Simultaneous administration of diphtheria-tetanus-pertussis-polio and hepatitis B vaccines in a simplified immunization program: immune response to diphtheria toxoid, tetanus toxoid, pertussis, and hepatitis B surface antigen

Novel adjuvants in allergen-specific immunotherapy: where do we stand?

Type I hypersensitivity, or so-called type I allergy, is caused by Th2-mediated immune responses directed against otherwise harmless environmental antigens. Currently, allergen-specific immunotherapy (AIT) is the only disease-modifying treatment with the potential to re-establish clinical tolerance towards the corresponding allergen(s). However, conventional AIT has certain drawbacks, including long treatment durations, the risk of inducing allergic side effects, and the fact that allergens by themselves have a rather low immunogenicity. To improve AIT, adjuvants can be a powerful tool not only to increase the immunogenicity of co-applied allergens but also to induce the desired immune activation, such as promoting allergen-specific Th1- or regulatory responses. This review summarizes the knowledge on adjuvants currently approved for use in human AIT: aluminum hydroxide, calcium phosphate, microcrystalline tyrosine, and MPLA, as well as novel adjuvants that have been studied in recent years: oil-in-water emulsions, virus-like particles, viral components, carbohydrate-based adjuvants (QS-21, glucans, and mannan) and TLR-ligands (flagellin and CpG-ODN). The investigated adjuvants show distinct properties, such as prolonging allergen release at the injection site, inducing allergen-specific IgG production while also reducing IgE levels, as well as promoting differentiation and activation of different immune cells. In the future, better understanding of the immunological mechanisms underlying the effects of these adjuvants in clinical settings may help us to improve AIT.

Engineering Optimal Vaccination Strategies: Effects of Physical Properties of the Delivery System on Functions

With rapid developments in medical science and technology, vaccinations have become the key to solving public health problems. Various diseases can be prevented by vaccinations, which mimic a disease by...

Mannose-Functionalized Biodegradable Nanoparticles Efficiently Deliver DNA Vaccine and Promote Anti-tumor Immunity

Cancer vaccines have attracted increasing attention for their application in tumor immunotherapy. DNA vaccines are one of them that have been proven very promising with the advantages of safety, rapid design, and low cost. However, the low stability, ineffective cell internalization, and low immunostimulation hinder their wide application. Thus, developing targeted and safe systems to effectively deliver DNA vaccines becomes a vital step. In this study, we report the development of mannose- and bisphosphonate (BP)-modified calcium phosphate (CP) nanoparticles (NPs) as efficient vaccine delivery vehicles by targeting C-type lectin receptors (CLRs) on antigen-presenting cells (APCs). Using a model antigen ovalbumin (OVA)-encoded plasmid DNA (pOVA) as a model vaccine, we demonstrate that mannose-modified and BP-stabilized CP (MBCP) nanoparticles are mono-dispersed for enhanced uptake by APCs and subsequently induce OVA antigen presentation and immunostimulation. Mice immunized with MBCP-pOVA nanovaccines show a significantly stronger anti-OVA antibody response with a quicker IgG1 and IgG2a antibody production than unmodified NPs. Moreover, MBCP-pOVA immunization significantly inhibits the growth of OVA-expressing E.G7 tumor cells in C57BL/6J mice. Our data collectively suggest that the modifications to enhance the stability and targeting ability of MBCP NPs are essential for effective delivery of DNA vaccines and promote robust anti-tumor immunity.

Rod-Scale Design Strategies for Immune-Targeted Delivery System toward Cancer Immunotherapy

Strengthening the antitumor immune response to surpass the activation energy barrier associated with the immunosuppressive tumor microenvironment is an active area of cancer immunotherapy. Emerging evidence suggests that delivery of immunostimulatory molecules with the aid of a carrier system is essential for cancer immunotherapy. However, the size-dependent effect of the delivery system on immune-targeted sites and anticancer immune responses is yet to be comprehensively understood. Herein, to clarify the size-dependent effect of the delivery system on the underlying anticancer immune mechanism, rod-shaped hydroxyapatite (HA) particles with lengths from 100 nm to 10 μm are designed. HA rods stimulate anticancer immunity in a size-dependent manner. Shorter HA rods with lengths ranging from 100 to 500 nm promote antigen cellular uptake, dendritic cell (DC) maturation, and lymph node targeting antigen. In contrast, longer HA rods with lengths ranging from 500 nm to 10 μm prolong antigen retention and increase DC accumulation. Medium-sized HA rods with a length of 500 nm, taking advantage of both short and long rods, show optimized antigen release and uptake, increased DCs accumulation and maturation, highest CD4⁺ and CD8⁺ T cell population, and the best anticancer immunity in vivo. The present study provides a rod-scale design strategy for an immune-targeted delivery system toward cancer immunotherapy in the future.

Tailoring inorganic nanoadjuvants towards next-generation vaccines

Vaccines, one of the most effective and powerful public health measures, have saved countless lives over the past century and still have a tremendous global impact. As an indispensable component of modern vaccines, adjuvants play a critical role in strengthening and/or shaping a specific immune response against infectious diseases as well as malignancies. The application of nanotechnology provides the possibility of precisely tailoring the building blocks of nanoadjuvants towards modern vaccines with the desired immune response. The last decade has witnessed great academic progress in inorganic nanomaterials for vaccine adjuvants in terms of nanometer-scale synthesis, structure control, and functionalization design. Inorganic adjuvants generally facilitate the delivery of antigens, allowing them to be released in a sustained manner, enhance immunogenicity, deliver antigens efficiently to specific targets, and induce a specific immune response. In particular, the recent discovery of the intrinsic immunomodulatory function of inorganic nanomaterials further allows us to shape the immune response towards the desired type and increase the efficacy of vaccines. In this article, we comprehensively review state-of-the-art research on the use of inorganic nanomaterials as vaccine adjuvants. Attention is focused on the physicochemical properties of versatile inorganic nanoadjuvants, such as composition, size, morphology, shape, hydrophobicity, and surface charge, to effectively stimulate cellular immunity, considering that the clinically used alum adjuvants can only induce strong humoral immunity. In addition, the efforts made to date to expand the application of inorganic nanoadjuvants in cancer vaccines are summarized. Finally, we discuss the future prospects and our outlook on tailoring inorganic nanoadjuvants towards next-generation vaccines.

Adjuvants for Clostridium tetani and Clostridium diphtheriae vaccines updating

It's known that diphtheria and tetanus are a contagious lethal diseases over the years, they caused by pathogenic microbes corynebacterium diphtheria and Clostridium tetani, respectively. The diseases result from the production of bacterial toxin. Vaccination with bacterial toxoid vaccines adsorbed on particulates adjuvants still are the best way to prevent this epidemic diseases from spread. The particulate vaccines have been shown to be more efficient than soluble one for the induction of the immune responses. Nanoparticles can be engineered to enhance the immune responses. As well known the immune response to inactivate killed and subunit vaccine enhances by alum adjuvants. The adjuvants examined and tested after reducing its size to particle size, thus mimic size of viruses which is considered smallest units can derive the immune system. The major issue is minimizing the adjuvant particles, to gain insight of resulting immunity types and impact on immune response. The adjuvant effect of micro/nanoparticles appears to largely be a consequence of their uptake into antigen presenting cells.

Mineral Adjuvants∗∗The present chapter is an updated version of the chapter “Mineral Adjuvants,” published in Immunopotentiators in Modern Vaccines, p. 217–233. Ed. Virgil Schijns & Derek O'Hagan, Elsevier Science Publishers (2005)

Mineral adjuvants comprise aluminum hydroxide and phosphate adjuvants as well as calcium phosphate adjuvants. In particular, the aluminum salts have achieved an undisputed status as the most commonly used adjuvants in human and veterinary vaccines. Calcium phosphate adjuvant, later discovered by Edgar Relyveld, constitutes a very interesting alternative and has also been applied both in human and veterinary vaccines. New analytical tools applied in adjuvant research are about to take us to the next level of understanding mineral adjuvants. These tools have been used to characterize mineral adjuvants, but so far, in particular, aluminum-based adjuvants in terms of surface marker expression profiles, isotypic profiles, and cytokine profiles. In the past 10 years, the discovery of adjuvant-mediated induction of the NALP3 inflammasome and its impact on the secretion of interleukin (IL)-1β and IL-18 as proinflammatory mediators in the early phases of immune response has been described as an important mechanism for the function of these adjuvants.

Hepatitis B vaccination status and needlestick injuries among healthcare workers in syria

Background:

Although a majority of countries in the Middle East show intermediate or high endemicity of hepatitis B virus (HBV) infection, which clearly poses a serious public health problem in the region, the situation in the Republic of Syria remains unclear. The aim of this study is to determine the hepatitis B vaccination status, to assess the number of vaccinations administered, and to estimate the annual incidence of needlestick injuries (NSIs) among healthcare workers (HCWs) in Aleppo University hospitals.

Materials and Methods:

A cross-sectional design with a survey questionnaire was used for exploring details of NSIs during 2008, hepatitis B vaccination status, and HBV infection among a random stratified sample of HCWs in three tertiary hospitals in Aleppo (n = 321).

Results:

Two hundred and forty-six (76.6%) HCWs had sustained at least one NSI during 2008. Nine (2.8%) had HBV chronic infection and 75 HCWs (23.4%) were never vaccinated. Anesthesiology technicians had the greatest exposure risk when compared to office workers [OR = 16,95% CI (2.55-100), P < 0.01], doctors [OR = 10,95% CI (2.1 47.57), P < 0.01], and nurses [OR = 6.75,95% CI (1.56-29.03), P = 0.01]. HCWs under 25 and between the age of 25 and 35 years were at increased risk for NSI when compared to HCWs older than 45 years [OR = 3.12,95% CI (1.19-8.19), P = 0.02] and [OR = 3.05,95% CI (1.42-6.57), P < 0.01], respectively.

Conclusion:

HCWs at Aleppo University hospitals are frequently exposed to blood-borne infections. Precautions and protection from NSIs are important in preventing infection of HCWs. Education about the transmission of blood-borne infections, vaccination, and post-exposure prophylaxis must be implemented and strictly monitored.

Protective efficacy of a recombinant plague vaccine when co-administered with another sub-unit or live attenuated vaccine

Vaccines against bioterrorism agents offer the prospect of providing high levels of protection against airborne pathogens. However, the diversity of the bioterrorism threat means that it may be necessary to use several vaccines simultaneously. In this study we have investigated whether there are changes to the protective immune response to a recombinant sub-unit plague vaccine when it is co-administered with other sub-unit or live attenuated vaccines. Our results indicate that the co-administration of these vaccines did not influence the protection afforded by the plague vaccine. However, the co-administration of the plague sub-unit vaccine with a live vaccine resulted in markedly increased levels of IgG2a subclass antibodies, and markedly reduced levels of IgG1 subclass antibodies, to the plague sub-unit vaccine. This finding might have implications when considering the co-administration of other vaccine combinations.

Undervaccination with hepatitis B vaccine: missed opportunities or choice?

BACKGROUND

An estimated 1 million to 1.25 million people in the United States are chronically infected with hepatitis B virus (HBV) and are at substantially increased risk of developing chronic liver disease, including cirrhosis and primary hepatocellular carcinoma. Immunization with hepatitis B vaccine (HepB) is the most effective means of preventing HBV infection and its consequences.

METHODS

To identify and describe children who had not completed the three-dose HepB series, we analyzed data from the 1999 National Immunization Survey (NIS). Among the 2648 children aged 19 to 35 months who did not complete the HepB series, we examined the relationship between the number of doses of HepB received and the number of vaccination visits made, receipt of the birth dose of HepB, age at the time of first vaccination visit (excluding that for the birth dose of HepB), and completion of the 4:3:1:3 series (four doses of diphtheria and tetanus toxoids and pertussis vaccine, three doses of poliovirus vaccine, one dose of measles-containing vaccine, and three doses of Haemophilus influenzae type b vaccine [Hib]).

RESULTS

Overall, 11.8% of the children who were included in the 1999 NIS did not complete the HepB series. Among these series-incomplete children, most (79.8%; 95% CI, 77.4%-82.2%) did not receive the birth dose of HepB, and most (80.2%; 95% CI, 77.6%-82.8%) had three or more vaccination visits. Most of the series-incomplete children (87.3%; 95% CI, 85.1%-89.5%) who had three or more vaccination visits received one or two doses of HepB. Among series-incomplete children with at least three vaccination visits, those who did not receive any HepB were more likely to have completed the 4:3:1:3 series (67.1%; 95% CI, 58.8%-75.4%) than those who received at least one dose of HepB (52.7%; 95% CI, 49.0%-56.4%).

CONCLUSIONS

Children who did not complete the HepB series fell into three distinct groups: children who made at least three vaccination visits but did not begin the HepB series (n=326); children who made three or more vaccination visits and received one or two doses of HepB (n=1835); and children who made fewer than three vaccination visits (n=487). Different intervention strategies are needed to have an impact on each of these groups, including understanding why parents and providers may not be receptive to HepB, decreasing missed opportunities to administer HepB, and implementing tracking systems such as registries to identify and contact children who are due or overdue for vaccinations.

Development and clinical application of new polyvalent combined paediatric vaccines

The availability of combined vaccines containing protective antigens against the majority of (ideally all) diseases for which universal immunization is recommended in infancy would simplify the implementation, increase the acceptance, reduce the global cost of immunization programmes and improve disease control, while offering the possibility of disease elimination or even pathogen eradication. The desirability of combined vaccines is further enhanced, and made more urgent, because of the increasing number of diseases that can be prevented by vaccination. The complicated logistics of administering different vaccines that each require several inoculations is a significant barrier to successful immunization of a population. Furthermore, interest in immunization is continuously gaining momentum since it is now generally recognised that vaccines are among the safest and most cost-effective medical interventions for infectious diseases that continue, in spite of the widespread use of efficacious antimicrobial drugs, to be an important cause of morbidity and mortality. This burden is likely to increase due to the development of antimicrobial resistance. Basic research on new vaccines or improvement of existing ones such as the use of new technologies may be carried out in academic or other non-industrial laboratories but development work, including the necessary extensive clinical testing, that lead to products that can be approved for routine use is usually co-ordinated and financed by commercial companies. The decision to develop any particular combined vaccine will therefore be influenced not only by its medical desirability and technical feasibility but also the potential financial returns that the required investments in time and resources may bring to the company. All major vaccine manufacturers are currently working, either alone or through strategic alliances, towards developing more polyvalent vaccines by adding antigens such as inactivated polio virus, conjugated Haemophilus influenzae type b polysaccharide and hepatitis B surface antigen to the diphtheria-tetanus-pertussis vaccine either in its 'classical' (whole-cell) or more purified (acellular) formulations. Experience is showing that the development of combined vaccines involves much more than the simple mixing of existing antigens. Possible incompatibilities or mutual interferences between the antigens themselves, or between excipients, preservatives, adjuvants, residual contaminants, stabilisers and suspending fluids make it mandatory that each formulation be thoroughly tested for quality, stability, efficacy and safety. Furthermore the ability to produce and control it consistently must be established before it can be licensed for commercial use. The progress being made in this field is reviewed.

Long-term antibody persistence after booster vaccination with combined tetravalent diphtheria tetanus, whole-cell Bordetella pertussis and hepatitis B vaccine in healthy infants

Combining HB vaccine with routine paediatric vaccines has been recognized as the best means of universal vaccination against hepatitis B. Our objective was to evaluate the long-term antibody persistence of such a combined vaccine in an area of high hepatitis B endemicity. We have shown that a DTPw-HB vaccine was safe and immunogenic when given as a booster dose at 18 months of age. One month after the booster dose of DTPw-HB vaccine, at least 97.8% of subjects had seroprotective anti-HBsAg levels, and 1 year later at least 93.9% of these subjects remained seroprotected against HBsAg. Immune responses to the DTPw components were similar or greater than those of the commercial DTPw vaccine given to the control group. This DTPw-HB vaccine, which showed good long-term anti-HBsAg antibody persistence, could advantageously replace separate DTPw and HB vaccines in areas of high hepatitis B endemicity in terms of clinical, economic and strategic benefits.

Safety and immunogenicity of a recombinant hepatitis B vaccine administered to infants at 2, 4 and 6 months of age. The Kaiser-UCLA Vaccine Study Group

A recombinant hepatitis B vaccine was administered to over 5000 infants in a prospective, randomized and blinded study. Infants were given either recombinant hepatitis B vaccine (Engerix-B, SmithKline Beecham Pharmaceuticals, 10 micrograms dose-1) or a Haemophilus influenzae type b (Hib) conjugate vaccine at 2, 4 and 6 months of age simultaneously with diphtheria-tetanus-pertussis and oral polio vaccines. Adverse reactions were ascertained by parental reports and interviews, and review of medical records. Blood specimens collected from 269 infants given hepatitis B vaccine were assayed for antibody to hepatitis B surface antigen (anti-HBs) by enzyme immunoassay. Infants given hepatitis B vaccine experienced low rates of adverse reactions that were similar or lower than the rates in infants given Hib conjugate vaccine. The geometric mean anti-HBs concentrations were 9.6 mIU ml-1 after one dose, 333 mIU ml-1 after two doses and 1812 mIU ml-1 after three doses (99% had levels > or = 10 mIU ml-1). Antibody responses to diphtheria and tetanus toxoids were unaffected by simultaneous administration of hepatitis B or Hib conjugate vaccine. Engerix-B vaccine was safe and immunogenic when given with other routine childhood immunizations at 2, 4 and 6 months of age, and should provide long-term protection against hepatitis B virus infection.

Tetanus immunization and its association to hepatitis B vaccination in patients with chronic renal failure

A defect in the immune response of patients with chronic renal failure leads to low response rates and insufficient antibody concentrations following a number of highly recommended vaccinations. This has been shown before for immunization against hepatitis B and influenza. Few data are available concerning the efficacy of vaccination with tetanus toxoid in these patients. In a prospective, controlled study we vaccinated seronegative patients with chronic renal failure not on dialysis, patients on chronic intermittent hemodialysis, and patients after kidney transplantation with tetanus toxoid. The results were compared with those of a control group consisting of 13 age-matched patients with mild essential hypertension and normal kidney function. Only 11 of 20 (55%) patients in the chronic renal failure group and 16 of 23 (69%) in the dialysis group had a protective antibody response after triple vaccination. In contrast, all the patients in the control group and six of seven transplant patients seroconverted. The response to tetanus toxoid was highly associated with the response to a previously administered vaccination against hepatitis B. Responders to this vaccination also had a better response rate to tetanus toxoid. The antibody concentrations after vaccination were lower in all patient groups compared with the controls; the lowest titers were found in the transplant patients. Therefore, renal patients will need revaccination much earlier, and tetanus toxoid antibody levels should be checked if a patient is injured and potentially requires vaccination.

Simultaneous injection of plasma-derived or recombinant hepatitis B vaccines with yellow fever and killed polio vaccines

Previous studies have shown an absence of interaction between hepatitis B (HB) vaccine and other vaccines used in EPI programmes except for an apparent decrease of yellow fever antibody levels when hepatitis B and yellow fever vaccines are given simultaneously. We have therefore reinvestigated the interaction of these two vaccines and assessed the absence of interaction between inactivated polio vaccine and recombinant or plasma-derived HB vaccine. The immune responses to polio vaccine injected simultaneously with plasma-derived or recombinant HB vaccine were observed to be equivalent and similar to those observed in the literature. In this randomized study, the immune responses to yellow fever injected simultaneously with plasma-derived or recombinant HB vaccine were comparable to those observed after separate administration of each vaccine. Moreover, no increase in adverse reactions was noted.

Adjuvant properties of aluminum and calcium compounds

It is likely that aluminum compounds will continue to be used with human vaccines for many years as a result of their excellent track record of safety and adjuvanticity with a variety of antigens. For infections that can be prevented by induction of serum antibodies, aluminum adjuvants formulated under optimal conditions are the adjuvants of choice. It is important to select carefully the type of aluminum adjuvant and optimize the conditions of adsorption for every antigen since the degree of adsorption of antigens onto aluminum adjuvants markedly affects immunogenicity. The mechanism of adjuvanticity of aluminum compounds includes formation of a depot at the site of injection from which antigen is released slowly; stimulation of immune-competent cells of the body through activation of complement, induction of eosinophilia, and activation of macrophages; and efficient uptake of aluminum-adsorbed antigen particles by antigen-presenting cells because of their particulate nature and optimal size (< 10 microns). Limitations of aluminum adjuvants include local reactions, production of IgE antibodies, ineffectiveness for some antigens, and inability to elicit cell-mediated immune responses especially cytotoxic T-cell responses. Calcium phosphate, which has adjuvant properties similar to aluminum adjuvants, has the potential advantages of being a natural component of the body and of not increasing IgE production. There is a need for alternative adjuvants, particularly for diseases in which cell-mediated immune responses are important for prevention or cure.

A framework for the evaluation of vaccines for use in the expanded programme on immunization

Since 1974, the Expanded Programme on Immunization (EPI) has provided technical support for the immunization of the world's children and women of childbearing age. Today, the vast majority of vaccines administered to these groups are delivered through the immunization programmes that have been established in developing countries. As these national programmes share many characteristics, the global use of a new or improved vaccine could be largely dependent on its compatibility with the priorities, existing antigens and vaccine delivery system of this network. Consequently, a framework has been developed for the systematic evaluation of candidate vaccines for use in EPI.

Simultaneous administration of hepatitis B vaccine with other E.P.I. vaccines

Development of recombinant DNA vaccine against hepatitis B grown on cultured yeast cell has made it possible to mount a world-wide effort to control and eradicate Hepatitis B infection. However, the currently recommended schedules (0, 1 & 2 months, and 0-1 and 6 months) do not coincide with the scheduled visits for other E.P.I. vaccines, and necessitate additional visits for Hepatitis B vaccination. This study was therefore carried out to find out if adequate seroconversion occurs to Hepatitis B vaccine when given with other EPI vaccines or not? Thirty nine infants born to Australia antigen positive mothers from among 850 screened pregnant mothers were recruited to receive Hepatitis B vaccine (Engerix B-10 micro gram each) at 0, 6 and 14 wks (group A) or at 0, 1 and 2 months (group B). Thirty-one infants were recruited in group A and 8 in group B. The cord blood was collected and the first dose of vaccine was given within 48 hours of birth. Simultaneous B.C.G. was given at the left deltoid. Other E.P.I. vaccines were given qt 6, 10 and 14 wks in group A and at 2, 3 and 4 months in group B. Repeat blood samples were collected prior to giving each dose of Hepatitis B vaccine, and 4 weeks after the last dose. All blood samples were assayed for HBsAg and HBsAb at the National Institute Of Communicable Diseases, utilizing standard ELISA kits. The seroconversion rates following one, two and three doses of Hepatitis B vaccine were 3.33%, 55.5%, 96.15% and 0%, 62.5% and 100% in group A and B respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Humoral response in rabbits immunized with calcium phosphate adjuvanted HIV-1 gp160 antigen

Rabbits were immunized with either calcium phosphate adjuvanted purified HIV-1 gp160 or a fluid preparation. Circulating antibodies were detected by ELISA, RIPA and Western Blot tests. Sera of rabbits immunized with the adjuvanted preparation contained high levels of anti-gp160 antibodies, as well as antibodies recognizing p55, p25 and p18. On the contrary, rabbits immunized with the fluid preparation contained only anti-p18 antibodies. Neutralizing antibodies were also detected. It is concluded that the calcium phosphate adjuvant could be used for preparation of candidate anti-HIV vaccines, since it permits one to induce high levels of circulating antibodies, in the absence of untoward reactions as observed when aluminium adjuvants or water in oil emulsions are used.

Preventing neonatal hepatitis B infection during the perinatal period

In the United States, hepatitis B virus (HBV) infection is a growing problem with serious long-term consequences. Because previous vaccination programs have been ineffective in lowering the incidence of HBV, the U.S. Centers for Disease Control now recommend a comprehensive plan to reduce transmission of the virus. This article explores the epidemiology of HBV infection, the use of hepatitis B immune globulin and hepatitis B vaccines, and current recommendations for eliminating transmission of HBV during the perinatal period.

Adjuvants--a balance between toxicity and adjuvanticity

Adjuvants have been used to augment the immune response in experimental immunology as well as in practical vaccination for more than 60 years. The chemical nature of adjuvants, their mode of action and the profile of their side effects are highly variable. Some of the side effects can be ascribed to an unintentional stimulation of different mechanisms of the immune system whereas others may reflect general adverse pharmacological reactions. The most common adjuvants for human use today are still aluminium hydroxide, aluminium phosphate and calcium phosphate although oil emulsions, products from bacteria and their synthetic derivatives as well as liposomes have also been tested or used in humans. In recent years monophosphoryl lipid A, ISCOMs with Quil-A and Syntex adjuvant formulation (SAF) containing the threonyl derivative of muramyl dipeptide have been under consideration for use as adjuvants in humans. At present the choice of adjuvants for human vaccination reflects a compromise between a requirement for adjuvanticity and an acceptable low level of side effects.

Immune response to simultaneous administration of a recombinant DNA hepatitis B vaccine and multiple compulsory vaccines in infancy

The reactogenicity and immunogenicity of simultaneous administration of recombinant DNA hepatitis B vaccine with diphtheria and tetanus toxoids (DT) and oral poliovirus vaccine (OPV) in 111 infants were compared with those of DT and OPV alone in a control group of 21 infants. All subjects received three doses of the vaccine according to one of three different schedules of vaccination. Reactions following simultaneous administration of vaccines were all but absent, with mild pain reported for four out of 111 subjects, compared with one of 21 in the control group. Seroconversion rates of 98-100% and high anti-HBs geometric mean titres (GMTs) were observed in all study groups after three doses of hepatitis B vaccine. Significantly higher anti-HBs were seen in Group III, where six months is allowed between the second and the third hepatitis B vaccine doses, compared with Group I and II, where only 1-2 months separate the second and third doses. A fourth dose of vaccine was needed in both these groups to obtain anti-HBs levels as high as seen in Group III after three vaccine doses at 3, 4 and 10 months of age. The immune response to DT and OPV was similar in the study groups and the control group. It is concluded that a course of 10 micrograms doses of recombinant hepatitis B vaccine given simultaneously with DT and OPV elicits a strong anti-HBs response and does not interfere with the immune response to the other antigens.

Integration of hepatitis B vaccination into rural African primary health care programmes

OBJECTIVE

To determine the efficacy of hepatitis B vaccine when added to the routine expanded programme on immunisation under field conditions in rural Africa.

DESIGN

Infants were immunised according to two schedules--an early schedule at birth, 3 months, and 6 months and a later schedule to correspond with routine vaccination in the expanded programme on immunisation at 3 months, 4 1/2 months, and 6 months.

SETTING

Venda, northern Transvaal, South Africa, a self governing region of 7460 square kilometers varying from rural villages to small towns.

SUBJECTS

The 1989 birth cohort of Venda.

MAIN OUTCOME MEASURES

Coverage for hepatitis B vaccine at first, second, and third doses; serological assessment of vaccine efficacy by prevalence of antibodies to hepatitis B surface antigen in infants who had completed the three dose course of immunisation; antibodies to hepatitis B core antigen to determine if natural infection occurred.

RESULTS

Vaccine coverage for hepatitis B dropped sharply from 99% to 53% to 39% for the first, second, and third dose respectively. In contrast, vaccine coverage was maintained at 97-99% for the three doses of poliomyelitis vaccine. Serological evaluation of vaccine efficacy showed that only 3.5% of recipients of all three doses failed to develop antibodies to hepatitis B surface antigen. Only 6.6% of vaccine recipients were vaccinated according to either the early or later schedules whereas 93.4% received their doses of vaccine at intervals beyond the limits of either of the planned schedules. There was, however, no significant difference in seroconversion to the surface antigen between the "unscheduled" or scheduled groups of those who were vaccinated according to the early or late schedules. The pattern of prevalence of antibodies to hepatitis B core antigen, which showed a sharp fall in children aged over 7 months, suggested that the antibodies were acquired passively rather than by active infection.

CONCLUSIONS

Supplementation of the present expanded programme on immunisation with hepatitis B vaccine in rural Africa is fraught with difficulties. However, the vaccine was effective within a fairly wide spacing of dosage. Adding hepatitis B vaccine to diphtheria, tetanus, and pertussis as a tetravalent vaccine is proposed as a means of effectively integrating it into the expanded programme on immunisation in Third World settings.

WHO strategy for the global elimination of new cases of hepatitis B

Hepatitis B infection and its sequelae remain major public health problems internationally despite the existence of sensitive tests to screen blood and blood products for hepatitis B surface antigen (HBsAg) and immunogenic vaccines. Since the human hepatitis B virus has no known animal reservoir, a systematic vaccination programme against hepatitis B, including vaccination of all newborns and young children within the framework of the WHO Expanded Programme on Immunization, as well as protection of high-risk individuals, together with the testing of all blood and blood products for HBsAg, could eliminate hepatitis B virus infection and its sequelae. However, for the successful realization of this programme, many important and difficult problems need to be solved, especially those related to vaccination strategy, determination of the duration of immunity, investigation of the mechanisms of perinatal and horizontal virus transmission, and improvement of the immunogenicity of hepatitis B vaccine. The problem of the hepatitis B carrier is also paramount as the eradication of hepatitis B can be achieved only after the 300 million carriers of the disease in the world today are either cured or dead.

Simultaneous administration of hepatitis B and yellow fever vaccines

In most developing countries, hepatitis B prevention is carried out early in life. In these countries, mobile immunization teams have a limited number of sessions to devote to each rural community; simultaneous administration of multiple antigens is thus normal practice. We compared the immune responses of Senegalese children to the separate or simultaneous injections of yellow fever and hepatitis B vaccines. Injections were given at the time of booster injection for hepatitis B vaccine. Yellow fever antibodies were detected in similar proportions in infants immunized with either yellow fever vaccine alone or yellow fever and hepatitis B vaccines simultaneously. However, a lower proportion of high yellow fever antibody levels were observed when the two vaccines were injected simultaneously. No reduction in the anamnestic response of antibodies against the surface antigen of hepatitis B virus (anti-HBs) was observed when yellow fever vaccine was injected at the same time as the booster dose of hepatitis B vaccine. Since no untoward reactions were noted, it is concluded that hepatitis B and yellow fever vaccines can be administered at the same time.