The development of a new heptavalent diphtheria–tetanus–whole cell pertussis–hepatitis B–Haemophilus influenzae type b–Neisseria meningitidis serogroups A and C vaccine: a randomized dose-ranging trial of the conjugate vaccine components

The immunogenicity and safety of a Hib-MenAC vaccine: a non-inferiority randomized, observer-blind trial in infants aged 3-5 months

BACKGROUND

The objective of this study was to evaluate the immunogenicity and safety of the novel combined Haemophilus influenzae type b-Neisseria meningitidis serogroup A and C-tetanus toxoid conjugate vaccine (Hib-MenAC).

METHODS

We conducted a non-inferiority, randomized, observer-blind, positive control clinical trial in 900 healthy infants aged between 3-5 months in Funing County, Jiangsu Province, China. Participants were randomly allocated, in a ratio of 2:1 (block = 6), to receive experimental combined Hib-MenAC vaccines co-administrated with placebo or the co-administration of licensed Hib vaccine and MenAC vaccine, according to a three-dose immunization schedule. The seroconversion of antibody titer against meningococcal serogroups A, C and Hib was the primary endpoint.

RESULTS

The experimental vaccines was non-inferior to the licensed two control vaccines. Participants receiving experimental Hib-MenAC vaccines showed a seroconversion rate of 99.0%, 96.1% and 97.7% for rSBA-MenA, rSBA-MenC and anti-PRP antibodies, respectively. The Hib-MenAC vaccine did not result in an increase in adverse reaction, and no serious adverse event was judged to be related to the vaccination.

CONCLUSIONS

The novel combined Hib-MenAC conjugate vaccine was safe and highly immunogenic in infants aged between 3 to 5 months.

A multi-criteria decision making approach to identify a vaccine formulation

This article illustrates the use of a multi-criteria decision making approach, based on desirability functions, to identify an appropriate adjuvant composition for an influenza vaccine to be used in elderly. The proposed adjuvant system contained two main elements: monophosphoryl lipid and α-tocopherol with squalene in an oil/water emulsion. The objective was to elicit a stronger immune response while maintaining an acceptable reactogenicity and safety profile. The study design, the statistical models, the choice of the desirability functions, the computation of the overall desirability index, and the assessment of the robustness of the ranking are all detailed in this manuscript.

Safety and immunogenocity of a novel combined Haemophilus influenzae type b-Neisseria meningitidis serogroups A and C-tetanus-toxoid conjugate vaccine in healthy Chinese children aged 6 months to 5 years old

A novel combined Haemophilus influenzae type b-Neisseria meningitidis serogroups A and C-tetanus-toxoid conjugate vaccine (Hib-MenAC vaccine) has been developed to protect children against diseases caused by Hib, MenA, and MenC. This study investigated the safety and immunogenicity of the Hib-MenAC vaccine administered in 2-dose series to children aged 6-23 months and in a single dose to children aged 2-5 y. A randomized, positive-controlled, non-inferiority clinical trial was conducted for 1200 healthy participants in each age group. Within each age group, participants were randomly allocated to the Hib-MenAC group or the control group at a ratio of 1:1. Adverse reactions were recorded within 28 d after each dose. Blood samples were obtained to assess immunogenicity on day 0 and at 28 d after a complete vaccination course. For the investigational vaccine, the incidence of total adverse reactions in vaccinees aged 6-23 months was 46.8% and that in vaccinees aged 2-5 y was 29.8%. Most adverse reactions were mild or moderate. One non-fatal serious adverse event occurred in the Hib-MenAC group, but was unrelated to vaccination. The seroconversion rate to the 3 components reached 94.0%, and the proportion of vaccinees with rSBA titers ≥ 1:8 and PRP ≥ 0.15 g/mL reached 97.0% in both age groups. The safety and immunogenicity of the Hib-MenAC vaccine were non-inferior when compared to the licensed vaccines. It was concluded that the novel vaccine would be expected to protect children against all of the targeted diseases.

Vaccination in Southeast Asia--reducing meningitis, sepsis and pneumonia with new and existing vaccines

Streptococcus pneumoniae, Haemophilus influenzae type b and Neisseria meningitidis are leading causes of vaccine-preventable diseases such as meningitis, sepsis and pneumonia. Although there has been much progress in the introduction of vaccines against these pathogens, access to vaccines remains elusive in some countries. This review highlights the current S. pneumoniae, H. influenzae type b, and N. meningitidis immunization schedules in the 10 countries belonging to the Association of Southeast Asian Nations (ASEAN). Epidemiologic studies may be useful for informing vaccine policy in these countries, particularly when determining the cost-effectiveness of introducing new vaccines.

Conjugate Meningococcal Vaccines Development: GSK Biologicals Experience

Meningococcal diseases are serious threats to global health, and new vaccines specifically tailored to meet the age-related needs of various geographical areas are required. This paper focuses on the meningococcal conjugate vaccines developed by GSK Biologicals. Two combined conjugate vaccines were developed to help protect infants and young children in countries where the incidence of meningococcal serogroup C or serogroup C and Y disease is important: Hib-MenC-TT vaccine, which offers protection against Haemophilus influenzae type b and Neisseria meningitidis serogroup C diseases, is approved in several countries; and Hib-MenCY-TT vaccine, which adds N. meningitidis serogroup Y antigen, is currently in the final stages of development. Additionally, a tetravalent conjugate vaccine (MenACWY-TT) designed to help protect against four meningococcal serogroups is presently being evaluated for global use in all age groups. All of these vaccines were shown to be highly immunogenic and to have clinically acceptable safety profiles.

Measurement of functional anti-meningococcal serogroup a activity using strain 3125 as the target strain for serum bactericidal assay

Functional anti-N. meningitidis serogroup A (MenA) activity in human serum is detected by serum bactericidal assay (SBA), using either rabbit (rSBA) or human (hSBA) complement, with F8238 as the recommended MenA SBA target strain. However, the F8238 strain may not be optimal for this purpose because, as we show here, it expresses the L11 immunotype, whereas most MenA invasive strains express the L(3,7)9 or L10 immunotype. Moreover, SBA results may be strain dependent, because immunotypes differ in their sensitivity to complement, emphasizing the need to choose the most appropriate strain. Sera from random subsets of infants, toddlers, children, and adolescents in clinical trials of MenA conjugate vaccines were tested by rSBA using strains 3125 (L10) and F8238 (L11). In unvaccinated subjects from all age groups, the percentages of seropositive samples (rSBA-MenA titer, ≥1:8) was lower using strain 3125 than using strain F8238. However, in toddlers and adolescents immunized with a conjugate MenA vaccine, the percentages of seropositive samples generally were similar using either strain in the rSBA. In two studies, sera also were tested with hSBA. Using hSBA, the differences in the percentages of seroprotective samples (hSBA-MenA titer, ≥1:4) between strains 3125 and F8238 was less apparent, and in contrast with rSBA, the percentage of seroprotective samples from unvaccinated subjects was slightly higher using strain 3125 than using strain F8238. In adults vaccinated with plain MenA polysaccharide, the percentage of seroprotective samples was higher using strain 3125 than with strain F8238, and the vaccine response rates using strain 3125 were better aligned with the demonstrated efficacy of MenA vaccination. In conclusion, SBA results obtained using the MenA L10 3125 strain better reflected vaccine-induced immunity.

An evaluation of emerging vaccines for childhood meningococcal disease

Background

Meningococcal meningitis is a major cause of disease worldwide, with frequent epidemics particularly affecting an area of sub-Saharan Africa known as the “meningitis belt”. Neisseria meningitidis group A (MenA) is responsible for major epidemics in Africa. Recently W-135 has emerged as an important pathogen. Currently, the strategy for control of such outbreaks is emergency use of meningococcal (MC) polysaccharide vaccines, but these have a limited ability to induce herd immunity and elicit an adequate immune response in infant and young children. In recent times initiatives have been taken to introduce meningococcal conjugate vaccine in these African countries. Currently there are two different types of MC conjugate vaccines at late stages of development covering serogroup A and W-135: a multivalent MC conjugate vaccine against serogroup A,C,Y and W-135; and a monovalent conjugate vaccine against serogroup A. We aimed to perform a structured assessment of these emerging meningococcal vaccines as a means of reducing global meningococal disease burden among children under 5 years of age.

Methods

We used a modified CHNRI methodology for setting priorities in health research investments. This was done in two stages. In the first stage we systematically reviewed the literature related to emerging MC vaccines relevant to 12 criteria of interest. In Stage II, we conducted an expert opinion exercise by inviting 20 experts (leading basic scientists, international public health researchers, international policy makers and representatives of pharmaceutical companies). They answered questions from CHNRI framework and their “collective optimism” towards each criterion was documented on a scale from 0 to 100%.

Results

For MenA conjugate vaccine the experts showed very high level of optimism (~ 90% or more) for 7 out of the 12 criteria. The experts felt that the likelihood of efficacy on meningitis was very high (~ 90%). Deliverability, acceptability to health workers, end users and the effect on equity were all seen as highly likely (~ 90%). In terms of the maximum potential impact on meningitis disease burden, the median potential effectiveness of the vaccines in reduction of overall meningitis mortality was estimated to be 20%; (interquartile range 20-40% and min. 8%, max 50 %). For the multivalent meningococcal vaccines the experts had similar optimism for most of the 12 CHNRI criteria with slightly lower optimism in answerability and low development cost criteria. The main concern was expressed over the cost of product, its affordability and cost of implementation.

Conclusions

With increasing recognition of the burden of meningococcal meningitis, especially during epidemics in Africa, it is vitally important that strategies are taken to reduce the morbidity and mortality attributable to this disease. Improved MC vaccines are a promising investment that could substantially contribute to reduction of child meningitis mortality world-wide.

Neonatal and infantile immune responses to encapsulated bacteria and conjugate vaccines

Encapsulated bacteria are responsible for the majority of mortality among neonates and infants. The major components on the surface of these bacteria are polysaccharides which are important virulence factors. Immunity against these components protects against disease. However, most of the polysaccharides are thymus-independent (TI)-2 antigens which induce an inadequate immune response in neonates and infants. The mechanisms that are thought to play a role in the unresponsiveness of this age group to TI-2 stimuli will be discussed. The lack of immune response may be overcome by conjugating the polysaccharides to a carrier protein. This transforms bacterial polysaccharides from a TI-2 antigen into a thymus-dependent (TD) antigen, thereby inducing an immune response and immunological memory in neonates and infants. Such conjugated vaccines have been shown to be effective against the most common causes of invasive disease caused by encapsulated bacteria in neonates and children. These and several other approaches in current vaccine development will be discussed.

A phase II, randomized study on an investigational DTPw-HBV/Hib-MenAC conjugate vaccine administered to infants in Northern Ghana

BACKGROUND

Combining meningococcal vaccination with routine immunization in infancy may reduce the burden of meningococcal meningitis, especially in the meningitis belt of Africa. We have evaluated the immunogenicity, persistence of immune response, immune memory and safety of an investigational DTPw-HBV/Hib-MenAC conjugate vaccine given to infants in Northern Ghana.

METHODS AND FINDINGS

In this phase II, double blind, randomized, controlled study, 280 infants were primed with DTPw-HBV/Hib-MenAC or DTPw-HBV/Hib vaccines at 6, 10 and 14 weeks of age. At 12 months of age, children in each group received a challenge dose of serogroup A+C polysaccharides. Antibody responses were assessed pre, and one month-post dose 3 of the priming schedule and pre and 1 month after administration of the challenge dose. One month post-dose 3, 87.8% and 88.2% of subjects in the study group had bactericidal meningococcal serogroup A (SBA-MenA) and meningococcal serogroup C (SBA-MenC) antibody titres > or = 1:8 respectively. Seroprotection/seropositivity rates to the 5 antigens administered in the routine EPI schedule were non-inferior in children in the study group compared to those in the control group. The percentages of subjects in the study group with persisting SBA-MenA titres > or = 1:8 or SBA-MenC titres > or = 1:8 at the age of 12 months prior to challenge were significantly higher than in control group (47.7% vs 25.7% and 56.4% vs 5.1% respectively). The administration of 10 microg of serogroup A polysaccharide increased the SBA-MenA GMT by 14.0-fold in the DTPW-HBV/HibMenAC-group compared to a 3.8 fold increase in the control-group. Corresponding fold-increases in SBA-MenC titres following challenge with 10 microg of group C polysaccharide were 18.8 and 1.9 respectively. Reactogenicity following primary vaccination or the administration of the challenge dose was similar in both groups, except for swelling (Grade 3) after primary vaccination which was more frequent in children in the vaccine than in the control group (23.7%; 95%CI [19.6-28.1] of doses vs 14.1%; 95% CI [10.9-17.8] of doses). Fifty-nine SAEs (including 8 deaths), none of them related to vaccination, were reported during the entire study.

CONCLUSIONS

Three dose primary vaccination with DTPw-HBV/Hib-MenAC was non-inferior to DTPw-HBV/Hib for the 5 common antigens used in the routine EPI schedule and induced bactericidal antibodies against Neisseria meningitidis of serogroups A and C in the majority of infants. Serogroup A and C bactericidal antibody levels had fallen below titres associated with protection in nearly half of the infants by the age of 12 months confirming that a booster dose is required at about that age. An enhanced memory response was shown after polysaccharide challenge. This vaccine could provide protection against 7 important childhood diseases (including meningococcal A and C) and be of particular value in countries of the African meningitis belt.

TRIAL REGISTRATION

Controlled-Trials.com ISRCTN35754083.