Impact of hepatitis B immunisation as part of the EPI

Change in Prevalence of Hepatitis B Virus Infection in Pregnant Women in the Last Two Decades in Thailand

Objectives: In Thailand, there has been a strategy to prevent the mother-to-child transmission of HBV for over 30 years. However, there is still a lack of empirical evidence regarding the effectiveness of this strategy. This study aims to investigate the trends in the prevalence of HBV infection in pregnant women and to identify factors that may be associated with the prevalence of HBV infection in pregnant women. Patients and Methods: A maternal-fetal medicine database was accessed to retrieve the consecutive obstetric records of women giving birth at Chiang Mai University Hospital, Thailand, from January 2003 to December 2022. All women undergoing HBV tests with available results were included for an analysis of the trends and changes in the prevalence of maternal HBV infection. Also, the rates of infection in different age cohorts were compared. Results: During the study period, a total of 36,958 women were eligible for analysis. Overall, the prevalence of HBV infection in pregnant women was found to be 5.3% (1970 cases). Overall, HBV prevalence fell from 6.11% in 2003 to 3.15% in 2022. There was a significant reduction, especially in the adolescent group, decreasing from 8.26% in 2003 to 0% in 2022. In the reproductive age group, the prevalence significantly decreased from 6.41% to 2.01%. However, the prevalence in the elderly group was unchanged. The only significant risk factor was the years in the early timeline of the study period, presumably associated with previous HBV vaccination. Other factors, such as socioeconomic status, residential area, and being a private case, were not correlated with the prevalence of HBV. Conclusion: The prevalence of HBV infection in pregnant women has significantly decreased in the past two decades from 6.11% in 2003 to 3.15% in 2022. The percentage of reduction was very striking in the adolescent group, dropping from 8.6% in 2003 to 0.0% in 2022 or being nearly eradicated in the most recent years. Our results suggest that the overall prevalence of HBV infection among our pregnant women will probably be less than 1.0% in the near future.

Hepatitis B prevalence and associated factors in adults presenting for infection screening in northern Thailand

Background and aims

Hepatitis B is a leading cause of morbidity and mortality worldwide. In view of the World Health Organization 2030 targets, effective screening of chronic infection is crucial. We have assessed the prevalence and risk factors of hepatitis B surface antigen in adults presenting for screening.

Methods

Free-of-charge and anonymous services for simultaneous hepatitis B, hepatitis C, human immunodeficiency virus and syphilis screening and counseling were provided in four facilities in northern Thailand. Analyses were performed separately in clients born before integration into the 1992 hepatitis B vaccine Thailand's Expanded Program on Immunization and in clients born afterwards.

Results

Between October 2015 and August 2020, hepatitis B surface antigen prevalence was 7.2 % (185/2578) in clients born before 1992 (95 % confidence interval [CI] = 6.2%-8.2 %). In the multivariable analysis, characteristics independently associated with a higher risk of infection were being born male (adjusted odds ratio [aOR] = 1.49, 95 % CI = 1.10-2.01) and being part of a hill tribe (aOR = 1.65, 95 % CI = 1.01-2.70). Forty-two percent were unaware of their infection. In clients born in 1992 or afterwards, prevalence was 1.5 % (43/2933) (95 % CI = 1.1%-2.0 %) and characteristics independently associated with a higher risk were being born between 1992 and 1995 (aOR = 1.90, 95 % CI = 1.00-3.61), being born male (aOR = 2.60, 95 % CI = 1.34-5.07), being part of a hill tribe (aOR = 5.09, 95 % CI = 2.52-10.26) and having ever injected drugs (aOR = 4.33, 95 % CI = 1.23-15.24).

Conclusions

Risk factor-based screening would miss many chronic hepatitis cases. Screening all adults once in their lifetime may be beneficial until the second generation of immunized infants have reached adult age.

Are International Units of Anti-HBs Antibodies Always Indicative of Hepatitis B Virus Neutralizing Activity?

Objective: Anti-HBs antibodies are elicited upon hepatitis B vaccination, and concentrations above 10 mIU/mL are considered protective. Our aim was to assess the relationship between IU/mL of anti-HBs and neutralization activity. Methods: Immunoglobulins G (IgGs) were purified from individuals who received a serum-derived vaccine (Group 1), a recombinant vaccine, Genevac-B or Engerix-B (Group 2), or who recovered from acute infection (Group 3). IgGs were tested for anti-HBs, anti-preS1, and anti-preS2 antibodies and for their neutralizing activity in an in vitro infection assay. Results: Anti-HBs IUs/mL value did not strictly correlate with neutralization activity. The Group 1 antibodies demonstrated a greater neutralizing activity than those of Group 2. Anti-preS1 antibodies were detected in Groups 1 and 3, and anti-preS2 in Group 1 and Group 2/Genhevac-B, but the contribution of anti-preS antibodies to neutralization could not be demonstrated. Virions bearing immune escape HBsAg variants were less susceptible to neutralization than wild-type virions. Conclusion. The level of anti-HBs antibodies in IUs is not sufficient to assess neutralizing activity. Consequently, (i) an in vitro neutralization assay should be included in the quality control procedures of antibody preparations intended for HB prophylaxis or immunotherapy, and (ii) a greater emphasis should be placed on ensuring that vaccine genotype/subtype matches with that of the circulating HBV.

Immunogenicity of Hepatitis B Vaccine in Pediatric Systemic Lupus Erythematosus Patients

BACKGROUND

Pediatric patients with systemic lupus erythematosus (SLE) are at increased infectious risk caused by underlying immunologic dysregulation and immunosuppressive therapy. Hepatitis B virus (HBV) could be reactivated during the immunosuppressive treatment in patients with past HBV infections. Information on immunogenicity after hepatitis B (HB) immunization and reimmunization are still scarce.

METHODS

SLE patients 5-18 years of age who had completed a primary HB immunization were enrolled. Anti-HBs levels at enrollment and after each vaccine dose were determined. Patients with anti-HBs levels < 10 mIU/mL were administered 1 booster dose. After 1 booster dose, patients with negative anti-HBs levels were administered 2 more booster doses.

RESULTS

Ninety-three SLE patients were enrolled. The prevalence of seroprotection assessed by anti-HBs > 10 mIU/mL after completion of a primary HB immunization was 25.8% (95% CI: 17.2-34.4). Lupus nephritis was associated with unprotective anti-HBs levels [odds ratio (OR): 4.341; 95% CI: 1.044-18.040]. The anti-HBs seroconversion was 72.3% (95% CI: 61.5-83.0) after 1 booster dose and increased up to 93.4% (95% CI: 86.9-98.4) after 3 booster doses. SLE Disease Activity Index-2000 score ≥ 4 (OR: 4.625; 95% CI: 1.45-14.80) was significantly associated with nonseroconversion after the first booster dose. Hypocomplementemia before the first and second booster doses (OR: 27; 95% CI: 1.26-578.35) was significantly associated with nonseroconversion after 3 booster doses.

CONCLUSIONS

All pediatric SLE patients should be evaluated for HBV serological status before immunosuppressive treatment. SLE patients with SLE Disease Activity Index-2000 score > 4 should need 3 booster doses if their anti-HBs level was < 10 mIU/mL.

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.

Recommendation for use of diphtheria and tetanus toxoids and acellular pertussis, inactivated poliovirus, Haemophilus influenzae type b conjugate, and hepatitis B vaccine in infants

In April 2020, the Ministry of Food and Drug Safety licensed a hexavalent combined diphtheria and tetanus toxoids and acellular pertussis (DTaP), inactivated poliovirus (IPV), Haemophilus influenzae type b (Hib) conjugated to tetanus protein, and hepatitis B (HepB) (recombinant DNA) vaccine, DTaP-IPV-Hib-HepB (Hexaxim, Sanofi Pasteur), for use as a 3-dose primary series in infants aged 2, 4, and 6 months. The DTaP-IPV-Hib-HepB vaccine is highly immunogenic and safe and provides a long-term immune response based on studies performed in a variety of settings in many countries, including Korea. This report summarizes the Committee on Infectious Diseases of the Korean Pediatric Society guidelines for the use of this newly introduced hexavalent combination vaccine.

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.

Comparison of hepatitis B surface antibody levels induced by the pentavalent DTwP-HB-Hib versus the hexavalent DTaP-HB-Hib-IPV vaccine, administered to infants at 2, 4, 6, and 18 months of age, following monovalent hepatitis B vaccination at birth

BACKGROUND

In Thailand, the hepatitis B (HB) vaccine is administered as a tetravalent vaccine (DTwP-HB) to all infants at 2, 4, and 6 months of age, following an initial vaccination with a monovalent HB vaccine at birth. As part of ongoing vaccine evaluation, we aimed to compare the hepatitis B immunogenicity profiles of children who had received either the pentavalent (DTwP-HB-Hib) or the hexavalent (DTaP-HB-Hib-IPV) vaccine.

METHODS

Two groups of infants, whose mothers previously received the tetanus-diphtheria-acellular pertussis vaccine (Tdap), were randomly vaccinated with either pentavalent or hexavalent vaccine at 2, 4, 6, and 18 months of age, following monovalent HB vaccine at birth. Blood samples were obtained at birth, one-month post-primary series immunization (mo 7), pre-booster (mo 18), one-month post-booster (mo 19), and six months post-booster (mo 24). The third group of infants, whose mothers did not receive Tdap, was vaccinated with DTwP-HB-Hib (EPI pentavalent group). Levels of HBsAg, anti-HBc, and anti-HBs were evaluated by means of an automated Chemiluminescent Microparticle Immunoassay.

RESULTS

Anti-HBs levels of ≥10 mIU/ml were achieved in 99.2% (hexavalent group), 99.2% (pentavalent group), and 98.5% (EPI pentavalent group) of infants, after four-dose immunization (at 0, 2, 4, 6 months of age). One month after the additional dose given at 18 months of age, anti-HBs levels of ≥10 mIU/ml were observed in 100% (hexavalent group), 99.2% (pentavalent group), and 93.8% (EPI pentavalent group) of infants. At 24 months of age, higher percentages of infants achieving anti-HBs levels ≥10 mIU/ml were found in the hexavalent group (98.3%) compared to the pentavalent group (86.5%).

CONCLUSIONS

Both vaccines were effective in inducing anti-HBs levels of ≥10 mIU/ml, and therefore either can be used as a single formula booster at 18 months of age to simplify vaccine administration under the Expanded Program on Immunization in Thailand.

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.

Persistence of Hepatitis B Immunity Following 3-dose Infant Primary Series in HIV-infected Thai Adolescents and Immunologic Response to Revaccination

BACKGROUND

HIV infection may alter immunologic response and the establishment of immune memory to infant hepatitis B virus (HBV) vaccination. This study aimed to determine the need to revaccinate perinatally HIV-infected Thai adolescents.

METHODS

Cross-sectional serologic tests for HBV, including hepatitis B surface antigen, anti-hepatitis B surface antibody (anti-HBs) and anti-hepatitis B core antibody (anti-HBc), were performed in perinatally HIV-infected adolescents. Adolescents having anti-HBs <100 mIU/mL with negative anti-HBc and immune reconstitution from highly active antiretroviral therapy (HAART) were revaccinated using regular (10 μg) 3-dose schedule given intramuscularly at 0-, 2- and 6-month intervals.

RESULTS

Of 193 adolescents who received 3-dose infant HBV vaccination, 6 were receiving HAART during vaccination, median (interquartile range) current age 14.5 (11.7-16.2) years, 7 (3.6%) had positive anti-HBc (indicating breakthrough infection), of which 4 (2%) had positive hepatitis B surface antigen (indicating chronic infection). Twenty-two (11.4%) adolescents had protective anti-HBs concentration >10 mIU/mL. Of 164 revaccinated adolescents, 142 (86.6%) had HIV viral load <40 copies/mL. Anti-HBs seroconversion rates >10 mIU/mL were 58.0% (94/162) after the first dose and 97.5% (158/162) after the third dose of revaccination. Forty-five (28%) subjects responded to the first dose with anti-HBs antibody ≥100 mIU/mL had a shorter median duration with CD4 count <15% than their counterparts (6.2 vs. 11.1 months; P = 0.049).

CONCLUSIONS

Only half of perinatally HIV-infected adolescents were able to elicit anti-HBs response with a single-dose HBV vaccine. Revaccination with 3-dose schedule is required in perinatally HIV-infected adolescents who did not initiate HAART at the time of infant vaccination.

A review of strategies to prevent mother-to-infant transmission of hepatitis B virus infection

Hepatitis B virus (HBV) infection causes long-term, life-threatening liver diseases worldwide. HBV is transmitted through either the horizontal or mother-to-infant route, which is the major route of transmission in endemic areas. Administration of hepatitis B immunoglobulin and hepatitis B vaccine to newborns of infected mothers prevents mother-to-infant transmission. Implementation of a universal hepatitis B vaccination program has proven successful in eliminating the infection and related complications. Nevertheless, efforts are still needed to improve global coverage of the hepatitis B vaccine. Infants born to highly viremic mothers are still at risk of infection despite current immunoprophylaxis. An increasing number of reports have shown promising efficacy and safety profiles with the use of nucleoside/nucleotide analogues in highly viremic pregnant women to prevent mother-to-infant transmission.

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.

Hepatitis B vaccine alone or with hepatitis B immunoglobulin in neonates of HBsAg+/HBeAg- mothers: a systematic review and meta-analysis

OBJECTIVES

The cost-effectiveness of augmenting immunization against hepatitis B infection with hepatitis B immunoglobulin (HBIG) remains controversial, particularly for the subpopulation of babies of HBsAg+/HBeAg- mothers that are considered as low-infective. We aimed to evaluate the effectiveness of vaccine alone compared with vaccine plus HBIG for the immunization of babies of HBsAg+/HBeAg- mothers.

METHODS

We searched PubMed, Scopus and Cochrane Central Register of Controlled Trials databases to identify studies comparing the effectiveness of combined immunization (vaccine plus HBIG) with vaccine alone in neonates of HBsAg+/HBeAg- mothers. A systematic review and meta-analysis of eligible studies was performed.

RESULTS

A total of nine eligible studies were identified (four randomized controlled trials). No difference was found regarding the primary outcome of our meta-analysis, namely occurrence of hepatitis B infection, between neonates who received vaccine only, compared with those who received both vaccine and HBIG (four studies, 3426 patients, OR=0.82, 95% CI=0.41-1.64). This finding was consistent with regards to seroprotection rate (four studies, 1323 patients, OR=1.24, 95% CI=0.97-1.58). Safety data were not reported in the included studies.

CONCLUSIONS

The available limited published evidence suggests that vaccine alone seems to be equally effective to the combination of HBIG and hepatitis B vaccine for neonates of HBsAg+/HBeAg- mothers in preventing infection. Further studies are needed in order to clarify the potential benefit of combined immunization to this specific subgroup of patients.

Analysis of residual perinatal transmission of hepatitis B virus (HBV) and of genetic variants in human immunodeficiency virus and HBV co-infected women and their offspring

BACKGROUND

Despite implementation of universal infant hepatitis B (HB) vaccination, mother-to-child transmission (MTCT) of hepatitis B virus (HBV) still occurs. Limited data are available on the residual MTCT of HBV in human immunodeficiency virus (HIV)-HBV co-infected women.

OBJECTIVES

We assessed the prevalence of HBV infection among HIV-infected pregnant women and the rate of residual MTCT of HBV from HIV-HBV co-infected women and analyzed the viral determinants in mothers and their HBV-infected children.

STUDY DESIGN

HIV-1 infected pregnant women enrolled in two nationwide perinatal HIV prevention trials in Thailand were screened for HB surface antigen (HBsAg) and tested for HBeAg and HBV DNA load. Infants born to HBsAg-positive women had HBsAg and HBV DNA tested at 4-6 months. HBV diversity within each HBV-infected mother-infant pair was analyzed by direct sequencing of amplified HBsAg-encoding gene and cloning of amplified products.

RESULTS

Among 3312 HIV-1 infected pregnant women, 245 (7.4%) were HBsAg-positive, of whom 125 were HBeAg-positive. Of 230 evaluable infants born to HBsAg-positive women, 11 (4.8%) were found HBsAg and HBV DNA positive at 4-6 months; 8 were born to HBeAg-positive mothers. HBV genetic analysis was performed in 9 mother-infant pairs and showed that 5 infants were infected with maternal HBV variants harboring mutations within the HBsAg "a" determinant, and four were infected with wild-type HBV present in highly viremic mothers.

CONCLUSIONS

HBV-MTCT still occurs when women have high HBV DNA load and/or are infected with HBV variants. Additional interventions targeting highly viremic women are thus needed to reduce further HBV-MTCT.

Hepatitis A and hepatitis B infection prevalence and associated risk factors in men who have sex with men, Bangkok, 2006-2008

Despite the availability of safe and effective vaccines, little is known about prevalence and risk factors for hepatitis A (HAV) and hepatitis B virus (HBV) infection among Thai men who have sex with men. The prevalence of HAV and HBV infection among men who have sex with men cohort in Bangkok was assessed. Baseline blood specimens were drawn and demographic and behavioral data were collected. Bivariate and multivariate logistic regression analysis was used to analyze risk factors for prevalent HAV and HBV infection. One thousand two hundred ninety-nine Thai men who have sex with men 18 years and older were enrolled. Among those with results, 349/1,291 (27.0%) had evidence of past or current hepatitis A infection. Of the 1,117 (86.5%) men with unambiguous HBV test results, 442 (39.6%) had serologic evidence of past/current infection, 103 (9.2%) were immune due to hepatitis B vaccination, 572 (51.2%) had no evidence of immunological exposure to HBV or vaccine. Of those with past/current HBV infection, 130 (29.4%) were HIV positive. Age >35 years was independently associated with both HAV and HBV infection. University education was protective against both HAV and HBV infection. Increased alcohol consumption, number of lifetime male sexual partners ≥10, and prevalent HIV infection were also independently associated with HBV infection. The prevalence of past/current HAV and HBV infection was high in Bangkok men who have sex with men. Age-cohorts with a higher prevalence of hepatitis B vaccine induced immunity may be expected in the future. Hepatitis A and B vaccination is recommended.

Prevalence, risk factors, and impact of isolated antibody to hepatitis B core antigen and occult hepatitis B virus infection in HIV-1-infected pregnant women

BACKGROUND

Prevalence and risk factors for isolated antibody to hepatitis B core antigen (anti-HBc) and occult hepatitis B virus (HBV) infection are not well known in human immunodeficiency virus type 1 (HIV-1)-infected pregnant women. It is unclear if women with occult infections are at risk of transmitting HBV to their infants.

METHODS

HIV-1-infected and HBV surface antigen (HBsAg)-negative pregnant women were tested for antibody to HBsAg (anti-HBs) and anti-HBc using enzyme immunoassay. Women with isolated anti-HBc were assessed for occult HBV infection, defined as HBV DNA levels >15 IU/mL, using the Abbott RealTime HBV DNA assay. Infants born to women with isolated anti-HBc and detectable HBV DNA were tested at 4 months of age for HBV DNA. Logistic regression analysis was used to identify factors associated with isolated anti-HBc and occult HBV infection.

RESULTS

Among 1812 HIV-infected pregnant women, 1682 were HBsAg negative. Fourteen percent (95% confidence interval [CI], 12%-15%) of HBsAg-negative women had an isolated anti-HBc that was independently associated with low CD4 count, age >35 years, birth in northern Thailand, and positive anti-hepatitis C virus serology. Occult HBV infection was identified in 24% (95% CI, 18%-30%) of women with isolated anti-HBc, representing 2.6% (95% CI, 1.9%-3.5%) of HIV-1-infected pregnant women, and was inversely associated with HIV RNA levels. None of the women with isolated anti-HBc and occult HBV infection transmitted HBV to their infants.

CONCLUSIONS

HIV-1-infected pregnant women with isolated anti-HBc and occult HBV infection have very low HBV DNA levels and are thus at very low risk to transmit HBV to their infants.

Aflatoxin-induced TP53 R249S mutation in hepatocellular carcinoma in Thailand: association with tumors developing in the absence of liver cirrhosis

Primary Liver Cancer (PLC) is the leading cause of death by cancer among males in Thailand and the 3(rd) among females. Most cases are hepatocellular carcinoma (HCC) but cholangiocarcinomas represent between 4 and 80% of liver cancers depending upon geographic area. Most HCC are associated with chronic infection by Hepatitis B Virus while a G → T mutation at codon 249 of the TP53 gene, R249S, specific for exposure to aflatoxin, is detected in tumors for up to 30% of cases. We have used Short Oligonucleotide Mass Analysis (SOMA) to quantify free circulating R249S-mutated DNA in plasma using blood specimens collected in a hospital case:control study. Plasma R249S-mutated DNA was detectable at low concentrations (≥ 67 copies/mL) in 53 to 64% of patients with primary liver cancer or chronic liver disease and in 19% of controls. 44% of patients with HCC and no evidence of cirrhosis had plasma concentrations of R249S-mutated DNA ≥ 150 copies/mL, compared to 21% in patients with both HCC and cirrhosis, 22% in patients with cholangiocarcinoma, 12% in patients with non-cancer chronic liver disease and 3% of subjects in the reference group. Thus, plasma concentrations of R249S-mutated DNA ≥ 150 copies/mL tended to be more common in patients with HCC developing without pre-existing cirrhosis (p = 0.027). Overall, these results support the preferential occurrence of R249S-mutated DNA in HCC developing in the absence of cirrhosis in a context of HBV chronic infection.

Aflatoxin-induced TP53 R249S mutation in hepatocellular carcinoma in Thailand: association with tumors developing in the absence of liver cirrhosis

Primary Liver Cancer (PLC) is the leading cause of death by cancer among males in Thailand and the 3^rd among females. Most cases are hepatocellular carcinoma (HCC) but cholangiocarcinomas represent between 4 and 80% of liver cancers depending upon geographic area. Most HCC are associated with chronic infection by Hepatitis B Virus while a G→T mutation at codon 249 of the TP53 gene, R249S, specific for exposure to aflatoxin, is detected in tumors for up to 30% of cases. We have used Short Oligonucleotide Mass Analysis (SOMA) to quantify free circulating R249S-mutated DNA in plasma using blood specimens collected in a hospital case:control study. Plasma R249S-mutated DNA was detectable at low concentrations (≥67 copies/mL) in 53 to 64% of patients with primary liver cancer or chronic liver disease and in 19% of controls. 44% of patients with HCC and no evidence of cirrhosis had plasma concentrations of R249S-mutated DNA ≥150 copies/mL, compared to 21% in patients with both HCC and cirrhosis, 22% in patients with cholangiocarcinoma, 12% in patients with non-cancer chronic liver disease and 3% of subjects in the reference group. Thus, plasma concentrations of R249S-mutated DNA ≥150 copies/mL tended to be more common in patients with HCC developing without pre-existing cirrhosis (p = 0.027). Overall, these results support the preferential occurrence of R249S-mutated DNA in HCC developing in the absence of cirrhosis in a context of HBV chronic infection.

Hepatocellular carcinoma: focus on different aspects of management

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third cause of cancer-related mortality worldwide. Its incidence is clearly arising comprised by the prevalence of major risk factors mainly hepatitis B and hepatitis C. The population at risk is composed of chronic liver patients at the stage of extensive fibrosis or cirrhosis. The monitoring programs of this population have allowed early detection of disease management to promote a radical therapy. Understanding the carcinogenic process and the mastery of the staging systems remain essential keys in diagnosis and treatment of HCC. Recent advances in diagnosis and new treatments have made important impacts on the disease by increasing survival rates and improving quality of life for HCC patients. This paper outlines the different management aspects of HCC which include epidemiology, prevention, carcinogenesis, staging systems, diagnosis, surveillance, and the treatment.

Effects of maternal screening and universal immunization to prevent mother-to-infant transmission of HBV

BACKGROUND & AIMS

Mother-to-infant transmission is the major cause of hepatitis B virus (HBV) infection among immunized children. There has been much debate about screening pregnant women and administering hepatitis B immunoglobulin (HBIG) to newborns. We analyzed the rate of HBV infection among children born to hepatitis B surface antigen (HBsAg)-positive mothers and whether HBIG administration reduces transmission.

METHODS

We analyzed data from 2356 children born to HBsAg-positive mothers, identified through prenatal maternal screens. In addition to HBV vaccines, HBIG was given to all 583 children with hepatitis B e antigen (HBeAg)-positive mothers and to 723 of 1773 children with HBeAg-negative mothers. Serology tests for HBV were performed from 2007 to 2009, when children were 0.5-10 years old.

RESULTS

A significantly greater percentage of children with HBeAg-positive mothers tested positive for antibodies against the hepatitis B core protein (16.76%) and HBsAg (9.26%) than children with HBeAg-negative mothers (1.58% and 0.29%, respectively; P < .0001 and <.001). Among the HBV-infected children, the rate of chronicity also was higher among children with HBeAg-positive mothers than children with HBeAg-negative mothers (54% vs 17%; P = .002). Similar rates of antibodies against the hepatitis B core protein (0.99% and 1.88%; P = .19) and HBsAg (0.14% and 0.29%; P = .65) were noted in children born to HBeAg-negative mothers who were or were not given HBIG. Infantile fulminant hepatitis developed in 1 of 1050 children who did not receive HBIG (.095%).

CONCLUSIONS

Children born to HBeAg-positive mothers are at greatest risk for chronic HBV infection (9.26%), despite immunization. Administration of HBIG to infants born to HBeAg-negative mothers did not appear to reduce the rate of chronic HBV infection, but might prevent infantile fulminant hepatitis. Screening pregnant women for HBsAg and HBeAg might control mother-to-infant transmission of HBV.

Hepatitis B virus and cancer prevention

Prevention of chronic hepatitis B virus (HBV) infection can successfully reduce the incidence of liver cancer. It is the first example of cancer-preventive vaccine in human, which proves that prevention of the infection of an infectious agent can prevent its related cancer.Chronic HBV infection can lead to chronic hepatitis, liver cirrhosis, and hepatocellular carcinoma (HCC). HCC is one of the five major cancers in the world population. Hepatitis B virus (HBV) is the most important etiologic agent of liver cancer globally, particularly in high-prevalence areas of liver cancer.The world's first universal HBV vaccination program was launched in Taiwan in July 1984. It has provided evidences that the prevalence of HBV infection has been reduced remarkably to approximately one-tenth of the original prevalence. Furthermore, reduction of the HCC incidence in children aged 6-14 years have been demonstrated in the vaccinated birth cohorts. Recently, we have further provided evidence that the prevention of HCC by this HBV vaccine extends from childhood to early adulthood.The risk of developing HCC for vaccinated cohorts was associated with incomplete HBV vaccination; prenatal maternal hepatitis B surface antigen (HBsAg) seropositivity; and prenatal maternal HBeAg seropositivity. Failure to prevent HCC results mostly from unsuccessful control of HBV infection by highly infectious mothers. Future strategies to increase the global coverage rate of HBV immunization and to interrupt mother-to- infant transmission may enhance the cancer prevention effect of HBV immunization.

Hepatitis B vaccination: disease and cancer prevention-a Taiwanese experience

Prevention is most cost effective toward successful control of hepatitis B virus (HBV) infection and its complications. It is particularly urgent where HBV infection and hepatocellular carcinoma (HCC) are prevalent. To achieve better results of primary HCC prevention globally, higher world coverage rates of HBV vaccine, better strategies against breakthrough infection/nonresponder, and good long-term protection are needed. With the universal hepatitis B vaccination program starting from neonates in most countries, HBV infection and its complications will be further reduced in this century. An effective decline in the incidence of HCC in adults is expected in the near future. The concept of a cancer preventive vaccine, using HBV as an example, can be applied further to other infectious agents and their related cancers.

Management of hepatocellular carcinoma in Asia: consensus statement from the Asian Oncology Summit 2009

Asia has a disproportionately large share of the world's hepatocellular carcinoma (HCC), mainly because of the endemic status of chronic hepatitis B and C viruses, which leads to liver cirrhosis and an increased risk of HCC. This etiological factor presents important opportunities for prevention, early detection, diagnosis, and treatment of HCC. This consensus statement reviews the available medical evidence for management of HCC in Asia, and gives treatment recommendations that are adapted to resource availability in this diverse region with disparate health-care delivery systems.

Control of hepatocellular carcinoma through hepatitis B vaccination in areas of high endemicity: perspectives for global liver cancer prevention

There are approximately 360 millions chronic carriers of Hepatitis B virus worldwide. Patterns of HB carriage are variable from one region to the other. Regions with rates of carriage over 8% are commonly considered as "high endemicity" regions. HB carriers have a very significant lifetime risk of developing chronic liver diseases such as cirrhosis and/or liver cancer (hepatocellular carcinoma, HCC). An efficient HB vaccine is available since the early eighties and has been used since for universal infant vaccination in regions of high endemicity. Observations from Taiwan, where universal infant vaccination was introduced from 1984, show a remarkable, long-lasting protection against carriage and reduction of HCC rates in adolescent and young adults born after the initiation of the programme. Two population-based trials have been set up in the mid-eighties to evaluate lifelong protective effects of infant HB vaccine against liver cancer, in The Gambia (West Africa) and in the area of Qidong, China. In other high-endemicity regions of Asia and Africa, universal infants vaccination has consistently showed a long-lasting high protection against chronic carriage and this is expected to lead to a dramatic decrease of chronic liver disease and liver cancer within the next decades. Here we briefly review the lessons of vaccination programmes and trials in high-endemicity regions, based on data gathered during 15-20years of implementation.

Increased risk of developing chronic HBV infection in infants born to chronically HBV infected mothers as a result of delayed second dose of hepatitis B vaccination

This two-stage study (cross-sectional and case-control) assessed the effects of delayed second dose HB vaccination on the risk of developing chronic HBV infection in infants born to chronically HBV infected mothers. 521 infants enrolled received the first vaccination by the end of the day after birth, without HBIG. 15 of these infants were chronically HBV infected. In the case-control comparison, controlling for HBeAg in the mother, the risk of an infant becoming chronically infected was 3.74 times (95% CI=0.97-14.39) higher if the interval between the first and the second doses exceeded 10 weeks. This finding suggests it is important that immunization programs ensure timely second dose vaccination to infants born to mothers with chronic HBV infection. Nevertheless, due to the small sample size, these findings should be verified by larger studies.

Hepatitis B vaccination: The key towards elimination and eradication of hepatitis B

Hepatitis B virus infection is a global health problem. Worldwide, about 360 million people are chronically infected with the virus. They continue to spread the virus to others and are themselves at risk of chronic liver diseases and hepatocellular carcinoma. The infection can now be treated by antivirals or interferons and the transmission route can be interrupted. Nevertheless, the most effective means is to immunize all susceptible individuals, especially young children, with safe and efficacious vaccines. The combined efforts of vaccination, effective treatment and interruption of transmission make elimination of the infection plausible and may eventually lead to eradication of the virus. Because hepatitis B vaccination has a key role in the control of hepatitis B, properties of this vaccine, its effectiveness in pre-exposure and post-exposure settings, duration of protection after vaccination and the need of booster doses are discussed. Mass hepatitis B vaccination in children decreases the carriage of the virus, and the diseases associated with acute and chronic infection, including hepatocellular carcinoma. Challenges that need to be solved to expand mass vaccination, and the strategies towards elimination and eventual eradication of hepatitis B in the world are also discussed.

Epidemiology of hepatitis B virus infection in Albania

AIM: To assess the prevalence and socio-demographic distribution of hepatitis B virus (HBV) infection in Albania.

METHODS: Blood samples from 410 unselected schoolboys, 666 students, 500 military personnel, 1286 casual blood donors, 378 voluntary blood donors and 640 pregnant women (total 3880 non-vaccinated residents of rural and metropolitan areas from all over Albania; 2354 (60.7%) male and 1526 (39.3%) female; mean age of 26.3 years) were tested during 2004-2006 for hepatitis B surface antigen (HBsAg) and antibodies to hepatitis B virus (anti-HBs) by ELISA.

RESULTS: The HBsAg and anti-HBs prevalence were 9.5% and 28.7%, respectively. The highest HBsAg prevalence was evident in the younger age group, such as in schoolchildren (11.8%) and the military (10.6%). Consequently, the anti-HBs prevalence increased with age, from 21.2% in schoolchildren (mean age: 15.7 years), to 36.3% in pregnant women (mean age: 26.3 years) and 29.7% in voluntary blood donors (mean age: 40.1 years). There were no significant differences between males and females.

CONCLUSION: Despite the estimated two-fold reduction of HBsAg prevalence in the general population from about 18%-19% to 9.5%, Albania remains a highly endemic country (i.e. over 8% of HBsAg prevalence rate).

[Hepatitis B in pregnant women and children]

In pregnant women and children, the hepatitis B virus can cause acute or chronic hepatitis or liver cirrhosis. Perinatally-acquired infection causes persistent infection in 90% of cases and can be avoided through administration of the hepatitis B vaccine and specific immunoglobulin in the first day of life. Prevention of mother-to-child transmission requires screening for hepatitis B surface antigen (HBsAg) in pregnant women to identify which newborns should be immunized. In some countries this strategy is substituted by universal vaccination of neonates. In infected children, inactivation of viral replication with conversion of HBeAG-positive to anti-HBe-positive status usually occurs. If this seroconversion does not take place and necroinflammatory activity persists in the liver, the use of antiviral agents such as interferon or nucleoside and nucleotide analogs is warranted.

Prevalence of hepatitis B, tetanus, hepatitis A, human immunodeficiency virus and feasibility of vaccine delivery among injecting drug users in Bangkok, Thailand, 2003-2005

OBJECTIVES

To estimate the prevalence of hepatitis B virus (HBV), tetanus, hepatitis A virus (HAV) and human immunodeficiency virus (HIV) in injecting drug users (IDUs), risk factors associated with infection and the feasibility of HBV vaccine delivery in HBV seronegatives.

METHODS

Cross-sectional seroprevalence survey of 1535 IDUs recruited from 17 Bangkok Metropolitan Administration (BMA) methadone clinics and HBV vaccination of seronegatives.

RESULTS

Prevalence of antibody to HBV, tetanus, HAV and HIV was 87.8%, 68.1%, 60.2% and 35.9%, respectively. Prevalence of HBV and HAV increased with increasing age; prevalence of tetanus decreased with increasing age. Being HIV seropositive was related inversely to income and being tetanus seronegative. Of the 189 HBV seronegative IDUs, 81.0% completed the vaccine series. IDUs with HIV had a 6.5-fold odds of vaccine non-response.

CONCLUSIONS

These data underscore the need for, and feasibility of, vaccine delivery in this population and support targeting efforts at high-risk age groups.

Molecular epidemiological study of hepatitis B virus in Thailand based on the analysis of pre-S and S genes

AIMS

This study was undertaken to determine the prevalence and characteristics of hepatitis B virus (HBV) genotypes, antigen subtypes, "a" determinant variants and pre-S gene mutations circulating on a large scale in Thailand.

METHODS

The sequences of the Pre-S1, Pre-S2 and S regions were determined in serum samples of 147 HBsAg and HBV DNA-positive subjects who had been enrolled from the nationwide seroepidemiological survey conducted on 6213 individuals in 2004.

RESULTS

The results showed that genotypes C, B and A accounted for 87.1%, 11.6% and 1.3%, respectively. The distribution of the HBV antigen subtypes was: adr (84.4%), adw (14.2%) and ayw (1.4%). Regarding the "a" determinant, 2/43 (4.65%) and 2/104 (1.92%) samples of vaccinated and non-vaccinated subjects, respectively, displayed mutations, all ofwhich were Thr126Asn. Sequencing analysis showed the pre-S mutations in 14 (9.5%) samples, with pre-S2 deletion as the most common mutant (4.1%) followed by pre-S2 start codon mutation (2.9%), both pre-S2 deletion and start codon mutation (2.0%), and pre-S1 deletion (0.7%). The pre-S mutations were associated with older age and higher mean serum HBsAg level.

CONCLUSION

This study demonstrated that HBV genotype/subtype C/adr and B/adw were the predominant strains circulating in Thailand. The "a" determinant variants seemed to be uncommon, and might not be attributed to vaccine-induced mutation.

Eight years of hepatitis B vaccination in Colombia with a recombinant vaccine: factors influencing hepatitis B virus infection and effectiveness

OBJECTIVE

To evaluate the effectiveness of a recombinant hepatitis B vaccine used in endemic areas of Colombia, as well as risk factors associated with hepatitis B virus (HBV) infection and carriage after vaccine introduction.

METHODS

A cross-sectional study was carried out in urban and rural areas of the Colombian Amazon, a highly endemic area for hepatitis B infection. Children under 12 years of age and their mothers were selected for the study using one-stage cluster sampling (N=2145) and were examined for HBV serological markers and antibodies against surface antigen (anti-HBs).

RESULTS

There has been a reduction of 60-75% in the prevalence of HBV infection and hepatitis B surface antigen (HBsAg) carriage since HBV vaccination was introduced. Receiving the first dose of HBV vaccine at more than two months after birth was one of the factors associated with HBV carrier status. Maternal HBV infection was also associated with infection in the child.

CONCLUSIONS

The recombinant Cuban hepatitis B vaccine has contributed to the reduction of the infection in this highly endemic area, though further efforts are required to improve timely vaccination for children at high risk.

What influences government adoption of vaccines in developing countries? A policy process analysis

This paper proposes a framework for examining the process by which government consideration and adoption of new vaccines takes place, with specific reference to developing country settings. The cases of early Hepatitis B vaccine adoption in Taiwan and Thailand are used to explore the relevance of explanatory factors identified in the literature as well as the need to go beyond a variable-centric focus by highlighting the role of policy context and process in determining the pace and extent of adoption. The cases suggest the feasibility and importance of modeling 'causal diversity'-the complex set of necessary and sufficient conditions leading to particular decisional outcomes-in a broad range of country contexts. A better understanding of the lenses through which government decision-makers filter information, and of the arenas in which critical decisions are shaped and taken, may assist both analysts (in predicting institutionalization of new vaccines) and advocates (in crafting targeted strategies to accelerate their diffusion).

Impact of the universal hepatitis B immunization program in Mongolia: achievements and challenges

BACKGROUND

The impact of the universal infant hepatitis B (HB) immunization program initiated in 1991 in Mongolia is still unclear.

METHODS

A nationwide school-based cross-sectional serosurvey was conducted in 2004, with stratified, multistage, random cluster sampling from all public elementary schools (n=593) in Mongolia. All children were tested for serological markers of hepatitis B virus (HBV).

RESULTS

Serology results were available for 1,145 children (592 boys and 553 girls) aged 7-12 years (survey response rate: 93%). Immunization card was available for 702 (61.3%) children. The coverage of complete HB vaccination was 60.1% and it was increased by birth cohort from 44% to 76%. Significantly higher proportion of children in Metropolitan cities (75.2%) was completely vaccinated with HB compared to those in Province centers (55.7%) and rural areas (59.1%). HBV infection occurred in 5.9%, 13.2%, and 20.8% of complete vaccinees living in Metropolitan, Province centers, and rural areas, respectively; of whom 1.2%, 2.9%, and 8.6% were HB surface antigen (HBsAg) carriers, respectively. Only 17.0% of the children had protective anti-HBs which decreased from 31.1% to 16.3% among 7 to 12-year-olds indicating its decay with time.

CONCLUSIONS

Prevalence of HBV infection and carriage among young generation meaningfully declined compared with those of previous studies in Mongolia. The coverage of birth dose and complete HB vaccination was significantly low in Province centers and rural areas which should be taken into consideration.

Antibody response to hepatitis B re-vaccination in HIV-infected children with immune recovery on highly active antiretroviral therapy

Despite a history of hepatitis B virus (HBV) vaccination prior to highly active antiretroviral therapy (HAART), most of HIV-infected children do not have protective antibody to HBV infection. The efficacy of an additional booster dose in children with immune recovery on HAART remains unknown. This study was conducted to determine the response rate of HBV antibody after re-vaccination in HIV-infected children with immune recovery on HAART. Sixty-three successfully HAART-treated HIV-infected children with history of prior HBV vaccination received 10microg doses of recombinant HBV vaccine (Government Pharmaceutical Organization-Merieux Biological Product, Bangkok, Thailand) intramuscularly at 0, 2 and 6 months. The vaccine response rates were 17.4, 82.5, and 92.1% at 2, 6 and 7 months after the first dose of vaccine, respectively. Plasma HIV RNA level below the limit of detection at the time of re-vaccination was associated with successful vaccine response. HIV-infected children with immune recovery after HAART are likely to benefit from three-dose HBV re-vaccination.

Hepatitis B virus infection

Hepatitis B virus (HBV) infection is a worldwide health problem and may cause acute, fulminant, chronic hepatitis, liver cirrhosis, or hepatocelullar carcinoma (HCC). Infection with HBV in infancy or early childhood may lead to a high rate of persistent infection (25-90%), while the rates are lower if infection occurs during adulthood (5-10%). In most endemic areas, infection occurs mainly during early childhood and mother-to-infant transmission accounts for approximately 50% of the chronic infection cases. Hepatitis B during pregnancy does not increase maternal mortality or morbidity or the risk of fetal complications. Approximately 90% of the infants of HBsAg carrier mothers with positive hepatitis B e-antigen (HBeAg) will become carriers if no immunoprophylaxis is given. Transplacental HBeAg may induce a specific non-responsiveness of helper T cells and HBcAg. Spontaneous HBeAg seroconversion to anti-HBe may develop with time but liver damage may occur during the process of the immune clearance of HBV and HBeAg. Mother-to-infant transmission of HBV from HBeAg negative but HBsAg positive mothers is the most important cause of acute or fulminant hepatitis B in infancy. Although antiviral agents are available to treat and avoid the complications of chronic hepatitis B, prevention of HBV infection is the best way for control. Screening for maternal HBsAg with/without HBeAg, followed by three to four doses of HBV vaccine in infancy and hepatitis B immunoglobulin (HBIG) within 24h of birth is the most effective way to prevent HBV infection. In areas with a low prevalence of HBV infection or with limited resources, omitting maternal screening but giving three doses of HBV vaccine universally in infancy can also produce good protective efficacy. The first universal HBV immunisation programme in the world was launched in Taiwan 22 years ago. HBV infection rates, chronicity rates, incidence of HCC and incidence of fulminant hepatitis in children have been effectively reduced.

Seroepidemiology of hepatitis B virus infection among children in Mongolia: results of a nationwide survey

BACKGROUND

Because Mongolia is one of the highly endemic countries for hepatitis B virus (HBV) infection in the world, hepatitis B (HB) vaccine was introduced into the National Expanded Program on Immunization in 1991. However, relatively few data are available concerning HBV infection among children born after the start of the program, so far. The aim of the present paper was to describe the seroepidemiology of HBV infection among primary school children using representative national data.

METHODS

In 2004, a nationwide school-based cross-sectional serosurvey was carried out throughout Mongolia, covering both urban and rural areas. Serum samples were tested for hepatitis B surface antigen (HBsAg), antibody to hepatitis B core antigen (anti-HBc) and hepatitis B e antigen (HBeAg) as well as for liver enzymes.

RESULTS

A total of 1145 children aged 7-12 years were studied, which represents nearly 2% of the second grade population of elementary schools in Mongolia. The overall prevalence of HBsAg and anti-HBc was 5.2% (95% confidence interval [CI]: 3.9-6.5%) and 15.6% (95%CI: 13.5-17.7%), respectively. Among HBsAg-positive children 67.8% (95%CI: 55.9-79.7%) were also positive for HBeAg. The prevalence of chronic HBV infection increased by age and was significantly higher among children from rural areas compared to those from urban areas (7.7% vs 3.0%; P < 0.001). In the multivariate logistic regression analysis, rural residence (odds ratio [OR]: 2.57; 95%CI: 1.45-4.58), male sex (OR: 1.9; 95%CI: 1.08-3.26) and age (OR: 1.5; 95%CI: 1.10-2.05) were independent demographic predictors for chronic HBV infection.

CONCLUSIONS

The prevalence of chronic HBV infection has been decreasing in the Mongolian young generation, most likely due to infant HB vaccination. However, significant rural-urban differences in the prevalence of HBV infection were found that demand further investigation to estimate the potential causes.

Hepatitis B seroprevalence in Thailand: 12 years after hepatitis B vaccine integration into the national expanded programme on immunization

OBJECTIVES

To evaluate the impact of the universal hepatitis B (HB) vaccination programme on the prevalence of hepatitis B surface antigen (HBsAg) carriers and immunity to HB virus infection among children <18 years and to determine the HB seroprevalence in the Thai population.

METHODS

We enrolled people in four provinces, including Chiangrai, Udon Thani, Chonburi and Nakhon Si Thammarat to geographically represent populations in the North, Northeast, Center and South of the country respectively. Serology for HBsAg, anti-hepatitis B surface (anti-HBs), and anti-hepatitis B core (anti-HBc) was tested using ELISA commercial kits. In total, 6213 subjects aged 6 months to 60 years from the four provincial hospitals and two to three district hospitals of each participating province participated.

RESULTS

Overall HBsAg, anti-HBs, and anti-HBc seropositive rates amounted to 4%, 41.6% and 26.5% respectively. Of 2887 participants aged 6 months to 18 years, 2303 were born after (group I) and 584 prior to (group II) HB vaccine integration into the expanded programme on immunization of each participating province. The HBsAg seropositive rate was 0.7% among group I children and 4.3% among group II children. The prevalence rate of anti-HBc was 2.9% in group I and 15.8% in group II. In children under 18 years, the HBsAg carrier rate was 0.98% among complete vaccinees and 1.36% among participants without vaccination.

CONCLUSIONS

This finding supports the efficacy of universal HB immunization in reducing the prevalence of HB infection in Thailand which is a highly endemic country.

Seroconversion of hepatitis B vaccine in infants related to the mother's serostatus in a community of São José dos Campos, state of São Paulo, Brazil

PURPOSE

To detect seroconversion of hepatitis B vaccine and antibody waning 3 years after vaccination in children immunized according to the World Health Organization schedule and its relationship to the mother's serostatus during pregnancy.

METHODS

A serological study was carried out in São José dos Campos. Blood samples from pregnant women were taken for hepatitis B marker serology. To evaluate seroconversion in infants born to these women, serology was performed 1 month after they were vaccinated with recombinant vaccine. Another group of children was evaluated 3 years after being immunized.

RESULTS

Among 224 pregnant women, 0.9% were positive for hepatitis B surface antigen, 8.0% for antibodies to the surface antigen, and 4.5% for antibodies to the virus core. Seroconversion among 174 infants was as follows: absent in 18 children (10.35%), low level in 15 (8.62%), intermediate level in 26 (14.94%), and a high level (good response) in 115 (66.09%). Antibody positivity after 3 years was as follows: absent in 8 children (7.92%), low level in 51 (50.5%), intermediate level in 20 (19.8%), and high level in 22 (21.78%). Considering the age that the vaccine was administered, a significant proportion of non-seroconverters was found among children who had received the complete 3-dose schedule before 9 months (P = 0.023). Another factor that significantly contributed to the lack of seroconversion was the presence of any serological marker for hepatitis B during pregnancy (P = 0.044).

CONCLUSIONS

Data gathered in this work show that the immunization schedule for hepatitis B in low or moderate prevalence areas should be revised in order to optimize seroconversion.

Prevalence of hepatitis B surface antigen in vaccinated children and controls in rural Nigeria

OBJECTIVE

To determine the prevalence of hepatitis B surface antigen (HBsAg) amongst vaccinated children and controls aged 1-4 years in a rural community in mid-western Nigeria.

METHODS

The vaccinated children had received at least three doses of hepatitis B vaccine. The vaccines included recombinant hepatitis B vaccine at birth and a combined diphtheria, tetanus, pertussis (whole cell) plus hepatitis B (DTPw-HBV) vaccine. HBsAg was determined by a rapid immunoassay method based on the immunochromatographic sandwich principle. Two hundred and twenty-three children and 219 controls were recruited into the study.

RESULTS

The prevalence of HBsAg was significantly lower in the vaccinated group (1.3%) than in the control group (4.6%, p=0.04). The prevalence rates were significantly higher in males (p=0.02) and two-year birth cohort (p=0.01). The controls were estimated to be at a six-fold higher risk of being positive for the surface antigen than the vaccinated children. The vaccine effectiveness was estimated to be approximately 80%.

CONCLUSION

These results confirm that hepatitis B vaccine protects against hepatitis B surface antigen carriage and confirm immunogenicity of the combined DTPw-HBV vaccine.

A quasi-monoclonal anti-HBs response can lead to immune escape of ‘wild-type’ hepatitis B virus

Hepatitis B virus (HBV) infections can be prevented or controlled by the host humoral immune response (anti-HBs) directed against the major surface antigen (HBsAg), elicited either naturally or by vaccination. A chronic HBV carrier was found to have high levels of both virus and anti-HBs. Full-length HBV genomes were amplified from the patient's serum, sequenced and cloned. The genome was ‘wild-type’ HBV of genotype C and serotype adr. The sequence has remained stable, with no signs of emergence of an immune-escape mutant population. To study what was recognized by the patient's serum, viral particles were 35S-labelled and then immunoprecipitated by using the patient's serum or control sera. The patient's serum immunoprecipitated the adr HBsAg encoded by his HBV genome poorly, but efficiently recognized HBsAg of serotype ayw. When his HBV genome was modified by a point mutation to express HBsAg of serotype ayr, the patient's serum could recognize the antigen, as well as the control anti-HBs-positive serum. The patient appeared to have made a quasi-monoclonal humoral response to the y epitope. By switching to the d epitope, which requires only a point mutation, the virus could replicate, despite the high levels of anti-HBs. This study underlines the subtleties of virus–host interactions. Implications for HBV vaccination are discussed.

Long-term efficacy of hepatitis B vaccine, booster policy, and impact of hepatitis B virus mutants

The long-term efficacy of hepatitis B vaccine, long-term effectiveness of hepatitis B immunisation programmes, immune memory induced by hepatitis B vaccine, current booster policies, and impact of hepatitis B virus mutants on immunisation programmes were reviewed at the Viral Hepatitis Prevention Board (VHPB) meeting in Sevilla, Spain, March 2004. The main focus was on universal vaccination programmes with data being presented from Italy, Saudi Arabia, Singapore, Spain, Taiwan, Thailand, The Gambia, and USA (Alaska).

Community-based interventions for improving perinatal and neonatal health outcomes in developing countries: a review of the evidence

BACKGROUND

Infant and under-5 childhood mortality rates in developing countries have declined significantly in the past 2 to 3 decades. However, 2 critical indicators, maternal and newborn mortality, have hardly changed. World leaders at the United Nations Millennium Summit in September 2000 agreed on a critical goal to reduce deaths of children <5 years by two thirds, but this may be unattainable without halving newborn deaths, which now comprise 40% of all under-5 deaths. Greater emphasis on wide-scale implementation of proven, cost-effective measures is required to save women's and newborns' lives. Approximately 99% of neonatal deaths take place in developing countries, mostly in homes and communities. A comprehensive review of the evidence base for impact of interventions on neonatal health and survival in developing-country communities has not been reported.

OBJECTIVE

This review of community-based antenatal, intrapartum, and postnatal intervention trials in developing countries aimed to identify (1) key behaviors and interventions for which the weight of evidence is sufficient to recommend their inclusion in community-based neonatal care programs and (2) key gaps in knowledge and priority areas for future research and program learning.

METHODS

Available published and unpublished data on the impact of community-based strategies and interventions on perinatal and neonatal health status outcomes were reviewed. Evidence was summarized systematically and categorized into 4 levels of evidence based on study size, location, design, and reported impact, particularly on perinatal or neonatal mortality. The evidence was placed in the context of biological plausibility of the intervention; evidence from relevant developed-country studies; health care program experience in implementation; and recommendations from the World Health Organization and other leading agencies.

RESULTS

A paucity of community-based data was found from developing-country studies on health status impact for many interventions currently being considered for inclusion in neonatal health programs. However, review of the evidence and consideration of the broader context of knowledge, experience, and recommendations regarding these interventions enabled us to categorize them according to the strength of the evidence base and confidence regarding their inclusion now in programs. This article identifies a package of priority interventions to include in programs and formulates research priorities for advancing the state of the art in neonatal health care.

CONCLUSIONS

This review emphasizes some new findings while recommending an integrated approach to safe motherhood and newborn health. The results of this study provide a foundation for policies and programs related to maternal and newborn health and emphasizes the importance of health systems research and evaluation of interventions. The review offers compelling support for using research to identify the most effective measures to save newborn lives. It also may facilitate dialogue with policy makers about the importance of investing in neonatal health.

Practical difficulties in the management of hepatitis B in the Asia-Pacific region

The Asia-Pacific Expert Committee on Hepatitis B Management recently reviewed the impact of hepatitis B in the region and assessed the differences and similarities observed in the practical management of the disease in individual Asia-Pacific countries. Hepatitis B is a major health concern in the Asia-Pacific region, and of all chronically infected carriers worldwide, approximately 75% are found in Asia. The disease poses a considerable burden on healthcare systems, and is likely to remain a cause of substantial morbidity and mortality for several decades. Disease prevention activities, including screening and vaccination programs, have been implemented successfully in some Asia-Pacific countries and similar measures are being established in other parts of the region. The management of hepatitis B in the Asia-Pacific varies throughout the region, with each country confronting different issues related to treatment options, disease monitoring and duration of therapy. The influence of cost, availability of diagnostic equipment, and patient awareness and compliance are of additional concern. Although guidelines such as those developed by the Asian Pacific Association for the Study of the Liver have been created to address problems encountered in the management of hepatitis B, many physicians in the region still find it difficult to make satisfactory management decisions because of the treatment choices available. This article examines the different approaches to hepatitis B management in a number of Asia-Pacific countries, and highlights the difficulties that can arise when adhering to treatment guidelines and disease prevention solutions that have proved to be successful in the region.