. Using an automated immunoassay, serum samples from individuals older than 60 years of age in Chum Phae district of Khon Kaen province in northeast Thailand were analyzed for anti-HAV (n = 93), HBV markers (n = 460, HBsAg, anti-HBs, and anti-HBc), and anti-HCV (n = 460). Samples were classified into five age groups (61-65, 66-70, 71-75, 76-80, and >80 years). The overall seroprevalence of anti-HAV, HBsAg, anti-HBc, anti-HBs, and anti-HCV was 98.9%, 4.6%, 51.5%, 32.4%, and 1.3%, respectively. When samples were stratified into three groups representing three generations (children/young adults aged 6 months-30 years and middle-aged adults between 31-60 years old from a previous survey, and older adults aged >60 years from the current study), the highest levels of anti-HAV and anti-HBc were found in older adults. Children/young adults had the lowest levels of HBsAg and anti-HCV, and the highest level of anti-HBs. These findings are consistent with the integration of HBV vaccination into the Expanded Program on Immunization (EPI) in 1992 and coincide with increased awareness of blood-borne viral transmission in Thailand. Extrapolating from our data, the estimated numbers of cases of chronic HBV and HCV infection in Thailand in 2017 were 2.2 and 0.79 million, respectively. Thus, effective treatments for viral hepatitis B and C for middle-aged and elderly Thais are needed. This seroprevalence survey could be used to help formulate policies and possible guidelines for treatment and prevention in specific age groups, which is recommended to facilitate the elimination of viral hepatitis by 2030.

Immune persistence 17 to 20 years after primary vaccination with recombination hepatitis B vaccine (CHO) and the effect of booster dose vaccination

BACKGROUND

To assess the immune persistence conferred by a Chinese hamster ovary (CHO)-derived hepatitis B vaccine (HepB) 17 to 20 years after primary immunization during early life.

METHODS

Participants born between 1997 and 1999 who received a full course of primary vaccination with HepB (CHO) and who had no experience with booster vaccination were enrolled. Blood samples were required from each participant for measurement of hepatitis B surface antibody (anti-HBs), surface antigen and core antibody levels. For those who possessed an anti-HBs antibody < 10 mIU/mL, a single dose of HepB was administered, and 30 days later, serum specimens were collected to assess the booster effects.

RESULTS

A total of 1352 participants were included in this study. Of these, 1007 (74.5%) participants could retain an anti-HBs antibody ≥10 mIU/mL, with a geometric mean concentration (GMC) of 57.4 mIU/mL. HBsAg was detected in six participants, resulting in a HBsAg carrier rate of 0.4% (6/1352). Of those participants with anti-HBs antibodies < 10 mIU/mL, after a challenge dose, 231 (93.1%) presented an anti-HBs antibody ≥10 mIU/mL, with a GMC of 368.7 mIU/mL. A significant increase in the anti-HBs positive rate (≥ 10 mIU/mL) after challenge was observed in participants with anti-HBs antibodies between 2.5 and 10 mIU/mL and participants boosted with HepB (CHO), rather than those with anti-HBs antibodies < 2.5 mIU/mL and those boosted with HepB (SC).

CONCLUSION

Since satisfactory immune protection against HBV infection conferred by primary vaccination administered 17-20 years ago was demonstrated, there is currently no urgent need for booster immunization.

Asymptomatic hepatitis B carriers who were vaccinated at birth

The long-term persistence of immunity following universal infant immunization against hepatitis B virus (HBV) and the need for a subsequent booster dose in adolescence remain under debate. With data derived from Long'an County, Guangxi, China, we reported previously that the prevalence of hepatitis B surface antigen (HBsAg) among adults born from 1987 to 1993 increases with age, although these individuals had received a first dose of the vaccine within 24 hours of birth. Here, we sought the source of transmission by comparison of genotypes among their family members using phylogenetic analysis of complete HBV S gene sequences. For comparison, we screened 2199 vaccinated individuals aged 5 to 17 in Cang Wu County and 1592 vaccinated individuals aged 3 to 7 in Ling Shan County in Guangxi for HBsAg carriers and investigate their family members. In total, 50 asymptomatic HBsAg carriers who were vaccinated at birth and 152 family members were analyzed. The results showed that 25% (95% CI: 6.0-44.0) of the HBsAg-positive children had not acquired their HBV infection from their mothers. This phenomenon showed a trend that increases with age. Antibody escape mutations were detected in 22.9% (95% CI: 11.0-34.8) of the isolates. In conclusion, a booster dose may be necessary for adolescence who were vaccinated at birth in highly endemic countries.

TBA225, a fusion toxoid vaccine for protection and broad neutralization of staphylococcal superantigens

Superantigens (SAgs) play a major role in the pathogenesis of Staphylococcus aureus and are associated with several diseases, including food poisoning, bacterial arthritis, and toxic shock syndrome. Monoclonal antibodies to these SAgs, primarily TSST-1, SEB and SEA have been shown to provide protection in animal studies and to reduce clinical severity in bacteremic patients. Here we quantify the pre-existing antibodies against SAgs in many human plasma and IVIG samples and demonstrate that in a major portion of the population these antibody titers are suboptimal and IVIG therapy only incrementally elevates the anti-SAg titers. Our in vitro neutralization studies show that a combination of antibodies against SEA, SEB,and TSST-1 can provide broad neutralization of staphylococcal SAgs. We report a single fusion protein (TBA₂₂₅) consisting of the toxoid versions of TSST-1, SEB and SEA and demonstrate its immunogenicity and protective efficacy in a mouse model of toxic shock. Antibodies raised against this fusion vaccine provide broad neutralization of purified SAgs and culture supernatants of multiple clinically relevant S. aureus strains. Our data strongly supports the use of this fusion protein as a component of an anti-virulence based multivalent toxoid vaccine against S. aureus disease.

Antibody persistence in pre-school children after hexavalent vaccine infant primary and booster administration

Objective: Antibody persistence evaluation for all antigens of a fully liquid DTaP-IPV-HB-PRP~T vaccine at 3.5 and 4.5 y of age following different primary series and booster schedules in South Africa and Latin America.

Methods: Participants had completed one of two previous studies (Study 1-South Africa; Study 2-Latin America). In Study 1, participants who had not received HB vaccine at birth received a 6–10-14 week primary series of DTaP-IPV-HB-PRP~T or DTwP/PRP~T-Hib+HB+OPV and a third group who had received HB vaccine at birth received a 6–10-14 week primary series of DTaP-IPV-HB-PRP~T; all received a booster (15–18 months) of the primary series vaccine(s) except for HB in the DTwP/PRP~T-Hib group. In Study 2, participants received HB vaccine at birth, a 2–4-6 month primary series of DTaP-IPV-HB-PRP~T or DTaP-HB-IPV//PRP~T, and a DTaP-IPV-HB-PRP~T or DTaP-HB-IPV//PRP~T booster (12–24 months). Participants were followed up at 3.5 and 4.5 y of age for antibody persistence.

Results: Approximately 80% of eligible participants were assessed. In Study 1, a birth dose of HB increased anti-HBs persistence (≥10 mIU/mL) following DTaP-IPV-HB-PRP~T primary and booster vaccination from 76.3% to 96.1% at 3.5 y of age and from 73.3% to 96.1% at 4.5 y of age; in Study 2, anti-HBs persistence was high and similar in each group. For the other antigens, there were no differences between groups or studies at 3.5 or 4.5 y.

Conclusion: Good persistence of antibodies to each antigen in the DTaP-IPV-HB-PRP~T vaccine up to pre-school age, irrespective of the vaccination schedule during the first 2 y of life.

Trends in Incidence of Two Major Subtypes of Liver and Bile Duct Cancer: Hepatocellular Carcinoma and Cholangiocarcinoma in Songkhla, Southern Thailand, 1989-2030

Background

The incidence of liver and bile duct cancer continues to rise, especially in Thailand. We aimed to project the trends in incidence of this rare but lethal cancer in southern Thailand in order to determine its future disease burden.

Methods

Gender-specific trends in age-standardized incidence rates per 100,000 person-years for hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) cases in Songkhla province of southern Thailand diagnosed between 1989 and 2013 were estimated and projected up to year 2030 using three different modeling techniques: a joinpoint model, an age-period-cohort model, and a modified age-period-cohort model.

Results

Of 2,676 liver and bile duct (LBD) cancer cases identified, 73% were males, 51% were aged between 50 and 69 years, and HCC (44.4%) was slightly more common than CCA (38.1%). The models all predicted an increase in the incidence rate of CCA up to 2025 for both sexes whereas the incidence of HCC is expected to decrease among males and stabilize among females. The incidence rates of HCC and CCA among males in 2030 could reach 6.7 and 9.4 per 100,000 person-years, respectively, whereas the expected rates of HCC and CCA among females are expected to be around 1.5 and 3.9 per 100,000 person-years, respectively.

Conclusions

The incidence of cholangiocarcinoma is expected to increase in Songkhla and will contribute a larger proportion of LBD cancers in the future. Future public health efforts and research studies should focus on this increasing trend.

Long-term antibody persistence against hepatitis B in adolescents 14-15-years of age vaccinated with 4 doses of hexavalent DTPa-HBV-IPV/Hib vaccine in infancy

We evaluated antibody persistence against hepatitis B virus (HBV) in adolescents previously vaccinated with a hexavalent diphtheria-tetanus-acellular pertussis-HBV-inactivated poliovirus-Haemophilus influenzae type b conjugate vaccine (DTPa-HBV-IPV/Hib), as part of the national newborn immunization program in Germany. We also assessed the anamnestic response to a challenge dose of a monovalent HBV vaccine. In this phase 4, open-label, non-randomized study (NCT02798952), 302 adolescents aged 14-15 years, primed in their first 2 years of life with 4 DTPa-HBV-IPV/Hib doses, received one challenge dose of monovalent HBV vaccine. Blood samples were taken before and one month post-vaccination and used to determine antibody levels against hepatitis B surface antigen (HBs). Reactogenicity and safety were also assessed post-challenge dose. Pre-challenge dose, 53.7% of 268 participants included in the according-to-protocol cohort for immunogenicity had anti-HBs antibody concentrations ≥10 mIU/mL (seroprotection cut-off) and 16.8% had anti-HBs antibody concentrations ≥100 mIU/mL. One month post-challenge dose, 93.3% of adolescents had anti-HBs antibody concentrations ≥10 mIU/mL and 87.3% had antibody concentrations ≥100 mIU/mL. An anamnestic response was mounted in 92.5% of adolescents. Injection site pain (in 33.6% of participants) and fatigue (30.2%) were the most frequently reported solicited local and general symptoms, respectively. Six of the 55 unsolicited adverse events reported were considered vaccination-related. Two vaccination-unrelated serious adverse events were reported during the study. Long-term antibody persistence against hepatitis B was observed in 14-15 years old adolescents previously primed in infancy with DTPa-HBV-IPV/Hib. A challenge dose of monovalent HBV vaccine induced strong anamnestic response, with no safety concerns.

Implementation of hepatitis B vaccine in high-risk young adults with waning immunity

Universal hepatitis B (HB) vaccination among Thai newborns was initiated in 1992. The first dose of the monovalent HB vaccine was given at birth, then at months 2 and 6 simultaneously with the diphtheria-tetanus-pertussis whole-cell (DTPw) vaccine. In 2008, Thailand replaced the monovalent HB vaccine at months 2 and 6 with a combined DTP-HB given at months 2, 4, and 6, with an added monovalent HB vaccine at month 1 for infants whose mothers were HBV carriers. Despite this rigorous HB vaccination schedule, vaccinated infants who are now adolescents do not possess a protective level of anti-HB surface antigen (anti-HBs) (≥10 mIU/ml). Thus, many young adults may be rendered susceptible to HB infection. Our objective was to determine how HB booster vaccination may benefit high-risk adolescents. We evaluated the serological records of a cohort of medical students (n = 291), which showed that 271 students (93.1%) possessed anti-HBs less than the accepted protective level (<10 mIU/ml) and subsequently received the HB vaccine booster prior to medical school enrollment. We then examined the anti-HB surface antibody (anti-HBs) in 216 individuals six weeks after they were immunized. We found that 61%, 88%, and 94% of individuals with pre-booster anti-HBs of <1 mIU/ml, 1-<3 mIU/ml, and 3-<10 mIU/ml achieved protective anti-HBs, respectively. Post-booster geometric mean titers were 305, 513, and 1,929 mIU/ml in these groups and correlated with pre-booster anti-HBs titers. These data suggest that medical students with known anti-HBs <1 mIU/ml will benefit from 3 doses of HB vaccine at 0, 1, and 6 months. Students with anti-HBs 1-<10 mIU/ml would benefit from an HB vaccine booster without further anti-HBs evaluation.

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.

Persistence of immune memory among adults with normal and high antibody response to primary hepatitis B vaccination: Results from a five-year follow-up study in China

Immune memory after hepatitis B vaccination among adults is still under investigation. In this study, adults who had normal and high antibody response to the primary series of hepatitis B vaccination (HepB) were followed up at 5 years after the primary immunization. A booster dose was given to those who had low hepatitis B surface antibody (anti-HBs) titers, defined as anti-HBs levels < 10 mIU/mL. Blood samples were collected at two weeks after the booster and anti-HBs levels were measured. We assumed those with ant-HBs levels > = 10 mIU/mL after the booster had anamnestic response. In total, 242 persons completed the booster and the anti-HBs test. The anamnestic response rate was 99.59% (241/242) and geometric mean concentration (GMC) of anti-HBs after the booster was 2989 mIU/mL (95% CI: 255, 35085). Anti-HBs titer after the booster dose had a positive correlation with anti-HBs titers measured right after the primary immunization as well as anti-HBs titers 5 years later just before the booster. After the booster, no significant difference was found in anti-HBs titers between participants who were immunized with the 10μg HepB vaccine and those with the 20μg vaccine. Multivariable analysis showed that 1) vaccine brand used for the primary vaccination, 2) anti-HBs titers after primary vaccination and 3) anti-HBs titers before the booster dose were independently associated with the anti-HBs titers after the booster 1) β = -0.21, 95% CI: -0.33, -0.09, P = 0.001; 2) β = 0.07, 95% CI: 0.05, 0.09, P < 0.001; 3) β = 0.04, 95% CI: 0.02, 0.07, P < 0.001). In summary, anamnestic response exists among almost all adults at five years after HepB primary immunization. Vaccine brand used for primary vaccination, initial anti-HBs titers after primary immunization and anti-HBs titers before the booster were the independent predictive factors of HepB anamnestic response titers.

Persistence of hepatitis B immune memory until 9-10 years of age following hepatitis B vaccination at birth and DTaP-IPV-HB-PRP∼T vaccination at 2, 4 and 6 months

OBJECTIVE

To evaluate the long-term persistence of anti-hepatitis B surface (HBs) antibodies and the response to a HB challenge re-vaccination in children who had received a primary series of DTaP-IPV-HB-PRP∼T (Hexaxim™) or DTaP-IPV-HB/PRP∼T (Infanrix hexa™).

METHODS

Two cohorts of participants who had previously received HB vaccine at birth followed by either DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T co-administered with PCV7 at 2, 4, 6 months of age in a randomized, Phase III, observer-blind study in Thailand, were followed up for anti-HBs antibodies (geometric mean concentrations [GMCs] and seroprotection [SP] rate [% of participants with a titer ≥10 mIU/mL]) at 12-18 months of age and 9-10 years of age. A monovalent HB challenge re-vaccination was administered at 9-10 years of age and the anamnestic response was evaluated.

RESULTS

Anti-HBs GMCs and SP rates in the DTaP-IPV-HB-PRP∼T and DTaP-IPV-HB/PRP∼T groups were high and similar post-primary vaccination series (2477 mIU/mL and 99.5% and 2442 mIU/mL and 99.5%, respectively) and declined to a similar extent in each group at 12-18 months (154.5 mIU/mL and 90.8% and 162.3 mIU/mL and 96.5%, respectively). Antibody levels further declined at 9-10 years of age (13.3 mIU/mL and 49.3% and 8.0 mIU/mL and 42.9%) and a strong anamnestic response occurred in each group post-HB challenge re-vaccination (92.8% and 98.7%, respectively).

CONCLUSION

The kinetics of long-term anti-HBs antibody persistence were similar following a primary series of DTaP-IPV-HB-PRP∼T or DTaP-IPV-HB/PRP∼T. The response to a subsequent HB challenge re-vaccination was strong and similar in each group, demonstrating persisting immune memory.

The effects of booster vaccination of hepatitis B vaccine on children 5-15 years after primary immunization: A 5-year follow-up study

The aim of this study was to evaluate changes in hepatitis B surface antibody titers (anti-HBs) after booster vaccinations in children aged 5-15 y and to provide suitable immunization strategies. A total of 2208 children were initially enrolled in screening, and 559 children were finally included. The participants were divided into 2 groups according to their pre-booster anti-HBs levels: Group I, <10 mIU/ml and Group II, ≥10 mIU/ml. Group I was administered 3 doses of booster hepatitis B vaccine (0-1-6 months, 10 μg), and Group II was administered 1 dose of booster hepatitis B vaccine (10 μg). The antibody titer changes were examined at 4 time points: 1 month after dose 1 and dose 3, and 1 year and 5 years after dose 3. The protective seroconversion rates at those points were 95.65%, 99.67%, 97.59% and 91.05% (p < 0.001), respectively, in Group I, and 100.00%, 99.87%, 99.66% and 98.21% (χ² = 6.04, p = 0.11), respectively, in Group II. The GMT in subjects aged 5-9 y were higher than that in subjects aged 10-15 y in both Group I and Group II at 1 month after dose 1, but no difference was observed at the other three time points. This study demonstrates that booster vaccination has a good medium-term effect. A booster dose for subjects with protective antibodies is not necessary but effective, and 3 doses of hepatitis B vaccination are recommended for those who have lost immunological memory. Receiving booster immunization at the age of 10-15 years may be more appropriate for individuals living in HBV high epidemic areas.

Vaccinations for the HIV-Infected Adult: A Review of the Current Recommendations, Part I

Vaccination is a critical component for ensuring the health of those living with the human immunodeficiency virus (HIV) by protection against vaccine-preventable diseases. Since HIV-infected persons may have reduced immune responses and shorter durations of protection post-vaccination, HIV-specific guidelines have been published by global and national advisory organizations to address these potential concerns. This article provides a comprehensive review of the current guidelines and evidence-based data for vaccinating HIV-infected adults, including guidance on modified vaccine dosing and testing strategies, as well as safety considerations, to enhance protection among this vulnerable population. In the current article, part I of the two-part series, inactivated vaccines with broad indications as well as vaccines for specific risk and age groups will be discussed.

Changes in hepatitis B virus antibody titers over time among children: a single center study from 2012 to 2015 in an urban of South Korea

Background

Hepatitis B virus (HBV) infection is the most common cause of liver disease in endemic areas such as South Korea. After HBV vaccination, hepatitis B surface antibody (HBsAb) titers gradually decrease. Trends in HBsAb titers have not been evaluated among children in South Korea over the past decade.

Methods

We screened 6155 patients (aged 7 months to 17 years) who underwent HBV antigen/antibody testing at Chung-Ang University Hospital from May 2012 to April 2015. Titer criteria were defined as follows: positive, titer ≥100 IU/L; weakly positive, titer 10–99 IU/L; and negative, titer <10 IU/L. We also compared titers before and 1 month after a single booster vaccination.

Results

Of the 5655 patients included, 3016 were male and 5 (0.09%) tested positive for HBV surface antigen. A marked reduction in antibody titer was observed until 4 years of age. Thereafter, the titers showed fluctuating decreases. HBsAb titers reached their lowest levels by 14 years of age. After 7 years of age, 50% of patients tested negative for HBsAb. Simple linear analysis showed that the titer reached levels of <10 IU/L and zero at 12.9 and 13.4 years of age, respectively. 1 month after a single booster vaccination was administered to those who were HBsAb-negative (n = 72), 69 children (96%) had developed antibodies while 3 (4%) remained HBsAb-negative.

Conclusions

In conclusion, the continuous reduction in HBsAb titers over time and in each age group was confirmed. The titer level was shown significant decline until age 4. More than half of the sample had negative titers after age 7 years. After booster vaccination, most of child significantly increase titer level.

Safety and immune response to a challenge dose of hepatitis B vaccine in healthy children primed 10years earlier with hexavalent vaccines in a 3, 5, 11-month schedule: An open-label, controlled, multicentre trial in Italy

BACKGROUND AND AIMS

The strategy of vaccinating infants to prevent hepatitis B virus infection in adolescence or adulthood requires durable immunity. This study investigated responses to a challenge dose of monovalent hepatitis B vaccine in children primed with three doses of either Hexavac® or Infanrix hexa® 10years earlier during infancy.

METHODS

This open-label, controlled, multicentre study conducted in Italy, enrolled 751 healthy pre-adolescents (aged 11-13years) who were given either Hexavac (n=409) or Infanrix hexa (n=342) at 3, 5 and 11months of life. All participants received a challenge dose of a monovalent hepatitis B vaccine (HBVaxPro® 5µg). The concentrations of antibodies to hepatitis B surface antigen (anti-HBs) were measured before and 1month after the challenge dose. The analysis was descriptive and no formal hypothesis was tested.

RESULTS

One month post-challenge, 331 participants in the Hexavac cohort [83.6%, 95% CI: 79.6; 87.1] and 324 in the Infanrix hexa cohort [96.4%, 95% CI: 93.8; 98.1] had anti-HBs concentrations ≥10mIU/mL. Before the challenge dose, an anti-HBs concentration of ≥10mIU/mL was found in 94 children in the Hexavac cohort [23.9%, 95% CI: 19.7; 28.4] and in 232 children in the Infanrix hexa cohort [69%, 95% CI: 63.8; 74.0]. Among children with a pre-challenge anti-HBs concentration of <10mIU/mL, 236 [78.7%, 95% CI: 73.6; 83.2] in the Hexavac cohort and 92 [88.5%, 95% CI: 80.7; 93.9] in the Infanrix hexa cohort achieved protective anti-HBs antibody concentrations. No evidence of active hepatitis B disease was observed in either group, and the HBVaxPro challenge dose was well tolerated.

CONCLUSIONS

These data confirm that immune memory persists in a high percentage of children (>80%) at least 10years after a two-dose primary and booster vaccination schedule with a hexavalent vaccine (Hexavac or Infanrix hexa).

TRIAL REGISTRATION

EudraCT Number: 2013-001602-28; clinicaltrials.gov: NCT02012998.

Hepatitis B vaccination status in an at-risk adult population: long-term immunity but insufficient coverage

In France, hepatitis B (HB) vaccine has been offered to all infants since 1994, and was proposed to all children aged 11 years from 1994 to 1998. Nevertheless, HB vaccine hesitancy may result in low vaccination coverage in present-day at-risk adults. We aimed to determine HB vaccination coverage in adults attending a free testing center for sexually transmitted infections (STI). As part of routine care, three classes of data were anonymously collected from attendees over a 3-month period: results of HB serologic tests; date and number of past anti-hepatitis B virus (HBV) immunization(s) (if any) according to health records; and the risk of STI and blood-transmitted infections (BTI). The study included 735 participants (age 27.9 ± 9.2; 59.9% men). According to available health records (341 participants), 56.6% had received at least three and 67.2% at least one vaccine injection(s); 57.7% had received their last injection between 1994 and 1998, reflecting the strong vaccine policy during these years. Serologic testing (in 705 participants) showed evidence of a past or active HBV infection for 33 participants; of the remaining patients, 55.3% had anti-HBs antibody titers ≥10 IU/L. This rate was not higher in participants considered at risk for STI/BTI. Of the participants who received their last vaccine injection more than 15 years previously, 90.5% had anti-HBs antibody concentrations ≥10 and 60.3% ≥100 IU/mL. HB vaccination coverage is low in this population. Most of the vaccinated participants were immunized between 1994 and 1998, suggesting a failure of catch-up immunization of adolescents and at-risk adults. Long-term seroprotection persisted among vaccinated participants.

Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine

Vaccination is the most effective and well-tolerated method of conferring long-term protection against hepatitis A and B viruses (HAV; HBV). Long-term studies are required to characterize the duration of protection and need for boosters. Following primary immunization of 150 and 157 healthy adults with 3-doses of combined hepatitis A/hepatitis B vaccine (HAB; Twinrix™, GSK Vaccines, Belgium) at 0-1-6 months in 2 separate studies, we measured vaccine-induced antibody persistence against HAV and HBV annually for 20 y (Study A: NCT01000324; Study B: NCT01037114). Subjects with circulating anti-HAV antibodies < 15 mIU/mL or with anti-hepatitis B surface antigen < 10 mIU/mL were offered an additional monovalent hepatitis A and/or B vaccine dose (Havrix™/Engerix™-B, GSK Vaccines, Belgium). Applying the immunogenicity results from these studies, mathematical modeling predicted long-term persistence. After 20 y, 18 and 25 subjects in studies A and B, respectively, comprised the long-term according-to-protocol cohort for immunogenicity; 100% and 96.0% retained anti-HAV antibodies ≥ 15 mIU/mL, respectively; 94.4% and 92.0% had anti-HBs antibodies ≥ 10 mIU/mL, respectively. Between Years 16–20, 4 subjects who received a challenge dose of monovalent hepatitis A vaccine (N = 2) or hepatitis B vaccine (N = 2), all mounted a strong anamnestic response suggestive of immune memory despite low antibody levels. Mathematical modeling predicts that 40 y after vaccination ≥ 97% vaccinees will maintain anti-HAV ≥ 15 mIU/mL and ≥ 50% vaccinees will retain anti-HBs ≥ 10 mIU/mL. Immunogenicity data confirm that primary immunization with 3-doses of HAB induces persisting anti-HAV and anti-HBs specific antibodies in most adults for up to 20 y; mathematical modeling predicts even longer-term protection.

Persistence of immunity 18-19 years after vaccination against hepatitis B in 2 cohorts of vaccinees primed as infants or as adolescents in Italy

This study was aimed at assessing the anti-HBs persistence and immune memory 18-19 y after vaccination against hepatitis B in healthy individuals primed as infants or adolescents. We enrolled 405 teenagers (Group A) vaccinated as infants, and 409 young adults (Group B) vaccinated as adolescents. All vaccinees were tested for anti-HBs and anti-HBc antibodies; those found anti-HBc positive were further tested for HBsAg and HBV DNA. Eight individuals belonging to Group B were positive for anti-HBc alone, and were excluded from analysis. Individuals with anti-HBs concentration ≥ 10 mIU/ml were considered protected while those with anti-HBs concentration <10 mIU/ml were offered a booster dose and re-tested 2 weeks later. Overall, 67.9% individuals showed anti-HBs concentrations ≥ 10 mIU/ml (48.9% in Group A vs 87.0% in Group B, p < 0.001). The antibody geometric mean concentration (GMC) was higher in Group B than in Group A (102.5 mIU/ml vs 6.9 mIU/ml; p < 0.001). When boosted, 94.2% of vaccinees with anti-HBs <10 mIU/ml belonging to Group A and 94.7% to Group B showed an anamnestic response. Post-booster GMCs were similar in both groups (477.9 mIU/ml for Group A vs 710.0 mIU/ml for Group B, p = n.s.). Strong immunological memory persists for at least 18-19 y after immunization of infants or adolescents with a primary course of vaccination. Thus, booster doses are not needed at this time, but additional follow up is required to assess the long-life longevity of protection.

Long-term persistence in protection and response to a hepatitis B vaccine booster among adolescents immunized in infancy in the western region of China

OBJECTIVES

To evaluate the persistence of protection from hepatitis B (HB) vaccination among adolescents immunized with a primary series of HB vaccine as infants, and the immune response to booster doses.

METHODS

Healthy adolescents aged 15-17 y vaccinated with HB vaccine only at birth were enrolled. Baseline serum hepatitis B surface antigen (HBsAg), antibody against hepatitis B surface antigen (anti-HBs) and antibody against hepatitis B core antigen (anti-HBc) were detected by Enzyme-Linked Immunosorbent Assay (ELISA) and anti-HBs level was measured using Chemiluminescent Microparticle Immunoassay (CMIA). The rate of HBV infection was calculated. The seroprotection rate of anti-HBs (≥ 10 mIU/ml) and GMC level were used to evaluate the persistence of immunity from HB vaccination. Those with anti-HBs < 10 mIU/ml were immunized with booster doses of HB vaccine and the anamnestic response was assessed.

RESULTS

Of 180 adolescents who received a primary series of HB vaccinations as infants, 3 (1.7%) had HBV infection and 74 (41.1%) had anti-HBs ≥ 10 mIU/ml with a GMC of 145.11 mIU/ml. The remaining 103 (57.2%) with anti-HBs < 10 mIU/ml received a booster dose of 20 μg HB vaccine and achieved the seroprotection rate of 84% (84/100) and a GMC of 875.19 mIU/ml at one month post-booster. An additional dose of 60 μg HB vaccine was administered to the 16 adolescents with anti-HBs < 10 mIU/ml after the first booster. All of them obtained anti-HBs seroprotection with a GMC of 271.02 mIU/ml at 1.5 months after an additional dose.

CONCLUSIONS

Vaccine-induced immunity persisted for up to 15-17 y in 89.3% (158/177) of participants after a primary HB vaccination in infancy. Administering a booster dose of 20μg HB vaccine elicited an anamnestic immune responses in the majority of individuals with baseline anti-HBs <10 mIU/ml.

Lasting immune memory against hepatitis B in 12-13-year-old adolescents previously vaccinated with 4 doses of hexavalent DTPa-HBV-IPV/Hib vaccine in infancy

BACKGROUND

Vaccinating infants against hepatitis B virus (HBV) is the most effective way of preventing the disease. However, since HBV exposure can increase during adolescence, it is essential that antibody persistence is maintained. We evaluated the antibody persistence and immune memory against hepatitis B, in 12-13 y olds who had received complete primary + booster vaccination with diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated poliovirus/Haemophilus influenza type b (DTPa-HBV-IPV/Hib) vaccine in infancy.

METHODS

Open phase-IV study conducted at 12 centers in Germany [NCT02052661]. Adolescents aged 12-13 y, vaccinated with 4 doses of DTPa-HBV-IPV/Hib (Infanrix hexa™, GSK Vaccines) in infancy, received a single challenge dose of monovalent pediatric hepatitis B vaccine (Engerix™-B Kinder; GSK Vaccines). Blood samples were taken before and 1-month post-challenge to measure anti-hepatitis B (anti-HBs) antibodies using a chemiluminescence immunoassay (seroprotection cut-off: ≥10 mIU/ml). Post-challenge adverse events (AEs) were monitored.

RESULTS

300 subjects were vaccinated; of 293 subjects in the ATP immunogenicity cohort, 60.5% had pre-challenge anti-HBs antibodies ≥10 mIU/ml, which rose to 97.6% post-challenge (≥100 mIU/ml in 94.1%). An anamnestic response was seen in 96.5% subjects. A 150-fold increase in antibody geometric mean concentrations was observed (22.4 to 3502.6 mIU/ml). Pain (44%) and fatigue (24.3%) were the most frequent solicited local and general AEs, respectively; 14.7% subjects reported unsolicited symptoms during the 31-day post-vaccination period. Two vaccine-unrelated serious AEs occurred.

CONCLUSION

Vaccination with DTPa-HBV-IPV/Hib in infancy induces sustained seroprotection and immune memory against HBV, as shown by the strong anamnestic response to the hepatitis B vaccine challenge in 12-13 year-old adolescents.

Immunity to hepatitis A and B persists for at least 15 years after immunisation of adolescents with a combined hepatitis A and B vaccine

BACKGROUND

The exact duration of antibody persistence to hepatitis A and B and the need for booster dosing following primary immunisation remains undefined. A long-term study was designed to follow antibody persistence and immune memory on an annual basis for up to 15 years following vaccination during adolescence.

METHODS

Subjects received a combined hepatitis A and B vaccine (Twinrix™, GSK Vaccines, Belgium) at 12-15 years of age, either as 2-dose of the adult formulation or 3-dose of the paediatric formulation. Blood samples were taken every year thereafter to assess antibody persistence and immune memory to hepatitis A and B. Antibodies to hepatitis A virus (anti-HAV) and hepatitis B surface antigen (anti-HBs) were measured at Years 11-15. At Year 15 immune memory was further assessed by measuring the anamnestic response to a challenge dose of the monovalent vaccine, which was administered to subjects whose antibody concentrations fell below the pre-defined cut-offs (anti-HAV: <15mIU/mL; anti-HBs: <10mIU/mL).

RESULTS

209 subjects returned for follow-up at Year 15 of whom 162 were included in the long-term according-to-protocol immunogenicity cohort. All subjects remained seropositive for anti-HAV antibodies, while 81.1% and 81.8% still had anti-HBs antibodies ≥10mIU/mL in the 2- and 3-dose groups, respectively. Following hepatitis B vaccine challenge dose administration to 19 subjects, all except one in the 3-dose group, mounted a robust anamnestic response. The safety and reactogenicity profile of the hepatitis B challenge was consistent with previous experience.

CONCLUSION

Immunity to hepatitis A and B persists 15 years after adolescent vaccination with a combined hepatitis A and B vaccine. Highly effective anamnestic response indicates that a booster dose should not be required for 15 years after primary vaccination.

TRIAL REGISTRATION

http://www.clinicaltrials.govNCT00875485.

Immunity to hepatitis B persists in adolescents 15-16 years of age vaccinated in infancy with three doses of hepatitis B vaccine

OBJECTIVE

Vaccination of infants against hepatitis B virus (HBV) using hepatitis B vaccine is effective in preventing the infection during early childhood and there is a growing evidence of long-term protection. So far, no need for a booster dose has been identified in healthy subjects; however further follow-up continues to determine the exact duration of protection. We evaluated antibody persistence and immune response to a hepatitis B vaccine challenge dose in children aged 15-16 years, previously vaccinated with 3-doses of the same vaccine in infancy (third dose received before 18 months of age).

METHODS

A single hepatitis B vaccine challenge dose containing 10μg hepatitis B surface (HBs) antigen was administered to adolescents aged 15-16 years. Blood samples were taken before and one month after the challenge dose to measure anti-HBs antibodies using a chemiluminescence immunoassay. Solicited local and general symptoms, as well as unsolicited and serious adverse events were recorded after the challenge dose.

RESULTS

303 subjects were enrolled, of whom 302 and 293 subjects formed the total vaccinated and according-to-protocol cohorts, respectively. Pre-challenge, 65.4% (95% CI: 59.6-70.9) subjects were seroprotected (anti-HBs antibody concentration ≥10mIU/mL). One month post-challenge, 97.9% (95% CI: 95.6-99.2) were seroprotected, while 90.8% (95% CI: 86.8-93.8) had anti-HBs antibody concentrations ≥100mIU/mL. The post-challenge geometric mean concentration (GMC; 4134.9 [95% CI: 3114.2-5490.1]) was 150-fold higher than the pre-challenge GMC. Overall, 96.9% (95% CI: 94.2-98.6) subjects mounted an anamnestic response. The safety and reactogenicity profile of the hepatitis B vaccine challenge dose was consistent with previous experience.

CONCLUSIONS

Immunity to hepatitis B persists in 15-16 year old adolescents following primary vaccination in infancy.

TRIAL REGISTRATION

http://www.clinicaltrials.govNCT01847430.

Protection Provided by Hepatitis B Vaccine in Adult Population of Chaharmahal and Bakhtiari Province, Iran in 2013

INTRODUCTION

Hepatitis B vaccination has been integrated into National Expanded Program on Immunization in Iran since the year 1993 and young adult national vaccination project was done in 2008. So we have three subpopulations with vaccination coverage for hepatitis B and different antibody levels. Consisting of Subpopulation 1 born after 1993, subpopulation 2 born between 1989 and 1993 and receiving vaccination under adult national project, and subpopulation 3 born prior to the year 1989.

AIM

The present study was conducted to investigate community protection by hepatitis B vaccine in adult population in an accessible population in Iran and compare vaccination coverage, HBs Ab level, and its effective titration among the three above-mentioned subpopulations.

MATERIALS AND METHODS

This cross-sectional study was done on a 3000-individual adult population from all seven counties of Chaharmahal and Bakhtiari province enrolled by clustering. After obtaining written consent and filling out a questionnaire of demographic data and history of hepatitis B vaccination by trained interviewers, necessary blood sample was taken and HBs Ab titration was checked. The data were analysed by chi-square in SPSS 19. The level of significance was considered as 0.05 and effective Ab titration as ≥ 10.

RESULTS

The mean age of the participants was 38.4±16.3 years. Of the participants 48.2% had effective titration. For vaccination coverage, 77.4% were unvaccinated, 20% completely vaccinated, and 2.6% incompletely vaccinated with a significant association with effective titration (p<0.001). Eighty six percent of the subpopulation 1 and 79% of the subpopulation 2 were completely vaccinated, with a significant difference in effective titration between them (p<0.001). Vaccination coverage was higher in men and the single but equal in cities and villages. The effective titration was significantly associated with being married and residence place (p=0.003). There was a significant association between effective titration and the time at vaccination (p<0.001).

CONCLUSION

Protection provided by hepatitis B vaccine in adult population is relatively suitable especially in the youth population; however, catch-up programs of the groups exposed to risk are recommended.

The Success of a Universal Hepatitis B Immunization Program as Part of Thailand's EPI after 22 Years' Implementation

Hepatitis B vaccination for newborns was introduced in two provinces in 1988 as part of Thailand’s Expanded Program on Immunization (EPI), and extended to the whole country in 1992. Our previous studies showed that children and adolescents who were born after the implementation of this program had a carrier rate of less than 1%, compared with 5–6% before implementation. In 2014 we performed hepatitis B serosurveys among 5964 subjects in the different geographic regions of the country to evaluate the long-term immunogenicity and impact of universal hepatitis B vaccination in newborns as part of the 22-year EPI program, by assessing HBsAg, anti-HBc and anti-HBs seropositivity status. The number of HB virus (HBV) carriers, both children and young adults, who were born after universal HB vaccination was markedly reduced. The carrier rates among the age groups 6 months to 5 years, 5–10, 11–20, 21–30, 31–40, 41–50 and >50 years were respectively 0.1, 0.29, 0.69, 3.12, 3.78, 4.67 and 5.99%. The seropositivity rate for HBsAg in the post-EPI group was 0.6%, whereas in the pre-EPI group it was as high as 4.5% (p<0.001). HBV infection by means of detectable anti-HBc had also drastically declined in the population born after the HB vaccine was integrated into the EPI program. We estimated that the total number of HBV carriers amounted to 2.22 million, or 3.48% of the total population, most of whom are adults. The HB vaccine is the first vaccine shown to be effective in preventing the occurrence of chronic liver disease and hepatocellular carcinoma. Universal vaccination campaign will contribute to the eventual eradication of HBV-associated disease.

Oral delivery of wafers made from HBsAg-expressing maize germ induces long-term immunological systemic and mucosal responses

BACKGROUND

The hepatitis B surface antigen (HBsAg) has been administered over the last 20 years as a parenteral vaccine against the hepatitis B virus (HBV). Despite high seroconversion rates, chronic infection rates are still high worldwide. Orally delivered vaccines provide a practical alternative to injected vaccines, potentially helping poorly responding populations and providing a viable alternative for populations in remote locations. Anamnestic responses are vital to establishing the efficacy of a given vaccine and have been assessed in this study using a plant-based oral delivery platform expressing HBsAg.

METHODS

Long-term immunological memory was assessed in mice injected with a primary dose of Recombivax and boosted with orally-delivered HBsAg wafers, control wafers, or parenterally-delivered commercial vaccine (Recombivax).

RESULTS

Mice boosted with HBsAg orally-administered wafers displayed sharp increases in mucosal IgA titers in fecal material and steep increases in serum IgA, whereas mice boosted with Recombivax showed no detectable levels of IgA in either fecal or serum samples following four boosting treatments. Long-term memory in the orally-treated mice was evidenced by sustained fecal IgA, and serum IgA, IgG, and mIU/mL over one year, while Recombivax-treated mice displayed sustained serum IgG and mIU/mL. Furthermore, sharp increases in these same antibodies were induced after re-boosting at 47 and 50 weeks post-primary injection.

CONCLUSIONS

Orally-delivered vaccines can provide long-term immune responses mucosally and systemically. For sexually-transmitted diseases that can be acquired at mucosal surfaces, such as HBV, an oral delivery platform may provide added protection over a conventional parenterally administered vaccine.

High prevalence of anti-hepatitis B core antigen in hepatitis B virus-vaccinated Chinese blood donors suggests insufficient protection but little threat to the blood supply

BACKGROUND

In East Asia, individuals systematically vaccinated at birth to hepatitis B virus (HBV) are an increasing part of the blood donor population. Their environment presents a high risk of contact with HBV. HBV vaccine efficacy and potential safety risk carried by vaccinated donors were examined.

STUDY DESIGN AND METHODS

A total of 2028 vaccinated blood donors were recruited in 2012 and 2013 and tested for serologic (hepatitis B surface antigen [HBsAg], antibody to hepatitis B surface antigen [anti-HBs], and antibody to hepatitis B core antigen [anti-HBc]) and molecular (HBV DNA) markers of HBV. HBsAg, anti-HBs, and viral load were quantified.

RESULTS

Donors 18 to 21 years systematically vaccinated at birth and 22 to 25 years and older donors had both 30.0% negative serology and 1.8% anti-HBc only but the latter group carried significantly higher prevalence of anti-HBc (p < 0.0001). Anti-HBc, mostly associated with anti-HBs, increased from 10.7% at age 18 to 31.5% at age 25. The level of anti-HBs was significantly higher in anti-HBc-positive donors than in anti-HBs-only donors (p < 0.0001). Samples from 24 donors contained low viral load (25 ± 22 IU/mL), half of them undetected by standard nucleic acid testing (NAT), and were classified as four recent infections, 17 occult HBV infections (OBI), and three primary OBIs. Eighteen of 24 carried anti-HBs; 14 of 15 strains were wild-type Genotype B and one was Genotype C.

CONCLUSIONS

In an environment of frequent high Genotype B or C viremia, blood donors vaccinated at birth are frequently but mildly infected: asymptomatic and normal alanine aminotransferase level, identified by anti-HBc seroconversion and boosting of anti-HBs. Low viral load and frequent anti-HBs limit transfusion risk.

Prevention of Perinatal Hepatitis B Virus Transmission

Hepatitis B virus (HBV) infection, the most common form of chronic hepatitis worldwide, is a major public health problem affecting an estimated 360 million people globally. Mother-to-child transmission (MTCT) is responsible for more than one third of chronic HBV infections worldwide. An estimated 15%-40% of persons chronically infected develop HBV-related complications, such as cirrhosis and hepatic carcinoma, and 25% die from these complications. MTCT can occur during pregnancy or during delivery. Screening pregnant women for HBV infection, providing infant postexposure prophylaxis, and maternal treatment with antiviral medications are strategies for reducing MTCT transmission rates and the global burden of new chronic HBV infections. Administration of hepatitis B immune globulin (HBIG) and hepatitis B (HepB) vaccine within 24 hours of birth, followed by completion of the vaccine series, is 85%-95% efficacious for prevention of MTCT. Despite timely post-exposure prophylaxis, MTCT occurs in 5%-15% of infants. Hepatitis B surface antigen (HBsAg) positive, hepatitis e antigen (HBeAg) positive mothers with HBV DNA level ≥10(6) copies/mL (>200 000 IU/mL) are at greatest risk of transmitting HBV to their infants. Consensus recommendations and evidence-based guidelines for management of chronic HBV infection and screening of pregnant women have been developed. The safety and efficacy of antiviral drug use during pregnancy are areas of ongoing research. Substantial advances have been achieved globally in reducing MTCT, but MTCT remains an ongoing health problem. Attaining a better understanding of the mechanisms of MTCT, implementing existing policies on maternal screening and infant follow-up, and addressing research gaps are critical for further reductions in MTCT transmission.

Vaccination in HIV-infected adults

Vaccines are critical components for protecting HIV-infected adults from an increasing number of preventable diseases. However, missed opportunities for vaccination among HIV-infected persons persist, likely due to concerns regarding the safety and efficacy of vaccines, as well as the changing nature of vaccine guidelines. In addition, the optimal timing of vaccination among HIV-infected adults in regards to HIV stage and receipt of antiretroviral therapy remain important questions. This article provides a review of the current recommendations regarding vaccines among HIV-infected adults and a comprehensive summary of the evidence-based literature of the benefits and risks of vaccines among this vulnerable population.