Is booster injection with hepatitis B vaccine necessary in healthy responders? A study of the immune response

Chronic Viral Hepatitis in Elite Athletes: Approaches to Risk Assessment, Prevention and Management

Elite athletes who participate in contact sports are at risk of bleeding injuries, leading to transmission of blood-borne viruses including hepatitis type B, C and D (HBV, HCV and HDV) capable of causing chronic liver disease, liver failure and liver cancer. In view of the significant advances in the viral hepatitis field over the past decade, more structured approaches should be in place to screen for and manage viral hepatitis in elite athletes. HBV status should be assessed in all elite athletes, and those infected should receive nucleos(t)ide analogues for viral suppression, while uninfected individuals should receive HBV vaccination. The all-oral direct acting antivirals for HCV are highly effective and safe, thus the remaining challenge with hepatitis C is case identification and linkage to care. HDV is only found in HBV-infected individuals, which is characterized by rapid disease progression and higher rates of cirrhosis and liver cancer in infected subjects. Pegylated interferon was the mainstay of treatment for HDV infection until bulevirtide, a viral entry inhibitor, was recently approved by the European Union (EMA) and FDA in America, while multiple novel therapies are already in clinical trials as part of the HBV cure program. Overall, awareness of chronic viral hepatitis in athletes should be improved. Prevention remains the cornerstone of the management of viral hepatitis in sport coupled with rigorous disease assessment in infected individuals, and antiviral therapy where indicated.

Prevalence of Undetectable Vaccine-Induced Immunity Against Hepatitis B Virus in US Adults at High Risk for Infection

In 2015, the Centers for Disease Control and Prevention reported a substantial increase in the number of acute hepatitis B virus (HBV) infections in the United States. Although national guidelines recommend vaccination of adults at high risk for HBV infection, the prevalence of undetectable immunity (i.e., susceptibility) in this population remains unknown. In this study, we analyzed a nationally representative sample using the National Health and Nutrition Examination Survey to evaluate the prevalence, trend, and predictors of undetectable vaccine-induced antibodies against HBV surface antigen (<10 mIU/mL) among high-risk adults from 2003-2014. Among adults at high risk for HBV infection, the prevalence of undetectable immunity decreased from 83.2% in 2003-2004 (95% confidence interval [CI]: 81.3-85.0) to 69.4% (about 64 million) in 2013-2014 (95% CI: 66.0-72.6). The prevalence decreased significantly in individuals with multiple sex partners or sexually transmitted disease and in pregnant women. However, there were no significant changes in men who have sex with men (MSMs), intravenous drug users (IDUs), hepatitis C virus (HCV)-infected and patients with diabetes, and those with elevated aspartate aminotransferase/alanine aminotransferase (AST/ALT). Mexican Americans had the highest prevalence of undetectable immunity (77.6%, 95% CI: 72.6-81.9), followed by non-Hispanic whites (70.1%, 95% CI: 66.9-73.1). Older age, lower socioeconomic status, and having at least 1 high-risk factor were associated with a higher risk of undetectable immunity, whereas an increased risk among the foreign-born disappeared after multivariable adjustment. Conclusion: Approximately 64 million high-risk adults in the United States remain susceptible to HBV infection, especially MSMs, IDUs, diabetics, HCV patients, and populations with elevated AST/ALT. To eliminate HBV, efforts should be made to increase screening and vaccination in high-risk adults.

Characteristics of memory B cells elicited by a highly efficacious HPV vaccine in subjects with no pre-existing immunity

Licensed human papillomavirus (HPV) vaccines provide near complete protection against the types of HPV that most commonly cause anogenital and oropharyngeal cancers (HPV 16 and 18) when administered to individuals naive to these types. These vaccines, like most other prophylactic vaccines, appear to protect by generating antibodies. However, almost nothing is known about the immunological memory that forms following HPV vaccination, which is required for long-term immunity. Here, we have identified and isolated HPV 16-specific memory B cells from female adolescents and young women who received the quadrivalent HPV vaccine in the absence of pre-existing immunity, using fluorescently conjugated HPV 16 pseudoviruses to label antigen receptors on the surface of memory B cells. Antibodies cloned and expressed from these singly sorted HPV 16-pseudovirus labeled memory B cells were predominantly IgG (>IgA>IgM), utilized diverse variable genes, and potently neutralized HPV 16 pseudoviruses in vitro despite possessing only average levels of somatic mutation. These findings suggest that the quadrivalent HPV vaccine provides an excellent model for studying the development of B cell memory; and, in the context of what is known about memory B cells elicited by influenza vaccination/infection, HIV-1 infection, or tetanus toxoid vaccination, indicates that extensive somatic hypermutation is not required to achieve potent vaccine-specific neutralizing antibody responses.

There is an urgent need to better understand how to reliably generate effective vaccines, particularly subunit vaccines, as certain pathogens are considered to pose too great of a safety risk to be developed as live, attenuated or killed vaccines (e.g., HIV-1). The human papillomavirus (HPV) vaccines are two of the most effective subunit vaccines ever developed and have continued to show protection against HPV associated disease up to and beyond five years post-vaccination. Moreover, the target population for these vaccines have essentially no pre-existing immunity to the HPV types covered by the vaccine; therefore, these vaccines provide an excellent model for studying the immunity elicited by a highly effective subunit vaccine. As the HPV vaccines, like most vaccines, protect by generating antibodies, we are interested in characterizing the memory B cells elicited by the HPV vaccine. Memory B cells help to sustain antibody levels over time by rapidly differentiating into antibody secreting cells upon pathogen re-exposure. Although previous studies have provided evidence that the HPV vaccines elicit memory B cells, they did not characterize these cells. Here, we have isolated HPV-specific memory B cells from adolescent females and women who received the quadrivalent HPV vaccine and have cloned antibodies from these cells. Importantly, we find that these antibodies potently inhibit HPV and that the memory B cells from which they derive exhibit hallmarks of long-lived memory B cells.

Strategies to increase responsiveness to hepatitis B vaccination in adults with HIV-1

HIV and hepatitis B virus co-infection leads to substantially increased morbidity and mortality compared with either infection alone. Immunisation with hepatitis B virus vaccine is the most effective way to prevent the infection in people with HIV; however, these patients have decreased vaccine responses and a short duration of protection compared with immunocompetent individuals. Control of HIV replication with highly active antiretroviral therapy and increased CD4 cell counts are associated with improved immune responses to hepatitis B vaccination. New vaccination strategies, such as increased vaccine dose, use of the intradermal route, and addition of adjuvants, could improve response rates in adults with HIV.

Hepatitis B vaccine in celiac disease: Yesterday, today and tomorrow

Some studies showed that in celiac patients the immunological response to vaccination is similar to that one found in general population except for vaccine against hepatitis B virus (HBV). The non-responsiveness to HBV vaccine has also been described in healthy people, nevertheless the number of non-responders has been demonstrated to be higher in celiac disease (CD) patients than in healthy controls. Several hypothesis explaining this higher rate of unresponsiveness to HBV vaccine in CD patients have been described, such as the genetic hypothesis, according with CD patients carrying the disease-specific haplotype HLA-B8, DR3, and DQ2, show a lower response to HBV vaccine both in clinical expressed CD patients and in healthy people carrying the same haplotype. On the other hand, it has been demonstrated that the gluten intake during the vaccination seems to influence the response to the same vaccine. Moreover, it has been demonstrated a possible genetic predisposition to hepatitis B vaccine non-responsiveness likely due to the presence of specific human leukocyte antigen haplotypes and specific single nucleotide polymorphism in genes of cytokine/cytokine receptors and toll like receptors, but the pathogenic mechanism responsible for this low responsiveness still remains unclear. The aim of this review is to focus on the possible pathogenic causes of unresponsiveness to HBV vaccine in CD patients and to propose an alternative vaccination schedule in order to improve the responsiveness to HBV vaccine in this at-risk patients.

Seroconversion by EMS Personnel Vaccinated with HBV Recombinant DNA

Objective:

To evaluate the seroconversion rate of EMS personnel given the hepatitis B virus (HBV) recombinant deoxyribonucleic acid (DNA) vaccine series.

Design:

Retrospective review of paramedics and firefighters consecutively completing the HBV recombinant DNA vaccine program.

Setting:

Urban, non-prof it, private, regional EMS Resource Hospital. The Chicago North EMS System is under contract with the Chicago Fire Department. This contract allows for the voluntary vaccination of EMS personnel with recombinant DNA-HBV vaccine and treatment and follow-up of paramedics and firefighters possibly exposed to HBV.

Population:

Initial 68 EMS personnel completing HBV recombinant DNA vaccine program (48 primary prophylaxis and 20 post-exposure prophylaxis).

Intervention:

HBV recombinant DNA vaccine series was administered voluntarily to Chicago EMS System paramedics and firefighters per manufacturers recommendations. Two weeks after completion of the vaccination series, blood samples for HBV antibody titres were drawn to determine reactivity and the need for further immunization.

Results:

Of the 68 vaccinated individuals, only two had negative titres (3%). These two individuals were given a fourth dose of vaccine with successful seroconversion.

Conclusions:

Prehospital care personnel are known highrisk, health-care workers for acquiring HBV and should be vaccinated prophylactically. There is a high seroconversion rate (97%) utilizing HBV recombinant DNA vaccine. However, post-vaccination antibody titres must be performed to identify those rare individuals that do not seroconvert.

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 seroprevalence and anamnestic response amongst Taiwanese young adults with full vaccination in infancy, 20 years subsequent to national hepatitis B vaccination

The long-term protective effect of hepatitis B virus (HB) vaccination against HB infection and the necessity for routine booster vaccination in young-adult age subsequent to full HB immunization at birth remain issues of some debate currently. This study is aimed at evaluating the seroprevalence of HB infection and the response to HB booster vaccination amongst young-adult university students who had previously undergone full vaccination during their infancy. Eight hundred and forty-three subjects (mean age 18.7+/-0.4 years), 492 males and 351 females, with a complete HB vaccination during infancy were enrolled into this study. The prevalence of natural HB infection, chronic HB-carrier status, and HB-naïve group was, respectively, 4.1%, 1.4%, and 62.3%. Amongst 316 study subjects who were naïve to HB infection and had received one HB booster at time of university entrance health examination, 49.6%, 91.4%, and 97.5% of the participants with a serum anti-HBs level <0.1, 0.1 to <1.0 and 1.0 to <10.0mIU/mL prior to the booster vaccination, respectively, developed an anamnestic response (i.e., >/=10mIU/mL) to a booster dose of HB vaccine. Full implementation of national-wide HB vaccination program in 1986 has significantly reduced the incidence of HB infection and associated carrier rate in Taiwan. Approximately three-quarter of the subjects who were naïve to HB infection and had received one HB booster demonstrated an anamnestic response to a booster HB vaccine. The higher the anti-HBs titers remained for an individual subsequent to primary vaccination, the greater the anamnestic response observed. Additional long-term follow-up studies are needed for young adults initially vaccinated for HB in their infancy.

Ten-year persistence of antibody to hepatitis B surface antigen in healthcare workers vaccinated against hepatitis B virus, and response to booster vaccination

This study estimated the number of HCWs with protective antibody levels 5 and 10 years after HBV vaccination. Kaplan-Meier probabilities of protective levels were 0.95 at 60 days after vaccination, 0.87 at 5 years, and 0.79 at 10 years. Those without protective levels displayed good response 7 and 30 days after a booster.

Long-term persistence of T cell memory to HBsAg after hepatitis B vaccination

AIM

To determine if the T cell memory to HBsAg can persist for a long time after hepatitis B (HB) vaccination.

METHODS

Thirty one vaccine recipients who were healthcare workers (18 females and 13 males aged 34-58 years) from Utrecht University Hospital, Netherlands, and had previously received a standard course of vaccination for hepatitis B were investigated and another 9 unvaccinated healthy volunteers from the same hospital were used as the control. Blood samples were taken just before the experiment to test serum anti-HBs levels and the subjects were classified into different groups according to their serum titers of anti-HBs and vaccination history. Their peripheral blood mononuclear cells (PBMC) were isolated from freshly heparinized venous blood and the proliferative response of T lymphocytes to the recombinant hepatitis B surface antigen (HBsAg) was investigated.

RESULTS

Positive serum anti-HBs was found in 61.3% (19/31) vaccine recipients and a significant in vitro lymphocyte proliferative response to recombinant HBsAg was observed in all the vaccinees with positive anti-HBs. Serum anti-HBs level < or =10 IU/L was found in 38.7% (12/31) subjects. In this study, we specially focused on lymphocyte proliferative response to recombinant HBsAg in those vaccine recipients with serum anti-HBsAg less than 10 IU/L. Most of them had received a standard course of vaccination about 10 years before. T lymphocyte proliferative response was found positive in 7 of the 12 vaccine recipients. These results confirmed that HBsAg-specific memory T cells remained detectable in the circulation for a long time after vaccination, even when serum anti-HBs level had been undetectable.

CONCLUSION

The T cell memory to HBsAg can persist for at least 10 years after HB vaccination. Further booster injection is not necessary in healthy responders to HB vaccine.

Is a low dose of hepatitis B vaccine enough for a rapid vaccination scheme?

AIM: To determine whether or not a low dose of HB vaccine can be effectively used in the rapid vaccination.

METHODS: Rapid vaccination (0, 1, 2 months) with low dose (5 μg) or routine dose (10 μg) HB vaccine was studied in 250 subjects (130 school children and 120 university students). Serum from all the participants was tested for HBsAg, anti-HBs and anti-HBc at 1, 3 and 7 months after the first dose of vaccination and all subjects were serum HBV marks negative before the vaccination. Non-responders to a complete initial vaccination from university students were given an additional vaccination with 10 μg of HB vaccine and their serum anti-HBs was tested again one month later.

RESULTS: One month after the third dose of vaccination (third month) sero-conversion rates and geometric mean titer (GMTs) were significantly (P < 0.01) higher in the routine dose (resp. 89% and 106.8) than in the low dose group (resp. 72% and 59.5). Sero-conversion rates and GMTs were maintained stable for another 4 months in both groups. After an additional vaccination to non-responders with 10 μg HB vaccine, 17/23 subjects (13/15 from those vaccinated with 5 μg vaccine and 4/8 from those vaccinated with 10 μg vaccine) became anti-HBs positive, yielding similar sero-conversion rates for both dose groups.

CONCLUSION: Higher sero-conversion rates and GMTs were reached in those vaccinated with 10 μg HB vaccine than in those vaccinated with 5 μg HB vaccine after a complete vaccination with a 0, 1, 2 month scheme. But the subjects vaccinated with 5 μg vaccine can also reach the similar sero-conversion rate after an additional vaccination.

Long term antibody response to hepatitis B vaccination beginning at birth and to subsequent booster vaccination

BACKGROUND

Few studies have examined the long term persistence of antibody after hepatitis B immunization beginning at birth and the response to a subsequent challenge with a booster dose of vaccine.

METHODS

Two groups of children received hepatitis B vaccine on a schedule of birth and 1 and 6 months of age. Group 1 received recombinant vaccine and a booster dose at 5 years of age. Group 2 received plasma-derived vaccine and a booster dose at 9 years of age. Group 1 children were tested for antibody after the primary vaccine series. All children were tested for antibody before administration of the booster dose and at 2 and 4 weeks and 1 year after the booster. In addition all children were tested for markers of hepatitis B virus infection.

RESULTS

Antibody testing conducted after the primary series for children in Group 1 (n = 70) showed that 90% had protective antibody concentrations at 13 months of age, and testing before the booster dose showed that 41% had protective antibody concentrations. All children with protective antibody concentrations after the primary series had an anamnestic antibody response to the booster dose. In Group 2 (n = 41) 39% of children had protective antibody concentrations before the booster dose, and 93% had an anamnestic antibody response to the booster dose. One year after the booster dose there were 26-fold and 11-fold declines in antibody concentration in Groups 1 and 2, respectively.

CONCLUSIONS

A primary vaccination series with either plasma-derived or recombinant hepatitis B vaccine affords long term protection for children when vaccinated beginning soon after birth.

Are we giving too many doses of hepatitis A and B vaccines?

The immune response of an inactivated hepatitis A vaccine given to middle aged travellers 4-6 years after one single, primary dose was recently studied. All 25 vaccinees showed an impressive anamnestic booster response (GMT 2.993mIU/ml). The study confirms one previous report as well as experimental data, indicating a long-term proliferative T-cell response following one single primary dose of Havrix 1440. In 1999, Wiström et al. demonstrated that a booster 4 years after priming medical students with one single dose of a recombinant HB vaccine disclosed a rapid antibody response indicating a well-preserved memory. These reports put in focus the question: are we routinely offering too many doses of hepatitis A and B vaccines?

Prevention of hepatitis B infections: vaccination and its limitations

Infection with hepatitis B virus has become a vaccine-preventable disease. The recombinant hepatitis B vaccines available today are safe and immunogenic. In order for these vaccines to eradicate HBV a universal vaccination of neonates and/or children needs to be implemented. Major obstacles on the road to global hepatitis B vaccination are poverty and scarcity of human resources in those parts of the world who are most badly in need of these vaccines. Despite their proven immunogenicity hepatitis B vaccines are unable to induce an adequate immune response in 5-10% of healthy adults. The non-responsiveness of these subjects is a selective phenomenon and not the expression of a general immune deficiency. Studies that correlated the HLA haplotype of vaccine recipients with their anti-HBs response patterns has led to the identification of markers of good and non/poor response. Universal vaccination of neonates and children has elicited questions about the durability of antibody persistence and the need for booster doses later in life. The European Consensus Group on Hepatitis B Immunity has proposed a series of recommendations that are summarized in this review.

Lifelong protection against hepatitis B: the role of vaccine immunogenicity in immune memory

Long-term protection against hepatitis B (HB) disease is dependent on persistence of a strong immune memory. This paper presents and discusses new knowledge that allows a better understanding of the mechanisms of long-term protection following hepatitis B vaccination. Studies have revealed links between specific lymphoproliferation, the in vivo humoral response and immune memory. The strength of immune memory and of a subsequent secondary immune response can therefore be predicted by the antibody response following primary vaccination. Vaccine antigen dose and structure have been identified as important influences in the primary antibody response and development of immune memory. The data and considerations presented support the use of highly immunogenic HB vaccines in order to provide long-lasting protection against HB disease.

Are booster immunisations needed for lifelong hepatitis B immunity? European Consensus Group on Hepatitis B Immunity

Long-term protection against clinically significant breakthrough hepatitis B (HB) virus infection and chronic carriage depends on immunological memory, which allows a protective anamnestic antibody response to antigen challenge. Memory seems to last for at least 15 years in immunocompetent individuals. To date there are no data to support the need for booster doses of HB vaccine in immunocompetent individuals who have responded to a primary course. All adequately vaccinated individuals have shown evidence of immunity in the form of persisting anti-HBs and/or in vitro B-cell stimulation or an anamnestic response to a vaccine challenge. Nonetheless several countries and individuals currently have a policy of administering booster doses to certain risk groups. Boosters may be used to provide reassurance of protective immunity against benign breakthrough infection. For immunocompromised patients, regular testing for anti-HBs, and a booster injection when the titre falls below 10 mIU/mL, is advised. Long-term monitoring should continue, to confirm the absence of clinically significant breakthrough episodes of hepatitis B and to find out if a carrier state develops after 15 years. Also, non-responders to a primary course should continue to be studied.

Over a decade of experience with a yeast recombinant hepatitis B vaccine

Experience with the yeast recombinant hepatitis B vaccine Engerix-B now exceeds 10 years. We reviewed published studies on this vaccine. These show the vaccine to be safe, causing mostly only minor local symptoms and to be highly immunogenic both in monitored clinical trials and under field conditions. Engerix-B consistently elicits high geometric mean antibody titres and a high protective efficacy has been established in three groups at high-risk of hepatitis B infection, homosexual men, institutionalised mentally handicapped subjects and neonates of chronic carrier mothers. The profile of the recombinant hepatitis B vaccine in certain high-risk groups and immuno compromised people is discussed. Finally we present updated post marketing surveillance data based on 496 million distributed doses of vaccine.

Booster vaccination with recombinant hepatitis B vaccine four years after priming with one single dose

We here studied the antibody response to a booster dose four years after the administration of one single dose of recombinant HB vaccine. Before receiving the booster dose, levels of protective antibodies (anti-HBs) were generally low and 24/41 (59%) individuals lacked detectable antibodies (< 1 IU/L). Within 14 d of booster vaccination, 36/38 (95%) vaccinees showed levels of antibodies > 100 IU/L. Notably, these levels were at least as high as those of a reference group 12 months after initiation of vaccination according to the standard three-dose vaccination at intervals of 0, 1 and 6 months. In conclusion, one single dose of HB vaccine seemed to confer on young healthy individuals a well preserved B cell memory, disclosed as a rapid and strong antibody response to a second dose four years later.

A mathematical model predicting anti-hepatitis B virus surface antigen (HBs) decay after vaccination against hepatitis B

The determination of serum levels of antibodies against hepatitis B virus surface antigen (anti-HBs) after hepatitis B vaccination is currently the only simple test available to predict the decay of protection and to plan the administration of booster doses. A total of 3085 vaccine recipients of plasma-derived and recombinant vaccine have been followed for 10 years to determine the kinetics of anti-HBs production and to construct a mathematical model which could efficiently predict the anti-HBs level decline. The anti-HBs peak level was reached 68 days after the last dose of recombinant vaccine and 138 days after the last dose of plasma-derived vaccines. The age of vaccinees negatively influenced the anti-HBs levels and also the time necessary to reach the anti-HBs peak. A bilogarithmic mathematical model (log10 level, log10 time) of anti-HBs decay has been constructed on a sample of recombinant vaccine recipients and subsequently validated on different samples of recombinant or plasma-derived vaccine recipients. Age, gender, type of vaccine (recombinant or plasma-derived), number of vaccine doses (three or four) did not influence the mathematical model of antibody decay. The program can be downloaded at the site: http:@www2.stat.unibo.it/palareti/vaccine.htm . Introducing an anti-HBs determination obtained after the peak, the program calculates a prediction of individual anti-HBs decline and allows planning of an efficient booster policy.

Twelve-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine versus plasma-derived vaccine without booster doses in children

A total of 318 children were prospectively randomized in group 1 with two 5-microg doses of recombinant vaccine given at 0 and 1 month; in group 2 with three 5-microg doses of recombinant vaccine given at 0, 1, and 6 months; or in group 3 with three doses of plasma-derived vaccine given at 0, 1, and 6 months. Eleven subjects with a hepatitis B surface antigen antibody (anti-HBs) titer of less than 10 mIU/mL at 12 months were given an extra dose of vaccine and were excluded from analysis. No booster doses were given to any other subjects. All children were followed up yearly for the level of anti-HBs titers and for the detection of hepatitis B infection. At the 12th year of follow-up, there were significantly fewer subjects with anti-HBs of 10 mIU/mL or above in group 1 (60.4%) when compared with group 2 (81.4%; P =.0287) and group 3 (79.0%; P =. 0381). The geometric mean titers (GMTs) of subjects of group 1 were significantly lower than those of group 2 and group 3 throughout the 12 years of follow-up. A total of 65 subjects had one or more episodes of anamnestic response. No subject became positive for hepatitis B surface antigen (HBsAg); 2 became positive for hepatitis B core antigen antibody (anti-HBc). In conclusion, the long-term protective immunity was better with three doses of hepatitis B vaccine (either the recombinant or plasma-derived) than with two doses. However, protection from hepatitis B infection could be equally achieved by either two doses or three doses of the vaccine. Booster doses were not necessary, probably because of effective anamnestic response.

Hepatitis B vaccine: current issues

OBJECTIVE

To review two main issues concerning the hepatitis B vaccine: (1) the management of unresponsive subjects and (2) the need for routine booster doses.

DATA SOURCES

Pertinent literature identified via MEDLINE (1980-1996) search as well as references cited in published articles.

DATA SYNTHESIS

The optimal procedure for management of subjects unresponsive to hepatitis B vaccine has not been well established. Most unresponsive subjects are not absolute nonresponders, since most of them can develop protective concentrations of antibodies to hepatitis B surface antigen (anti-HBsAg) after hepatitis B revaccination, consisting of a fourth or a fifth dose or a new complete course of immunization. In subjects who do not respond to the hepatitis B vaccine after four or more injections, the benefits of the combination of cytokines (e.g., interferon-alfa, interleukin-2 [aldesleukin]) and vaccine have not been clearly shown. There are two main opinions regarding the need for routine booster doses. Experts from the US, claiming long-term protection from immunologic memory, suggest delaying booster doses for at least a decade after vaccination in subjects with normal immune status. Furthermore, postvaccination antibody testing should be restricted only to high-risk subjects. Once a vaccinated subject has responded satisfactorily, further antibody tests are unnecessary. Only hemodialysis patients should be tested annually for adequate antibody concentrations and the booster dose administered when concentrations decline to less than 10 IU/L. Experts from Europe suggest that vaccine-induced antibody responses should be assessed in all subjects and booster doses administered at intervals, with the theory being that protection correlates with the presence of antibody. However, indications about appropriate timing for booster doses and target titers of anti-HBsAg remain controversial.

CONCLUSIONS

It is possible to obtain seroconversion in nonresponders by using variations in vaccination strategies (i.e., > 3 doses, double amounts of HBsAg). Adjuvants such as interferon-alfa or aldesleukin are of limited use. The opinions of American experts regarding routine booster doses, as expressed by the statement of the Immunization Practices Advisory Committee, seem to be well defined and helpful to clinicians trying to resolve controversies for individual patients. The opinions of the European experts are not unanimous and are sometimes impractical. A consensus conference is needed.

Nonresponse to hepatitis B vaccines and the kinetics of anti-HBs production

No empirical data are available for the anti-HBs title required for protection against infection with the hepatitis B virus (HBV), but nonresponders to hepatitis B vaccines remain susceptible to infection. There may be an unexplained qualitative difference between hyporesponders and true nonresponders, but there is a clear association with HLA haplotypes. There is no evidence for silent infection with HBV in nonresponders.

Intradermal hepatitis B vaccination in a 300-bed primary care hospital: experience with a recombinant vaccine in a four-dose schedule

BACKGROUND

All hepatitis B vaccination programs, regardless of route, must address such factors as primary response rate, additional booster injections for primary nonresponders, antibody persistence, the need for and timing of additional booster injections for primary responders, overall costs, and medical efficacy. A voluntary intradermal hepatitis B vaccination program with postvaccination testing was implemented in a 300-bed primary care hospital with a recombinant vaccine packaged in a concentration of 20 micrograms/ml (Engerix B; SmithKline and French Laboratories, Philadelphia, Pa.).

METHODS

After informed consent was obtained, 460 employees were vaccinated intradermally over the deltoid muscle by a single employee health nurse at months 0 (initial), 1, 2, and 6, followed by testing for serologic response 1 to 2 months after the final dose.

RESULTS

Of 411 employees who completed the entire protocol, 90.5% had seroconversion, as determined by enzyme immunoassay. Twelve of 29 primary nonresponders (41%) had seroconversion after an additional (fifth) intradermal booster injection. Of the primary responders, 84.5% remained seropositive when tested 18 months after the initial vaccination injection. These results are comparable to those of intramuscular vaccination and to the original studies of intradermal vaccination with plasma-derived vaccines that had shown excellent immunogenicity.

CONCLUSIONS

Intradermal and intramuscular hepatitis B vaccination programs must be implemented in somewhat different ways, but both can provide excellent protection against hepatitis B viral infection. Even allowing for the additional expense of postvaccination testing and more frequent booster injections, intradermal vaccination greatly reduces the overall costs of hepatitis B vaccination and may therefore increase compliance in many different settings.

Five-year follow-up of a prospective randomized trial of hepatitis B recombinant DNA yeast vaccine vs. plasma-derived vaccine in children: immunogenicity and anamnestic responses

In a prospective randomized trial, 318 children aged between 3 mo and 11 yr who were negative for all hepatitis B markers were randomized to receive two 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0 and 1 mo (group 1), three 5-micrograms doses of hepatitis B recombinant DNA yeast vaccine at 0, 1 and 6 mo (group 2) or three 10-micrograms doses of plasma-derived hepatitis B vaccine (group 3). The HBs antibody response rate at 8 mo was between 93% and 99%; it was still 75% to 87% at 5 yr in all three groups. Geometric mean titers at 1 yr were 83, 1,085 and 858 mIU/ml in groups 1, 2 and 3, respectively. These values had decreased after 5 yr to 47, 131 and 250 mIU/ml. Subjects in group 1 showed a significantly less proportional drop in geometric mean titer at the fifth year than did subjects in group 2 (p = 0.05) or group 3 (p = 0.015). None of the children developed HBc antibody, even after 5 yr of follow-up. We noted 42 episodes of significantly increased HBs antibody titers, probably due to anamnestic response, even when the titers had dropped to low levels. The mean age at which anamnestic response occurred was 8.7 yr.(ABSTRACT TRUNCATED AT 250 WORDS)

A 7-year follow-up of newborns vaccinated against hepatitis B

Of 79 children born to asymptomatic HBsAg chronic carrier mothers and vaccinated at birth against hepatitis B, a total of 71, 66 and 56 could be serologically assessed after 1, 5 and 7 years, respectively. Anti-HBs titres (geometric means) of responders decreased from 2475 to 143 IU l-1 between 1 and 5 years of age and dropped to 82 IU l-1 by 7 years. At this time, a booster dose given to 34 children who showed anti-HBs titres lower or slightly higher than 100 IU l-1 significantly increased titres from 34 to 2985 IU l-1 (p < 0.001). Children whose titres following perinatal vaccination reached 100 to 1000 IU l-1 or above 1000 IU l-1 maintained protective levels (> 10 IU l-1) for 3 and 5 years, respectively. As in adults, anti-HBs titres recorded after the initial vaccination indicate the time at which infants should receive booster vaccination.

Management guidelines for health care workers exposed to blood and body fluids

The purpose of this article is to propose specific management guidelines for the immediate emergency department and subsequent occupational health treatment of health care workers (HCWs) following accidental exposures to blood or body fluids. These guidelines are based on a collective review of the literature and the recommendations of the Advisory Committee on Immunization Practices (ACIP) and authorities expert in this knowledge domain. Guidelines are needed to assure appropriate treatment and coordinated efforts by ED and occupational health providers. Although numerous infections can potentially be transmitted by exposure to blood and body fluids, these guidelines are intended only for evaluation and postexposure prophylaxis of hepatitis B, hepatitis C, and infection with HIV.

Four-year experience with a recombinant hepatitis B vaccine

Three hundred and forty-three healthy adults were vaccinated with five different lots of recombinant hepatitis B vaccine. Three hundred and forty (99.1%) individuals produced antibodies against hepatitis B surface antigen (anti-HBs). Peak anti-HBs concentrations were significantly higher in females and younger individuals. All anti-HBs positive individuals developed antibodies to the common determinant "a" of HBsAg. The vaccine was well tolerated, without severe side reactions. Persistence of anti-HBs was followed in 130 individuals for 3, and in 15 for 4 years after the first vaccination of these two groups. 21.7% and 32.3%, respectively, no longer had protective levels of anti-HBs after this time. The persistence of anti-HBs was dependent on peak anti-HBs levels, with consistent kinetics of anti-HBs decline. Revaccination of individuals whose specific antibody levels had fallen below 10 IU/l led to a prompt anti-HBs response. Comparison with individuals vaccinated with plasma-derived hepatitis B vaccine revealed no substantial differences between the two vaccines.