Short-term response to a booster dose of hepatitis B vaccine in anti-HBs negative adolescents who had received primary vaccination 16 years ago

Hepatitis B surface antigen and antibody positivity among women of childbearing age after three decades of universal vaccination in South Korea

OBJECTIVES

We estimated the impact of universal hepatitis B immunization using 18-year data of women who are of childbearing age in South Korea.

METHODS

We used hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) data of 145,993 women aged 20-49 years during 2001-2018 at the Gangnam CHA Medical Center. Annual prevalences of HBsAg and anti-HBs positivity were calculated and tested for linear trend. We conducted age-period-cohort (APC) analysis to obtain period and cohort effect.

RESULTS

Overall proportion of HBsAg positivity was 3.5% (n = 5050) and anti-HBs positivity was 75.3% (n = 109,907) during the study period. HBsAg positivity percentage decreased from 5.1% in 2001 to 2.5% in 2018 (P < 0.001) while anti-HBs positivity increased from 59.9% to 75.8% (P = 0.002). Average annual percent change of HBsAg positivity was -5.9% (95% confidence interval (CI): -6.9%, -4.8%). The period and cohort RR curve identified a consistent decrease in HBsAg positivity over time and across generations.

CONCLUSIONS

We observed a concurrent decrease in HBsAg and an increase in anti-HBs seropositivity among Korean women of childbearing age, implicating success in preventing vertical transmission.

Evaluation of antibody persistence after a four-dose primary hepatitis B vaccination and anamnestic immune response in children under 6 years

Introduction. Tunisia is an intermediate hepatitis B virus (HBV) endemic country. The vaccination against hepatitis B was introduced in 1995 including four doses with a first dose administrated at birth. Decreasing the level of antibodies against hepatitis B surface antigen (anti-HBs) over time can be alarming. This study was conducted to explore the anti-HBV immune response among children under 6 years old, vaccinated according to the national vaccination schedule, by evaluating the immunological response to primary vaccination and by exploring the anamnestic immune response to a booster dose.Methods. We conducted a cross-sectional prospective study from June 2016 to June 2017 (n=180), based on voluntary participation. Children were recruited from the public pediatric ward sectors in Sahloul University Hospital of Sousse in Central Tunisia. An anti-HB titre was determined based on electro-chemiluminescence micro-particle immunoassay (ECLIA), using Elecsys Anti-HBs II kit, Roche.Results. Mean age at the time of enrollment in the study was 33±14.8 months. The seroprotection rate was 77.2 %. The anti-HB titre differed significantly between the different age groups (P=0.002). The predicting variable for having no seroprotective antibody level was older age. Children with anti-HB levels <10 IU l^{- 1} were offered an additional dose of HBV vaccine. Anamnestic response 1 month after the challenge dose was observed in 100 % of subjects. The probability of developing a high antibody response, following the booster dose increased in conjunction with an increased pre-booster antibody level.Conclusion. The response to a booster dose suggests the persistence of immune memory in almost all vaccinated individuals. Although a booster dose increases substantially anti-HB titre, the clinical relevance of such an increase remains unknown.

Maternal folic acid supplementation and antibody persistence 5 years after hepatitis B vaccination among infants

BACKGROUND

Maternal exposure to dietary factors during pregnancy may modulate the immunity of offspring by epigenetic programming. But the relationship between intrauterine environment and persistence of protective antibody after hepatitis B vaccination has not been reported. This study was to investigate the 5-year persistence of protective antibody response after primary hepatitis B vaccination, and its relationship with maternal folic acid supplementation.

MATERIALS AND METHODS

A total of 1461 children who completed a 3-dose 10 μg recombinant hepatitis B vaccine at birth and did not infect hepatitis B virus were followed up. Logistic regression and mediation analysis was used to explore the relationship between 5-year persistence of protective antibody and maternal nutrition.

RESULTS

Of 1403 children who did not revaccinated during the follow-up, 76.1% had protective hepatitis B surface antibody (anti-HBs) levels. Twenty percent of mothers did not take folate during pregnancy. Mediation analysis showed a total effect of folic acid supplementation on good persistence (odds ratio: 1.10, 95% CI: 1.03-1.17, p = 0.0010), a direct effect was 1.07 (95% CI: 1.01-1.13, p = 0.0128) and an indirect effect was 1.03 (95% CI: 1.00-1.06, p = 0.0672); the proportion of good persistence mediated by primary response was 30.3%.

CONCLUSION

This study indicated a good protective anti-HBs persistence at year 5 after 10 μg recombination hepatitis B vaccination in infants. Maternal folic acid supplementation may improve the persistence of protective antibodies through other pathways. Multi-center cohort studies should be conducted to verify this conclusion.

Changes and analysis of anti-HBs titres after primary immunization in 1- to 16-year-old Chinese children: A hospital-based study

Immunization with the hepatitis B vaccine is the most effective measure to prevent Hepatitis B Virus (HBV) infection. The aim of this study was to investigate the change in antibody levels induced by administration of the hepatitis B vaccine in children aged 1-16 year old in a large sample sized investigation. HBV markers were determined in 93 326 1- to 16-year-old hospitalized children who completed primary immunization as infants from south-west China, Chongqing. Analyses were performed on anti-HBs titre changes with increasing age, and the revaccination effect was evaluated in children aged 7-14. The percentage of protective antibody was between 45.29% and 63.33% in all age groups, but was higher in the 1-, 2- and 3-year-old groups (90.31%, 83.95% and 71.82%, respectively), and the rate of high-responder was 5.03%-10.56%, except in the 1-year-old group (23.33%). Additionally, 3.33%-25.79% of subjects had not seroconverted. There was no significant difference in antibody levels between girls and boys (P > .05). The Geometric Mean Titers in children with confirmed revaccination history were significantly higher than those with unknown or no revaccination history (P < .0001). In conclusion, the overall rate of protective anti-HBs was 67.10% with consecutive age groups from 1 to 16, it decreased from 90.31% to 45.29% for 1- to 8-year-old individuals, and interestingly, the rate increased from 45.46% to 63.33% for subjects aged 9-15. Anti-HBs titres were significantly improved after revaccination. Booster doses are recommended for those without seroconversion, especially children who live in school with other students or have family members with positive HBsAg.

Early and long term anamnestic response to HBV booster dose among fully vaccinated Egyptian children during infancy

OBJECTIVE

To evaluate early and long term anamnestic response to a booster dose of HBV vaccine among non-seroprotected children.

SUBJECTS AND METHOD

A national community based project was carried out on 3600 children aged 9 months to 16 years, fully vaccinated during infancy. They were recruited from 6 governorates representing Egypt. It revealed that 1535 children (42.8%) had non sero-protective anti-HBs (<10 IU/L) and were HBsAg or anti-HBc negative. A challenging dose of 10 μg of mono-valent Euvax HBV vaccine was given to 1121/1535 children. Quantitative assessment of anti-HBs was performed to detect early (2-4 weeks) and long term (one year) anamnestic responses.

RESULTS

Early anamnestic response developed among 967/1070 children (90.3%).Children having detectable anti-HBs (1-9 IU/L) significantly developed early anamnestic response (90%) compared to 85% with undetectable anti-HBs (<1 IU/L), P < 0.001. Multiple logistic analysis revealed that undetectable anti-HBs, living in rural residence and children aged 15-16 years were the most significant predicting risk factors for the absence of early anamnestic response (<10 IU/L), with AOR 2.7, 2.7 & 4.7 respectively. After one year, long term anamnestic response was absent among 15% of children who previously showed early response. Poor early anamnestic response and undetectable pre-booster anti-HBs were the significant predicting risk factors for absent long term anamnestic response, with AOR 18.7 & 2.7 respectively.

CONCLUSION

Immunological memory for HBV vaccine outlasts the presence of anti- HBs and HBV vaccination program provides effective long term protection even in children showing waning or undetectable concentrations of anti-HBs. This signifies no need for a booster dose especially to healthy children.

Hepatitis B Seroprotection and the Response to a Challenging Dose among Vaccinated Children in Red Sea Governorate

AIM:

To assess the long-term effectiveness of hepatitis B virus vaccine and the need for a booster dose among children who received three doses of vaccine during infancy in Red Sea Governorate.

METHODS:

A cross-sectional study was performed. Interviews with children (9 months to 16 years) and parents were done. Blood samples to assess Hepatitis B markers were tested. Children showing no seroprotection received a booster dose to assess their anamnestic response after four weeks and one year later.

RESULTS:

None of the participants had evidence of chronic Hepatitis B. The seroprotection rate was 23.3% and it significantly decreased with age. Multivariate logistic analysis revealed that older age was the significant predicting variable for having no seroprotective level, while baseline anti-HBs level < 3.3 IU/L was the predicting variable for not developing early anamnestic response or loss of late anamnestic response.

CONCLUSION:

Long-term immunity persists among children who received complete series of hepatitis B vaccination during infancy even in absence or reduction of anti-HBs over time. Therefore, a booster dose is not necessary to maintain immunity till the age of sixteen.

Age-dependent decrease of anti-HBs titers and effect of booster doses using 2 different vaccines in Palestinian children vaccinated in early childhood

Immunization against hepatitis B virus (HBV) has proven to be highly effective and led to significant reduction of new infections worldwide. However, protective immunity measured by anti-HBs titers may decrease to critical levels in the years after basal immunization, particularly in case of exposure to HBV variants different from the vaccine strain. We tested 400 Palestinian children between one and 19 years of age for their anti-HBs titer, challenged the immune memory of those with low or absent anti-HBs with 2 types of hepatitis B vaccines and determined thereafter the anti-HBs titer. At the age of one, 92.2% of the children presented with protective anti-HBs titers (≥ 10 mIU/ml) with the majority having ≥ 100 mIU/ml. Protective immunity was still high at ages 2 (87.5%) and 4 (95%), declining by age 5 and 6 (from 69.2% to 66.7%) and down to an average of 39.8% between the ages of 7 and 19. 160 children with a nonprotective or low immune response challenged with either the yeast-derived Engerix-B or the mammalian cell-derived preS1-containing Sci-B-Vac vaccine showed an anamnestic immune response. 92.4% and 85.9% of the children challenged with one dose Sci-B-Vac and Engerix-B presented with anti-HBs titers >100 mIU/ml respectively. Our results reveal that vaccine-induced protective anti-HBs titers against HBV decrease rapidly beyond the age of 6 in Palestinian children, but can be strongly enhanced with a single booster vaccine dose, independent of brand and antigen composition. Our data suggest that a booster vaccine dose against HBV during school years may be useful.

Response to booster doses of hepatitis B vaccine among young adults who had received neonatal vaccination

Background

Newborns who have received hepatitis B immunization in 1980s are now young adults joining healthcare disciplines. The need for booster, pre- and post-booster checks becomes a practical question.

Aims

The aim of this study is to refine the HBV vaccination policy for newly admitted students in the future.

Methods

A prospective study on medical and nursing school entrants to evaluate hepatitis B serostatus and the response to booster doses among young adults.

Findings

Among 212 students, 17–23-year-old, born after adoption of neonatal immunization, 2 (0.9%) were HBsAg positive, 40 (18.9%) were anti-HBs positive. At 1 month after a single-dose booster for anti-HBs-negative students, 14.5% had anti-HBs <10 mIU/mL, 29.0% and 56.5% were 10–100 and >100 mIU/mL, respectively. The anti-HBs levels were significantly higher for females than males (mean [SD]: 431 [418] vs. 246 [339] mIU/mL, P = 0.047). At 2–4 month after the third booster dose, 97.1% had anti-HBs >100 mIU/mL and 2.9% had 10–100 mIU/mL.

Conclusions

Pre-booster check is still worthwhile to identify carriers among newly recruited healthcare workers born after adoption of neonatal immunization. A 3-dose booster, rather than a single dose, is required for the majority to achieve an anti-HBs level >100 mIU/mL, as memory immunity has declined in a substantial proportion of individuals. Cost-effectiveness of post-booster check for anti-HBs is low and should be further evaluated based on contextual specific utilization of results.

Seroprevalence of hepatitis B and immune response to hepatitis B vaccination in Chinese college students mainly from the rural areas of western China and born before HBV vaccination integrated into expanded program of immunization

The prevalence of hepatitis B surface antigen (HBsAg) in a population aged 15 y or older was high in China, but an immunization strategy for this population was unavailable. We investigated the seroprevalence of hepatitis B and immune response to HBV vaccine in Chinese college students (n=2040 participants), 11.1%, 80.8%, and 8.1% had confirmed, unknown and no HBV vaccination history, respectively. The seropositive rates for HBsAg, anti-HBs sole and anti-HBs plus anti-HBc were 12.6%, 25.7%, and 30.1%, respectively. The HBsAg seropositive rate was significantly lower in participants with confirmed HBV vaccination history than in those with unknown or no vaccination history (5.3%, 13.6%, and 12.6%, respectively, P=0.0019). The anti-HBs alone seropositive rate was significantly higher in participants with confirmed HBV vaccination history than in those with unknown or no vaccination history (37.6%, 25.3%, and 13.8%, respectively, P<0.0001). Participants negative for HBsAg, anti-HBs, and anti-HBc at baseline (n=600) were given three doses of recombinant HBV vaccine (GlaxoSmithKline) at month 0, 1, and 6. Robust immune response was elicited after two and three doses (seroprotective rate: 91.9% and 99.0%, respectively, and geometric mean concentration [GMC]: 95.8 and 742.6 IU/L, respectively). Fourteen months after the third dose, the anti-HBs seroprotective rate of the group remained more than 97%. The seroprotective rates and GMCs did not differ significantly by vaccination history. This study suggested that three doses of 20 μg HBV vaccine were needed for college students negative for HBsAg, anti-HBs, and anti-HBc to ensure high seroprotective rates and concentrations.

Determinants of Long-term protection after hepatitis B vaccination in infancy: a meta-analysis

BACKGROUND

The duration of protection after hepatitis B vaccination in early infancy is unclear and may be related to vaccination schedule, dosage, vaccine type and population characteristics. Factors potentially influencing waning immunity were assessed.

METHODS

A systematic review was performed. The main outcomes were prevalence of anti-hepatits B antibodies ≥ 10 mIU/mL after primary or booster vaccination. Factors potentially influencing protection were assessed in an adjusted random-effects meta-analysis model by age for both outcomes. Results of both meta-analyses were combined in a prognostic model.

RESULTS

Forty-six studies reporting on the anti-hepatits B antibodies ≥ 10 mIU/mL 5 to 20 years after primary immunization and 29 on booster response were identified. The adjusted meta-analyses identified maternal carrier status (odds ratio [OR]: 2.37 [1.11; 5.08]), lower vaccine dosage than presently recommended (OR: 0.14 [0.06; 0.30]) and gap time between last and preceding dose of the primary vaccine series (OR: 0.44 [0.22; 0.86]) as determinants for persistence of anti-hepatits B antibodies ≥ 10. A lower vaccine dosage was also associated with failure to respond to booster (OR: 0.20 [0.10; 0.38]). The prognostic model predicted long-term protection of 90% [77%; 100%] at the age of 17 years for offspring of noncarrier mothers vaccinated with a presently recommended dose and vaccination schedule.

CONCLUSIONS

Based on meta-analyses, predictors of waning immunity after hepatitis B vaccination in infancy could be identified. A prognostic model for long-term protection after hepatitis B vaccination in infancy was developed.

The effects of booster vaccination on hepatitis B vaccine in anti-HBs negative infants of HBsAg-positive mothers after primary vaccination

The purpose of this study was to investigate the changes in anti-HBs IgG levels after booster vaccinations in anti-HBs negative infants of HBsAg-positive mothers. After primary vaccination, the immunization effects of different dosages of booster vaccinations of hepatitis B vaccine (CHO) were compared. A group of 472 newborns were vaccinated with three-dose hepatitis B vaccine at birth, 1 mo and 6 mo of age. Blood serum was collected within 6-12 mo after the third dose, and HBsAg, anti-HBs and anti-HBc levels were determined. Of this group, 101 infants who were both anti-HBs and HBsAg negative were revaccinated with 20 μg hepatitis B vaccine (CHO), and their antibody titers were monitored. Among these 101 infants, the anti- HBs positive rates (defined as anti-HBs ≥ 100 mIU/ml) differed after the first and the third dose (79% and 90%, respectively (p<0.05), while differences in the corresponding geometric mean titers (GMTs) were not statistically significant (629 ± 3 mIU/ml and 572 ± 3 mIU/ml respectively, p<0.05). The anti-HBs GMTs after booster vaccination were 10-fold larger than those before booster vaccination. We conclude that a single booster dose is generally adequate for infants of HBsAg-positive mothers, whereas a further booster dose should be given for non-responders.

The effects of booster vaccination on combined hepatitis A and hepatitis B vaccine in both anti-HBs and anti-HAV negative children 5-15 years after hepatitis B vaccine primary immunization

In the present study, we investigated the changes in both anti-HAV lgG and anti-HBs lgG levels and compared the antibody seroconversion rates of different doses of combined hepatitis A and hepatitis B vaccine in children. Children who were vaccinated as infants with Hepatitis B vaccine were revaccinated at 5-15 y of age, then the antibody titers were monitored. Among 283 children, this study found that the anti-HAV seroconversion rates (defined as anti-HAV ≥ 1 mIU/ml) after the first and the third dose were 79.9% and 100% respectively; these observed differences were statistically significant (P<0.05); the corresponding geometric mean titers (GMTs) were 4.72 ± 2.63 mIU/ml and 13.46 ± 1.16 mIU/ml respectively. The anti-HBs seroconversion rates (defined as an anti-HBs ≥ 10 mIU/ml) were 82.3% and 99.0% respectively; these observed differences were statistically significant (P<0.05); and the corresponding titers were 319.95 ± 5.16 mIU/ml and 418.59 ± 3.89 mIU/ml respectively. After the first booster dose, the difference in anti-HAV seroconversion rate was statistically significant in children aged 5-9 y and 10-15 y (P<0.05), as was the difference of anti-HBs seroconversion, whereas after the third dose the difference was not statistically significant (P>0.05). This study demonstrated that the immunization effects of booster vaccination with combined hepatitis A and hepatitis B vaccine is successful for children. A single booster dose is adequate for younger children, while three doses are needed for older children.

Chronic hepatitis B infection in adolescents who received primary infantile vaccination

Hepatitis B virus (HBV) infection is a global health issue. Universal infantile hepatitis B (HB) vaccination is very efficacious. However, HBV infections among those immunized subjects have been reported. The long-term efficacy of postnatal passive-active HB vaccination in high-risk subjects is not well explored. A total of 8,733 senior high school students who were born after July 1987 were assayed for hepatitis B surface antigen (HBsAg) and antibodies to HBsAg (anti-HBs). The overall HBsAg and anti-HBs-positive rates were 1.9% and 48.3%, respectively. The HBsAg-positive rate was 15% in HB immunoglobulin (HBIG) recipients (adjusted odds ratio [OR]: 15.63; 95% confidence interval [CI]: 10.99-22.22). Among students who did not receive HBIG, there was a significantly negative association between HB vaccination dosage and HBsAg-positive rate (P for trend = 0.011). Adjusted ORs for those who received 4, 3, and 1 to 2 doses were 1.00, 1.52 (95% CI: 0.91-2.53), and 2.85 (95% CI: 1.39-5.81), respectively. Among HBIG recipients, the HBsAg-positive rate was significantly higher in subjects with maternal hepatitis B e antigen (HBeAg) positivity and who received HBIG off-schedule. A booster dose of HB vaccination was administered to 1974 HBsAg- and anti-HBs-negative subjects. Prebooster and a postbooster blood samples were drawn for anti-HBs quantification. The proportions of postbooster anti-HBs titer <10 mIU/mL was 27.9%. Subjects with prebooster anti-HBs titers of 1.0-9.9 mIU/mL had significantly higher postbooster anti-HBs titers than those with prebooster anti-HBs titers of <1.0 mIU/mL (P < 0.0001).

CONCLUSION

Having maternal HBeAg positivity is the most important determinant for HBsAg positivity in adolescents who received postnatal passive-active HB vaccination 15 years before. A significant proportion of complete vaccinees may have lost their immunological memories against HBsAg.

Waning immunity and booster responses in nursing and medical technology students who had received plasma-derived or recombinant hepatitis B vaccine during infancy

BACKGROUND

The national hepatitis B virus (HBV) vaccination program was launched in Taiwan in 1984. After November 1992, a recombinant HBV vaccine replaced the plasma-derived HBV vaccine.

METHODS

A total of 1,812 nursing and medical technology freshman students was tested to evaluate their waning immunity toward hepatitis B. In the 2007 (2008) academic year, 438 (382) students testing nonprotective antibodies received 3 (1) booster doses of HBV vaccine according to suggestions from Taiwan's Center for Disease Control (CDC).

RESULTS

The seroprevalences of hepatitis B surface antigen (+) were 0.8% and 0.7% in the plasma-derived and recombinant group, respectively; for antibody to hepatitis B surface antigen (anti-HBs) (+), they were 43.2% and 33.3% (P < .001), respectively. In the 2007 freshman group, 99.1% of the students previously vaccinated with plasma-derived HBV vaccine exhibited anti-HBs seroconversion. In the 2008 freshman group, the booster dose induced anti-HBs seroconversions of 92.1% and 95.9% in the students who had received the plasma-derived and recombinant HBV vaccine, respectively (P = .370).

CONCLUSION

Most students exhibited signs of immune memory after receiving the booster, regardless of having received plasma-derived or recombinant HBV. Only a small number of vaccinees lost their immune memory after 16 years, suggesting that some students might benefit from boosting before proceeding to clinical practice.

Booster dose vaccination for preventing hepatitis B

BACKGROUND

Antibodies against hepatitis B surface antigen (HBs) wane over time after vaccination for hepatitis B (HB); hence, the duration of protection provided by the vaccine is still unknown but may be evaluated indirectly by measuring the anamnestic immune response to booster doses of vaccine.

OBJECTIVES

To assess the benefits and harms of booster dose hepatitis B vaccination for preventing HB infection.

SEARCH STRATEGY

We searched The Cochrane Hepato-biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 4, 2010) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, conference databases, and reference lists of articles to May 2010. We also contacted authors of articles and manufacturers.

SELECTION CRITERIA

Randomised clinical trials addressing anamnestic immune response to booster of HB vaccine five years or more after primary vaccination in apparently healthy participants, vaccinated in a 3-dose or 4-dose schedules of HB vaccine without receiving additional dose or immunoglobulin.

DATA COLLECTION AND ANALYSIS

Two authors made the decisions if the identified publications on studies met the inclusion criteria or not. Primary outcome measures included the proportion with anamnestic immune response in non-protected participants and signs of hepatitis B virus infection. Secondary outcomes were the proportion with local and systemic adverse event events developed following booster dose injection. Weighted proportion were planned to be reported with 95% confidence intervals.

MAIN RESULTS

There were no eligible randomised clinical trials fulfilling the inclusion criteria of this review.

AUTHORS' CONCLUSIONS

We were unable to identify randomised clinical trials on the topic. We need randomised clinical trials to formulate future booster policies for preventing hepatitis B infection.

Hepatitis B vaccination strategies tailored to different endemicity levels: some considerations

Hepatitis B is a serious public health problem. Worldwide three different levels of hepatitis B endemicity (high, intermediate and low) can be distinguished. Areas with different levels of endemicity require tailored vaccination strategies to fit the needs for individuals at risk and/or countries, depending on the infection risk per age group, vaccination rate, duration of protection after vaccination, cost effectiveness of vaccination strategies and ease of implementation in the national immunization schedules.This opinion paper evaluates these factors and proposes a combination of infant risk group and universal adolescent vaccination for low endemic countries thus targeting the different groups at risk. A universal infant vaccination schedule starting with a newborn vaccination within 24h after birth is more appropriate in intermediate- and high-endemic regions.

Persistence of antibodies and immune memory to hepatitis B vaccine 20 years after infant vaccination in Thailand

Booster vaccination against hepatitis B (HBV) is not currently recommended, although debate continues on the duration of protection after priming. We assessed antibody persistence and immune memory to hepatitis B 20 years after priming with a recombinant HBV-vaccine during infancy. Infants were vaccinated at birth, 1, 2 and 12 months of age. A subset received a booster dose at Year 5. Antibody persistence was measured approximately yearly until Year 20. Immune memory was assessed by administration of HBV booster dose. At Year 20, anti-HBs seroprotection rates and GMCs tended to be higher in Year 5 boosted than unboosted recipients (83.9% versus 60.5%). After the Year 20 booster dose, anti-HBs anamnestic responses were within the same range 95.8% of subjects in both groups. Primary and booster vaccination with HBV-vaccine in infants induces sustained seroprotection and immune memory against hepatitis B for up to 20 years. Higher persisting seroprotection rates in subjects boosted at Year 5 did not translate into apparent differences in immune memory in a high endemic country.

Long-term immunogenicity of preservative-free hepatitis B vaccine formulations in adults

Vaccination with recombinant hepatitis B vaccines is highly effective in preventing hepatitis B infection. Recently, a preservative-free (PF) formulation of hepatitis B vaccine [GlaxoSmithKline (GSK) Biologicals, Rixensart, Belgium] has been licensed. The immunogenicity of the PF hepatitis B vaccine and antibody persistence 6 years later was assessed in this study. This formulation was compared with the preservative- containing (PC) formulation of the vaccine and a low-preservative (LP) content formulation. Five hundred forty-one healthy adult subjects were evaluated in the primary study. Over 94% of the subjects in the three study groups had seroprotective anti-HBs antibody concentrations (>or=10 mIU/ml) 1 month after completing primary vaccination. Antibody measurements in 242 healthy adults who returned for the follow-up study and who had received primary vaccination 6 years earlier showed that over 81% of subjects in the three study groups still had anti-HBs antibody concentrations >or=10 mIU/ml. No apparent differences in antibody decline or distribution between the study groups were observed. These results indicate that the removal of preservatives from the hepatitis B vaccine does not affect adversely its immunogenicity both in the short and in the longer term.

Hepatitis B immunity in adolescents and necessity for boost vaccination: 23 years after nationwide hepatitis B virus vaccination program in Taiwan

The first universal hepatitis B vaccination program for newborns in the world was launched in Taiwan in July 1984. Most studies on the effectiveness of hepatitis B vaccination focused on the seroprevalence of HBs Ag among children under 14 years old. Only few studies focused on the seropositivity of anti-HBs among adolescents aged 15-18 years old. The present study aimed to evaluate the impact of the nationwide hepatitis B vaccination program on the immunity to HBV infection and the necessity of boost among adolescents. In this study including eight annual seroprevalence surveys from 2000 to 2007, 2342 college entrants (1589 15-year-olds in group I and 753 18-year-olds in group II) and 1851 university freshmen (18-year-olds in group III) participated. Subjects identified anti-HBs, HBs Ag and anti-HBc negative were given boost three doses of HBV vaccine. The HBs Ag seroprevalence was 11.6%, 3.5% and 1.0% for participants who were born before 1984, 1984-1986 and after 1986. The anti-HBs-seropositive rates were significantly higher in group II (83.1%) than in group I (53.0%) and group III (53.5%). All 572 participants who were seronegative for anti-HBs, HBs Ag and anti-HBc became anti-HBs-seropositive after catch-up vaccination. It is concluded that the anti-HBs-seropositive rate decreased to 50% in 15 years after vaccination, and boost vaccination was 100% effective. The necessity and age for boost among anti-HBs negative adolescents and the timing of the first immunization should be further evaluated.

HLA and response to booster hepatitis B vaccination in anti-HBs-seronegative adolescents who had received primary infantile vaccination

To explore contemporarily genetic and non-genetic determinants of long-term immunological memory to hepatitis B (HB) vaccination, we conducted a case-control study nested in an adolescent cohort of booster recipients who had received primary infantile HB vaccination but with residual anti-HBs titers <10 mIU/mL at 15-18 years of age. High-resolution phenotypes of human leukocyte antigen (HLA)-A, -B, and -DRB1 loci were determined by sequence-specific oligonucleotide probe hybridization. After controlling for pre-booster anti-HBs levels, the absences of HLA-A*02 and -DRB1*08, simply expressed as A*02(-) and -DRB1*08(-), and the presence of B*15 were significantly associated with elevated risks of non-response (post-booster anti-HBs titers<10 mIU/mL) to booster vaccination. The adjusted odds ratios (ORs) were 3.85 (CI, 1.82-8.33), 4.55 (CI, 1.23-16.67), 3.59 (CI, 1.40-9.17), respectively. There was multiplicative synergism between A*02 and B*15 on the risk of non-response to booster vaccination. The multivariate-adjusted ORs for A*02(-)/B*15, A*02(-)/B*15(-), A*02/B*15, and A*02/B*15(-) haplotypes were 20.39 (p=0.0003), 3.29 (p=0.007), 1.32 (p>0.05), and 1.0, respectively. Recent cigarette smoking and/or betel-quid chewing was associated with a 12-fold risk of non-response to booster vaccination. Further comparisons between responders and adolescents who had undetectable post-booster anti-HBs titers (<0.1 mIU/mL) demonstrated similar results. Our results indicated that response to booster HB vaccination as well as long-term immunological responses to HB vaccination are closely related with host genetic factors, and probably modified by recent substance use.