Development and clinical testing of multivalent vaccines based on a diphtheria-tetanus-acellular pertussis vaccine: difficulties encountered and lessons learned

Thermostability of a trivalent, capsomere-based vaccine for human papillomavirus infection

Currently licensed vaccines require a cold-chain to maintain efficacy. This cold-chain requirement reduces the availability of vaccines in resource-poor areas of the world. Commercially available human papillomavirus (HPV) vaccines protect against the most common HPV types related to cervical cancer; however, their impact is limited in many regions due to cold-chain requirements. The goal of this study was to test the thermostability of an adjuvanted, trivalent HPV L1 capsomere-based vaccine (containing HPV types 16, 18, and 31) that was formulated by using lyophilization to embed the antigens within a solid, glassy matrix. Thermal stabilities were determined by storing the vaccine formulations for 3 months at 50 °C, followed by immunization of BALB/c mice and measurement of antibody responses. Antibody responses to capsomere vaccines formulated with alum were unchanged after storage for 3 months at 50 °C. Neutralizing responses to these vaccines were unchanged by high-temperature storage, and were equivalent to those generated after administration of the commercially available liquid HPV vaccine Gardasil®9.

Identity, Structure and Compositional Analysis of Aluminum Phosphate Adsorbed Pediatric Quadrivalent and Pentavalent Vaccines

Purpose

The goal of this study is to set an empirical baseline to map the structure-function relation of the antigens from the commercialized vaccine products.

Methods

To study the structural changes of protein antigens after adsorption several analytical tools including DLS, FTIR, Fluorescence, LD, and SEM have been used.

Results

All antigens have shown wide range of hydrodynamic diameter from 7 nm to 182 nm. Upon adjuvantation, the size distribution has become narrow, ranging from 10 to 12 μm, and has been driven by the derived diameter of aluminum phosphate (AlPO₄) adjuvant. Further to examine size and morphology of adsorbed antigens, SEM has been used. The SEM results have demonstrated that the AlPO₄ adjuvant suspension and adsorbed proteins consist of submicron particles that form a continuous porous surface. Diphtheria Toxoid (DT), Tetanus Toxoid (TT), and chemically-modified Filamentous Haemagglutinin (FHA) have shown surface adsorption to AlPO_4. Secondary structure alpha-helix and beta-sheet content of DT and TT has increased after adsorption to AlPO₄ adjuvant as shown by FTIR, whereas no significant changes were noted for other protein antigens. The results from Intrinsic Fluorescence have shown a structural rearrangement in DT and TT, consistent with the FTIR results. Multivalent vaccine product identity has been determined by FTIR as unique fingerprint spectrum.

Conclusion

The globular proteins such as DT and TT have shown changes in secondary structure upon adsorption to AlPO₄, whereas fibrillar protein FHA has not been affected by adsorption. FTIR can be used as a lean technique to confirm product identity at different manufacturing sites.

Trends in Canadian infant pertussis hospitalizations in the pre- and post-acellular vaccine era, 1981-2016

OBJECTIVE

The acellular pertussis vaccine was introduced into the routine childhood immunization schedule across Canada in 1997-98 and adolescent booster doses were added between 1999 and 2005. We sought to assess the impact of these changes on infant pertussis hospitalizations and admissions to intensive care units (ICU) in Canada.

METHODS

Hospitalizations with a primary diagnosis of pertussis were extracted from the Canadian Discharge Abstract Database (DAD) for cases with hospital discharge dates between 1981 and 2016 using relevant ICD-9 and ICD-10 codes. Only cases with age less than one year at time of admission were included. Disease severity was assessed by admission to ICU. Cases were categorized into two periods: pre-program implementation period (1981-1995) and the post-program implementation period (2006-2016). Incidence rates, risk ratios, and rate differences were calculated for each period and comparisons for the two periods were done using chi-squared and t-tests. Quasi Poisson analysis was used to investigate trends.

RESULTS

When comparing the pre- and post-implementation periods, the average annual hospitalization rates for infants less than 1 year declined from 165.1 (95% CI 161.3, 168.9) to 33.6 (95% CI 31.6, 35.6) pertussis-related admissions per 100,000 population, with a corresponding reduction in the risk ratio of 4.9 (95% CI 4.6, 5.2). The risk of admission into an ICU was 1.58 times higher in the pre- versus post-implementation period while the highest reduction in average annual hospitalizations was 263.3 admissions per 100,000 population in infants 2 months of age. In the post-implementation period, infants less than 1 month of age had the highest average annual hospitalization rate at 126.6 (95% CI 113.1, 140.1) hospitalizations per 100,000 infants.

CONCLUSION

Infant pertussis hospitalizations have reduced greatly over time. Infants under 2 months of age remain the most at-risk age group for hospitalization and admission to ICU.

Preliminary study on the immunogenicity of a newly developed GCC Tdap vaccine and its protection efficacy against Bordetella pertussis in a murine intranasal challenge model

Purpose

Active reduced dose tetanus-diphtheria-acellular pertussis (Tdap) vaccination for adolescents and adults is necessary because waning immunity after primary diphtheria-tetanus-pertussis vaccination is related to the recent emergence of pertussis. This study was conducted to compare the immunogenicity and protection efficacy against Bordetella pertussis between a new GCC Tdap vaccine and a commercially available Tdap vaccine in a murine model.

Materials and Methods

BALB/c mice were immunized with two doses of diphtheria-tetanus-acellular pertussis (DTaP) vaccine for priming and a subsequent Tdap booster vaccination. According to the type of booster vaccine, mice were divided into four groups: commercially available Tdap vaccine in group 1 and GCC Tdap vaccines of different combinations of pertussis antigens in groups 2 to 4. Humoral and cell-mediated immune responses and protection efficacy using a murine intranasal challenge model after booster vaccination were compared among the four groups.

Results

Every group showed significant increases in antibody titers against pertussis antigens such as pertussis toxin, filamentous hemagglutinin, and pertactin after booster vaccination. Spleen cells showed both Th1 and Th2 cell-mediated immune responses stimulated by pertussis antigens in all groups without any significant difference. In the intranasal B. pertussis infection model, bacteria were eradicated in all groups five days after challenge infection.

Conclusion

This preliminary study did not show significantly different immunogenicity or protection efficacy of the new GCC Tdap vaccines compared to the commercially available Tdap vaccine, although a more extensive study is necessary to assess the differing efficacies of the new GCC Tdap vaccines.

Implementing new health interventions in developing countries: why do we lose a decade or more?

BACKGROUND

It is unclear how long it takes for health interventions to transition from research and development (R&D) to being used against diseases prevalent in resource-poor countries. We undertook an analysis of the time required to begin implementation of four vaccines and three malaria interventions. We evaluated five milestones for each intervention, and assessed if the milestones were associated with beginning implementation.

METHODS

The authors screened World Health Organization (WHO) databases to determine the number of years between first regulatory approval of interventions, and countries beginning implementation. Descriptive analyses of temporal patterns and statistical analyses using logistic regression and Cox proportional hazard models were used to evaluate associations between five milestones and the beginning of implementation for each intervention. The milestones were: (A) presence of a coordinating group focused on the intervention; (B) availability of an intervention tailored to developing country health systems; (C) international financing commitment, and; (D) initial and (E) comprehensive WHO recommendations. Countries were categorized by World Bank income criteria.

RESULTS

Five years after regulatory approval, no low-income countries (LICs) had begun implementing any of the vaccines, increasing to an average of only 4% of LICs after 10 years. Each malaria intervention was used by an average of 7% of LICs after five years and 37% after 10 years. Four of the interventions had similar implementation rates to hepatitis B vaccine (HepB), while one was slower and one was faster than HepB. A financing commitment and initial WHO recommendation appeared to be temporally associated with the beginning of implementation. The initial recommendation from WHO was the only milestone associated in all statistical analyses with countries beginning implementation (relative rate = 1.97, P < 0.001).

CONCLUSIONS

Although possible that four milestones were not associated with countries beginning implementation, we propose an alternative interpretation; that the milestones were not realized early enough in each intervention's development to shorten the time to beginning implementation. We discuss a framework built upon existing literature for consideration during the development of future interventions. Identifying critical milestones and their timing relative to R&D, promises to help new interventions realize their intended public health impact more rapidly.

Challenge with a hepatitis B vaccine in two cohorts of 4-7-year-old children primed with hexavalent vaccines: an open-label, randomised trial in Italy

BACKGROUND AND AIMS

The anamnestic response to a challenge dose of vaccine can assess immune memory and protection against hepatitis B infection. This study investigated responses to a challenge dose of monovalent hepatitis B vaccine in children immunised with three doses of either Hexavac or Infanrix-Hexa during infancy.

METHODS

This open-label, randomised, controlled, four-arm study enrolled 410 healthy children aged 4-7 years who had received either Hexavac (n=201) or Infanrix-Hexa (n=209) at 3, 5 and 11 months of life. Children received a single intramuscular challenge dose of either hepatitis B vaccine, HBVaxPro (Hexavac, n=34; Infanrix-Hexa, n=28) or Engerix-B (Hexavac, n=167; Infanrix-Hexa, n=181). Hepatitis B surface antibody (anti-HBs) concentrations were measured before and 1 month after the challenge vaccine dose. The analysis was descriptive and no formal hypothesis was tested.

RESULTS

One month post-challenge, 91.2% of children in the Hexavac group (95% confidence interval [CI] 86.3, 94.8) and 98.0% (95% CI 94.9, 99.4) in the Infanrix-Hexa group had anti-HBs concentrations ≥10 mIU/ml (primary endpoint). In a post hoc analysis, most children with pre-challenge anti-HBs concentration <10 mIU/ml achieved anti-HBs concentrations ≥10 mIU/ml (Hexavac group, 85.3% [95% CI 77.6, 91.2]; Infanrix-Hexa group, 91.9% [95% CI 78.1, 98.3]). Both challenge vaccines were well tolerated.

CONCLUSIONS

These data suggest that immune memory persists for long-term (5 years) after a primary vaccination in infancy with a hexavalent vaccine (Hexavac or Infanrix-Hexa).

A randomised, double-blind, non-inferiority clinical trial on the safety and immunogenicity of a tetanus, diphtheria and monocomponent acellular pertussis (TdaP) vaccine in comparison to a tetanus and diphtheria (Td) vaccine when given as booster vaccinations to healthy adults

BACKGROUND

Increasing incidence of pertussis in adolescents and adults has stimulated the development of safe and immunogenic acellular pertussis vaccines for booster vaccination of adolescents and adults.

PURPOSE

To obtain clinical documentation of the safety and immunogenicity of a tetanus, diphtheria and monocomponent acellular pertussis combination vaccine (TdaP), when given as a booster vaccination to adults.

METHODS

The trial was double-blind, controlled and randomised. 802 healthy adults, aged 18-55 years who had completed childhood vaccination with diphtheria, tetanus and whole cell pertussis vaccine (DTwP), were booster vaccinated with TdaP or Td. Blood samples were taken before and one month after the vaccination for serological analysis and adverse events were recorded during the one-month-follow-up period.

RESULTS

The monocomponent acellular pertussis vaccine (aP) in the TdaP vaccine was immunogenic in adults with 92.0% of TdaP vaccinated subjects obtaining an anti-pertussis toxin (anti-PT) antibody booster response. TdaP was non-inferior to Td in eliciting seroprotective anti-tetanus and diphtheria antibody concentrations with more than 98% of subjects obtaining post-vaccination seroprotective concentrations (≥ 0.1 IU/mL). T and d booster response rates were 93.0% and 97.5%, respectively. The frequencies of solicited local adverse reactions were low and comparable between TdaP and Td vaccinees. In the TdaP group, 30.7% reported pain, 4.2% swelling and 2.0% erythema at the injection site. The most frequent solicited general symptoms were headache (20.4%), fatigue (17.0%) and myalgia (10.0%). In the Td group, 35.7% reported pain, 2.5% swelling and 3.2% erythema at the injection site, whereas headache, fatigue and myalgia were reported by 15.7%, 14.5% and 12.5%, respectively. In conclusion, TdaP Vaccine SSI was safe and immunogenic when given as a booster vaccination to adults.

An alternative approach to combination vaccines: intradermal administration of isolated components for control of anthrax, botulism, plague and staphylococcal toxic shock

BACKGROUND

Combination vaccines reduce the total number of injections required for each component administered separately and generally provide the same level of disease protection. Yet, physical, chemical, and biological interactions between vaccine components are often detrimental to vaccine safety or efficacy.

METHODS

As a possible alternative to combination vaccines, we used specially designed microneedles to inject rhesus macaques with four separate recombinant protein vaccines for anthrax, botulism, plague and staphylococcal toxic shock next to each other just below the surface of the skin, thus avoiding potentially incompatible vaccine mixtures.

RESULTS

The intradermally-administered vaccines retained potent antibody responses and were well- tolerated by rhesus macaques. Based on tracking of the adjuvant, the vaccines were transported from the dermis to draining lymph nodes by antigen-presenting cells. Vaccinated primates were completely protected from an otherwise lethal aerosol challenge by Bacillus anthracis spores, botulinum neurotoxin A, or staphylococcal enterotoxin B.

CONCLUSION

Our results demonstrated that the physical separation of vaccines both in the syringe and at the site of administration did not adversely affect the biological activity of each component.The vaccination method we describe may be scalable to include a greater number of antigens, while avoiding the physical and chemical incompatibilities encountered by combining multiple vaccines together in one product.

The effect of changing from whole-cell to acellular pertussis vaccine on the epidemiology of hospitalized children with pertussis in Canada

BACKGROUND

Between July 1997 and April 1998, universal childhood immunization programs in Canada changed from using a whole-cell pertussis to a 5-component acellular pertussis-containing vaccine. To assess effects on pertussis epidemiology of this nationwide change, we analyzed hospitalizations during 1991-2004 using the Canadian Immunization Monitoring Program, Active (IMPACT) pertussis database.

METHODS

IMPACT is an active surveillance network based in 12 pediatric tertiary-care hospitals across Canada. Characteristics of hospitalized cases of pertussis were compared by type of vaccine received or by birth date (if immunization records were unavailable or the child was unvaccinated). Age-stratified incidence rates were calculated by year and vaccine type.

RESULTS

Two thousand ninety-six cases of pertussis were admitted to IMPACT centers, 1174 during the whole-cell vaccine program (WCV-P) and 842 during the acellular vaccine program (ACV-P). Pertussis incidence among children <5 years old decreased significantly during the ACV-P, causing an increase in the residual proportion of cases either too young to be immunized (<2 months old: ACV-P 39% versus WCV-P 26.1%; P < 0.0001) or too young for a second dose (2-3 months old: 42.9% versus 34.2%, respectively; P < 0.0001). A significantly smaller proportion of cases (ACV-P 15.1% versus WCV-P 27.3%) occurred in infants who were old enough (4-11 months of age) to have received 2 or 3 doses of vaccine.

CONCLUSIONS

With ACV-P, pertussis hospitalizations in children 4-59 months old decreased in frequency, consistent with improved vaccine effectiveness, but remained prominent among very young infants. Improved control strategies are needed to reduce infections among infants too young for pertussis vaccination.

Booster immunization with a hexavalent diphtheria, tetanus, acellular pertussis, hepatitis B, inactivated poliovirus vaccine and Haemophilus influenzae type b conjugate combination vaccine in the second year of life: safety, immunogenicity and persistence of antibody responses

The immunogenicity and reactogenicity of booster vaccination with GSK Biologicals' hexavalent DTPa-HBV-IPV/Hib vaccine was assessed in toddlers aged 12-18 months previously primed with the same combination (N=341), or with DTPa-IPV/Hib and HBV administered separately (N=102; Trials 217744/059 and 217744/096). Antibody persistence at age 4-6 years was also assessed in children who had received a 4th consecutive dose of DTPa-HBV-IPV/Hib vaccine or separate DTPa-IPV/Hib and HBV vaccines in this study and in another study conducted under similar conditions in Germany. Prior to booster vaccination in the second year of life, antibody concentrations and seroprotection rates were similar irrespective of the primary vaccine used. One month after boosting with DTPa-HBV-IPV/Hib, substantial antibody increases were observed against all vaccine antigens indicative of previous immune priming. Seropositivity and booster response rates against all antigens were 97.4-100%. Reactogenicity following booster vaccination with DTPa-HBV-IPV/Hib was similar regardless of the primary regimen used. Three to four years after administration of the 4th DTPa-HBV-IPV/Hib dose, >90% vaccinees had persistent protective antibody concentrations against diphtheria, hepatitis B, Hib and the three poliovirus types. Anti-tetanus antibody concentrations were > or = 0.1 IU/ml in 76.4% subjects and seropositivity for pertussis antibodies ranged from 34.5% for PT to 98.9% for FHA. In conclusion, the combined hexavalent DTPa-HBV-IPV/Hib vaccine is immunogenic and safe when used for boosting in the second year of life, regardless of the primary vaccine used, and offers sustained protection during early childhood and beyond.

A comparison of booster immunisation with a combination DTPa-IPV vaccine or DTPa plus IPV in separate injections when co-administered with MMR, at age 4–6 years

This study evaluated GSK's combined DTPa-IPV vaccine (Infanrix-IPV) given as a fifth consecutive acellular pertussis booster dose in conjunction with the second dose of MMR vaccine (Priorix) in children aged 4-6 years. The immunogenicity and reactogenicity of this vaccine regimen was compared with separate injections of DTPa and IPV when given concomitantly with MMR. A cohort of 362 children previously primed with four doses of DTPa and OPV, and a single dose of MMR were randomized to receive either DTPa-IPV+MMR (N=181) or DTPa+IPV+MMR (N=181). Antibody concentrations were measured prior to and 1 month after the booster dose. After immunisation all subjects from both groups had seroprotective antibody levels against diphtheria, tetanus and the three poliovirus serotypes, > or = 96% showed vaccine response to PT, FHA and PRN, all were seropositive to mumps and rubella, and all but one subject were seropositive to measles. Immunogenicity results for each component antigen were similar for DTPa-IPV and separately co-administered DTPa and IPV. Local reactions were common with 24.0% and 31.1% of children experiencing swelling >50mm at the DTPa-IPV and DTPa injection sites, respectively. The DTPa-IPV combination did not increase the incidence or intensity of adverse events compared with separately administered DTPa+IPV. The response to the concomitantly administered MMR vaccine was similar in the two groups and similar to previously reported responses for a second dose of MMR. This combined DTPa-IPV vaccine has a similar reactogenicity profile to DTPa, is immunogenic when given as a booster dose at 4-6 years of age, and has no impact on the immunogenicity of a co-administered second dose of MMR vaccine.

Immunogenicity and reactogenicity of primary immunization with a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio-Haemophilus influenzae type B vaccine coadministered with two doses of a meningococcal C-tetanus toxoid conjugate vaccine

BACKGROUND

This study evaluated the concurrent use of meningococcal C tetanus conjugate (MenC-TT) vaccine (NeisVac-C) with DTaP-based combinations, according to 2 vaccination schedules, one of which included hepatitis B vaccination at birth (Trial DTaP-HBV-IPV/Hib-097).

METHODS

Healthy infants were randomized to receive either DTaP-HBV-IPV/Hib (Infanrix hexa) at 2, 4, and 6 months (N = 115) or HBV at birth followed by DTaP-HBV-IPV/Hib at 2 and 6 months and DTaP-IPV/Hib (Infanrix-IPV Hib) at 4 months (N = 115). In both groups 2 doses of MenC-TT conjugate were coadministered at 2 and 4 months, and compared with 3 doses of MenC-CRM197 conjugate (Meningitec) coadministered at 2, 4, and 6 months with DTaP-HBV-IPV/Hib (N = 120). Antibody concentrations were measured at 2, 6 and 7 months. Solicited local and general symptoms, unsolicited symptoms, and serious adverse events (SAEs) were recorded.

RESULTS

All MenC-TT recipients had seroprotective concentrations of anti-PRP antibodies (> or = 0.15 microg/mL) 1 month after the third vaccine dose and all had SBA-MenC titers > or = 1:8 after the second dose of MenC-TT. These responses were noninferior to those seen after 3 doses of DTaP-HBV-IPV/Hib and MenC-CRM. Anti-PRP antibody GMCs were significantly higher in MenC-TT than MenC-CRM vaccinees (7.9, 7.3, 3.8 microg/mL, respectively). Immune responses to all other coadministered antigens were unimpaired, with seroprotection/seropositivity rates > or = 98.1% in MenC-TT vaccinees. All schedules studied were well tolerated, with no differences in reactogenicity between the study groups.

CONCLUSIONS

Coadministration of DTaP-HBV-IPV/Hib or DTaP-IPV/Hib with 2 doses of MenC-TT conjugate vaccine is safe, well tolerated, and immunogenic, with no impairment of the response to the coadministered antigens.

Haemophilus influenzae type b reemergence after combination immunization

Combination vaccines may suppress Hib antibody concentration and avidity.

An increase in Haemophilus influenzae type b (Hib) in British children has been linked to the widespread use of a diphtheria/tetanus/acellular pertussis combination vaccine (DTaP-Hib). We measured anti-polyribosyl-ribitol phosphate antibody concentration and avidity before and after a Hib booster in 176 children 2–4 years of age who had received 3 doses of DTP-Hib (either DT whole cell pertussis-Hib or DTaP-Hib) combination vaccine in infancy. We also measured pharyngeal carriage of Hib. Antibody concentrations before and avidity indices after vaccination were low (geometric mean concentration 0.46 μg/mL, 95% confidence interval [CI] 0.36–0.58; geometric mean avidity index 0.16, 95% CI 0.14–0.18) and inversely related to the number of previous doses of DTaP-Hib (p = 0.02 and p<0.001, respectively). Hib was found in 2.1% (95% CI 0.7%–6.0%) of study participants. Our data support an association between DTaP-Hib vaccine combinations and clinical Hib disease through an effect on antibody concentration and avidity.

Live bivalent vaccine for parainfluenza and influenza virus infections

Influenza and human parainfluenza virus infections are of both medical and economical importance. Currently, inactivated vaccines provide suboptimal protection against influenza, and vaccines for human parainfluenza virus infection are not available, underscoring the need for new vaccines against these respiratory diseases. Furthermore, to reduce the burden of vaccination, the development of multivalent vaccines is highly desirable. Thus, to devise a single vaccine that would elicit immune responses against both influenza and parainfluenza viruses, we used reverse genetics to generate an influenza A virus that possesses the coding region for the hemagglutinin/neuraminidase ectodomain of parainfluenza virus instead of the influenza virus neuraminidase. The recombinant virus grew efficiently in eggs but was attenuated in mice. When intranasally immunized with the recombinant vaccine, all mice developed antibodies against both influenza and parainfluenza viruses and survived an otherwise lethal challenge with either of these viruses. This live bivalent vaccine has obvious advantages over combination vaccines, and its method of generation could, in principle, be applied in the development of a "cocktail" vaccine with efficacy against several different infectious diseases.

Comparison of the immunogenicity and reactogenicity of two commercially available hexavalent vaccines administered as a primary vaccination course at 2, 4 and 6 months of age

Infants (N = 459) were randomly assigned to receive either Infanrix hexa or Hexavac vaccines at 2, 4 and 6 months of age as a primary vaccination schedule. The immunogenicity of the hepatitis B component was statistically significantly higher for Infanrix hexa compared to Hexavac in terms of both seroprotection (98.6% versus 94.7%, p = 0.0302) and GMCs (905.6 versus 226.4, p < 0.0001). Significantly (p < or =0.0001) higher antibody levels against diphtheria and the 3 polio components were also induced by Infanrix hexa. The responses to tetanus, Hib and pertussis components were similar. The incidences of clinically relevant solicited symptoms, unsolicited symptoms or serious adverse events were low in both groups.

Booster vaccination with hexavalent DTPa-HBV-IPV/Hib vaccine in the second year of life is as safe as concomitant DTPa-IPV/Hib + HBV administered separately

The safety and reactogenicity of a booster dose of GSK Biologicals' hexavalent DTPa-HBV-IPV/Hib vaccine (N=4725) was compared with the separate administration of GSK Biologicals' DTPa-IPV/Hib and HBV vaccines (N=4474) in two open, randomized multicenter studies (A and B). Solicited symptoms occurring within 4 days of vaccination were recorded on diary cards and serious adverse events (SAEs) were collected throughout the study period. In Study A (N=1149), incidences of solicited symptoms were similar in both groups; there were no SAEs either reported within 4 days of vaccination or considered to be causally related to vaccination. In study B (N=8050), where fever was the only solicited symptom, rectal temperature > or =39.5 degrees C was observed in 2.5% and 2.8% of the subjects, respectively. Fever > or =40.0 degrees C was rare (0.6%), and only two cases of febrile convulsions were recorded during the 4 days following vaccination both in the control group. Large swelling reactions (defined as local injection site swelling with diameter >50 mm, noticeable diffuse injection site swelling or noticeable increased circumference of the injected limb) were reported following 2.3% of the booster vaccine doses, regardless of the vaccine used. Extensive swelling reactions involving an adjacent joint were reported in 0.1% of the subjects. Two SAEs, both reported after booster doses of DTPa-IPV/Hib and HBV vaccines administered separately, were considered by the investigators to be related to vaccination. Both resolved completely without sequelae. The hexavalent DTPa-HBV-IPV/Hib vaccine and the DTPa-IPV/Hib and HBV vaccines administered separately have similar good reactogenicity and safety profiles when given as booster doses in the second year of life.

Overcoming antigenic diversity and improving vaccines using DNA shuffling and screening technologies

Viral, bacterial and parasitic pathogens have evolved multiple strategies to evade the immune response, facilitate transmission and establish chronic infections. One of the underlying strategies that pathogens have evolved is antigenic variation of immune response targets that reduce the affinity of antigen binding to antibodies and major histocompatability complex class I and II receptors. Vaccine candidates generally target a limited number of these antigen variants or combine antigens from several variants to include in multivalent vaccine formulations. DNA shuffling and screening technologies, also known as MolecularBreeding (Maxygen, Inc.) directed molecular evolution, have been successfully used to identify and develop novel and chimaeric vaccine candidates capable of inducing immune responses that recognise and control multiple antigenic variants. DNA shuffling and screening strategies also select vaccine candidates with improved immunogenicity, increased expression as recombinant polypeptides and improved growth of whole viruses in cell culture. As DNA shuffling and screening strategies can be applied to many pathogens, there remain numerous applications of DNA shuffling to solve challenging problems in vaccine process development and manufacture.

Acellular pertussis vaccines for use among infants and young children

Pertussis is still one of the most common vaccine-preventable childhood diseases in developed countries. Infants, particularly those < 6 months, are the most susceptible and those who suffer the greatest disease burden and mortality. In the 1970s, concerns about the reactogenicity of whole-cell vaccines led to a decrease in vaccine coverage and later the re-emergence of the disease in many countries. The advent of acellular vaccines in recent years has constituted an important advance in the acceptance of this immunisation and consequently the control of the disease. The efficacy of acellular pertussis vaccines is approximately 59 - 93%, similar to whole-cell vaccines, but all available data confirm the substantial improvement in safety of the new vaccines. With the licensure of acellular pertussis vaccines and combined vaccines containing them, pertussis immunisation has become significantly developed. Furthermore, the possibility of continuing to vaccinate adolescents and adults with new diphtheria, tetanus, and pertussis (dTap) vaccines is an important step in achieving control and elimination of the disease.

Archaeosomes as adjuvants for combination vaccines

The present study evaluated the potential of archaesomes, prepared from the total polar lipids extracted from Methanobrevibacter smithii, as adjuvants for combination (multivalent) vaccines. Groups of Balb/c mice were immunized subcutaneously at day 0 and 21 with one of the following vaccines: trivalent vaccine formulated by the simultaneous co-encapsulation of bovine serum albumine (BSA), ovalbumin (OVA) and hen egg lysozyme (HEL) into archaeosomes (CEC vaccine); an univalent archaeosome vaccine (UVE vaccine) containing either BSA, OVA or HEL; or an admixture vaccine (AMC vaccine) consisting of the three UVE vaccines. Serum specific antibody (IgG + M) responses were determined at day 32, 112 and 203, and specific IgG1 and IgG2a responses were determined at day 112. Mice immunized with the CEC of AMC vaccine developed strong and sustained specific antibody responses to all three antigens at a magnitude similar to those seen in control mice immunized with UVE vaccines. Moreover, the serum BSA-, OVA-, and HEL-specific IgG1 and IgG2a levels in the CEC and AMC immunized mice were overall comparable to those of the UVE immunized control mice. Boosting CEC and AMC vaccinated mice with antigens alone at day 203 elicited strong antibody memory responses, comparable to those in the UVE vaccinated groups. These results show that archaeosomes could be used as adjuvants in developing combination vaccines.

Immunogenicity and reactogenicity of four doses of diphtheria-tetanus-three-component acellular pertussis-hepatitis B-inactivated polio virus-Haemophilus influenzae type b vaccine coadministered with 7-valent pneumococcal conjugate Vaccine

BACKGROUND

The 7-valent pneumococcal (7vPn) conjugate vaccine is licensed for primary and booster vaccination according to the same immunization schedules as routinely recommended diphtheria-tetanus-pertussis-based childhood vaccines and can be coadministered during the same vaccination visit.

METHODS

An open, randomized study evaluated the immunogenicity and safety of a hexavalent diphtheria-tetanus-acellular pertussis-hepatitis B-inactivated polio virus-Haemophilus influenzae type b (DTPa-HBV-IPV/Hib) vaccine and a 7vPn conjugate vaccine when coadministered at 2, 3 and 4 months and 12-23 months of age, compared with the administration of the hexavalent DTPa-HBV-IPV/Hib vaccine given alone. Serum antibody titers were measured before and 1 month after the primary course and before and 1 month after the booster dose. Solicited local and general adverse events were recorded for 4 days and unsolicited adverse events were recorded for 30 days after each vaccine dose.

RESULTS

A total of 345 subjects were enrolled for primary vaccination with the hexavalent vaccine (170 without and 175 with the 7vPn vaccine coadministered) and 266 returned for booster vaccination (122 without and 144 with coadministration of the 7vPn vaccine). After primary vaccination, antibody responses against the common antigens were similar in both groups, with seroprotection rates of 93.6-100% and with similar antibody decay before booster vaccination. The fourth dose induced a vigorous booster response, with seroprotection/vaccine response rates of 96.8-100%. Response to the 7vPn primary and booster vaccination was within previously reported ranges. Differences in reactogenicity resulted from higher incidences of symptoms after concomitant vaccination. Rectal temperature >39.5 degrees C was observed after 1.2% of the coadministered vaccine doses during primary vaccination and after 2.8% of the booster vaccine doses.

CONCLUSION

Coadministration of the DTPa-HBV-IPV/Hib and 7vPn vaccines at separate injection sites during the same vaccination visit was effective and safe.

Safety, reactogenicity and immunogenicity of a combined hexavalent tetanus, diphtheria, acellular pertussis, hepatitis B, inactivated poliovirus vaccine and Haemophilus influenzae type b conjugate vaccine, for primary immunization of infants

Safety, reactogenicity and immunogenicity of GSK Biologicals' hexavalent DTPa-HBV-IPV/Hib vaccine (Infanrix)hexa) was assessed when used for primary vaccination at 3, 4 and 5 months of age (N = 2163), compared to the separate administration of DTPa-IPV/Hib and HBV vaccines (N = 720). A similar safety and reactogenicity profile was demonstrated for both vaccine regimens, as well as a good immune response for all antigen components. By offering protection against six diseases in a series of single injections, the hexavalent DTPa-HBV-IPV/Hib vaccine was shown to be a safe, well tolerated and immunogenic alternative to primary immunization with licensed separately administered vaccines.