Pneumococcal conjugate vaccine serotypes of Streptococcus pneumoniae isolates and the antimicrobial susceptibility of such isolates in children with otitis media.
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The ability of the recently licensed 7-valent pneumococcal conjugate vaccine to cover isolates that cause otitis media, especially drug-resistant ones, was assessed using 500 recently obtained US isolates. Of these isolates, 418 (84%) belonged to vaccine-related serogroups, whereas 82 (16%) belonged to non-vaccine-related serogroups. Serotype 3 accounted for 48 (59%) of the non-vaccine-related serogroups. In addition, 93% of the isolates from patients < or =3 years of age belonged to serotypes that were included in or related to the heptavalent vaccine, compared with 49% of the isolates from older patients (P=.001). Most of the isolates (98%-100%) that were resistant to the antimicrobial agents tested were covered by the heptavalent vaccine, including 95.1% of the isolates from patients <2 years of age. The 7-valent pneumococcal conjugate vaccine could therefore potentially provide protection against all but 1 (type 3) of the common otitis media-associated pneumococcal serogroups identified in this study as well as against 98% of antibiotic-resistant isolates. (+info)
Activity and cross-reactivity of antibodies induced in mice by immunization with a group B meningococcal conjugate.
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The capsular polysaccharide of group B Neisseria meningitidis is composed of a linear homopolymer of alpha(2-8) N-acetyl neuraminic acid or polysialic acid (PSA) that is also carried by isoforms of the mammalian neural cell adhesion molecule (NCAM), which is especially expressed on brain cells during development. Here we analyzed the ability of antibodies induced by the candidate vaccine N-propionyl polysaccharide tetanus toxoid conjugate to recognize PSA-NCAM. We hyperimmunized mice to produce a pool of antisera and a series of immunoglobulin G monoclonal antibodies and evaluated their self-reactivity profile by using a battery of tests (immunoprecipitation, immunoblotting, and immunofluorescence detection on live cells and human tissue sections) chosen for their sensitivity and specificity to detect PSA-NCAM in various environments. We also searched for the effects of the vaccine-induced antibodies in two functional assays involving cell lysis or cell migration. Although they were highly bactericidal, all the antibodies tested showed very low or no recognition of PSA-NCAM, in contrast to PSA-specific monoclonal antibodies used as controls. Different patterns of cross-reactions were revealed by the tests used, likely due to affinity and specificity differences among the populations of induced antibodies. Furthermore, neither cell lysis nor perturbation of migration was observed in the presence of the tested antibodies. Importantly, we showed that whereas enzymatic removal of PSA groups from the surfaces of live cells perturbed their migration, blocking them with PSA-specific antibodies was not functionally detrimental. Taken together, our data indicated that this candidate vaccine induced antibodies that could not demonstrate an immunopathologic effect. (+info)
Safety of a new conjugate meningococcal C vaccine in infants.
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BACKGROUND: Group C conjugate meningococcal vaccines (Men C) were introduced into the UK primary immunisation schedule in November 1999. There has been extensive professional and public interest in their efficacy and safety. AIM: To determine the occurrence of at least one uncommon adverse event in infants related to the administration of the Chiron Men C vaccine. METHODS: A total of 2796 infants aged approximately 2 months were recruited into the study from areas in and around Sheffield and from Scotland. They were vaccinated with the Chiron Men C vaccine at 2, 3, and 4 months along with routine immunisations. Data on adverse events occurring one month after each dose were collected actively and prospectively and reviewed for possible relation to the vaccine. RESULTS: There were no deaths. There were no serious adverse events considered definitely or probably caused by the vaccine. Four infants developed serious adverse events (hypotonia, screaming syndrome, maculopapular rash, and agitation, respectively) that were considered possibly related to the vaccine. All recovered completely. Adverse events were seen in 1804 children but were considered possibly related to the vaccine in only 49 (1.8%). On subsequent immunisation there were no recurrences of adverse events considered to be possibly related to the vaccine. (+info)
Development, acceptance, and use of immunologic correlates of protection in monitoring the effectiveness of combination vaccines.
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The establishment of immunologic correlates of protection for all vaccine antigens is a worthwhile goal. It allows new vaccines to be licensed on the basis of attainment of defined immunologic benchmarks, without the need for large-scale efficacy trials for each new product. This is particularly important for the evaluation of new combination products. Efficacy trials of each new mixture would be unethical because routinely recommended vaccines would be denied children in the control group. The establishment of immunologic correlates of protection should be a defined goal of every efficacy trial. Additional ways to evaluate the immune responses-such as cell-mediated immunity, mucosal immunity, memory responses, and antibody avidity-should also be studied. Finally, ongoing surveillance efforts are also needed, to monitor the impact of new and combined vaccines on disease rates. (+info)
Perspectives on the design and analysis of prelicensure trials: bridging the gap to postlicensure studies.
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Recently, there has been growing concern regarding vaccine safety. Vaccines have led to the eradication of many serious diseases. Accordingly, there is less familiarity with the consequences of diseases and increasing concern with potential rare adverse events. The availability of clinical information systems within health maintenance organizations makes assessment of safety in larger cohorts, with power to assess rare adverse events, possible. However, no trial, no matter how large, can rule out all possible adverse events. There will always be the possibility that a rarer adverse event-just beyond the power of detection of a given trial-may occur. It is proposed that prelicensure trials in 10,000-40,000 children are now feasible. However, it will be necessary to develop an analytic continuum in which prelicensure studies are followed up with postmarketing assessments. Accordingly, the rapid identification of intussusception as a complication of rotavirus vaccination should not be seen as a failure of prelicensure studies but rather as a positive example of an effective integrated safety assessment program. (+info)
Meningococcal disease and travel.
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Invasive meningococcal disease, in both endemic and epidemic forms, is the cause of significant morbidity and mortality worldwide. Despite all advances in therapy, the fatality rate of meningococcal meningitis remains unacceptably high, between 5% and 10%, and a similar proportion suffers long-term neurological sequalae. Prevention of this rapidly fatal disease is of paramount importance. The use of the available internationally licensed meningococcal vaccines would be indicated for individuals with medical conditions that increase the risk of the disease and for travelers to high-risk countries. In the last 2 years, there has been a shift in the epidemic pattern of meningococcal disease during the Hajj (pilgrimage) season, with predominance of Neisseria meningitidis serogroup W135. Recent changes have been made in the policy issued by the Saudi Ministry of Health (Riyadh, Saudi Arabia), which requires visitors from all over the world arriving for purposes of umra and Hajj to show evidence of vaccination against meningitis with the quadrivalent meningococcal vaccine. (+info)
Analysis of the ontogeny of the murine humoral response to Neisseria meningitidis B capsular polysaccharide reveals levels of complexity relevant to vaccine development.
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Although purified capsular polysaccharide of Neisseria meningitidis group B (CpsB) is not immunogenic at any age, CpsB on the bacterial surface elicits antibody responses late in ontogeny. Therefore, a detailed analysis of the ontogeny of the murine anti-CpsB response to N. meningitidis could determine key parameters regarding the poor immunogenicity of CpsB. The effects of bacterial dose, hyperimmunization, age, and sex on the induction of primary and secondary anti-CpsB immunoglobulin isotype profiles were studied. It was demonstrated that the timing and repetition of immunization and of the bacterial dose have a marked differential effect on the primary induction of anti-CpsB immunoglobulin isotypes and on the ability to induce anti-CpsB antibody responses after subsequent rechallenge. It is noteworthy that the ontogeny of the response is related to the appearance of natural anti-CpsB antibodies, but this is not associated with the presence of CpsB cross-reactive antigens in the microflora. (+info)
Immune response of premature infants to meningococcal serogroup C and combined diphtheria-tetanus toxoids-acellular pertussis-Haemophilus influenzae type b conjugate vaccines.
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To determine the immune response of premature infants to meningococcal serogroup C capsular polysaccharide (MCC) and combined diphtheria-tetanus toxoids-acellular pertussis-Haemophilus influenzae type b (DTaP-Hib) conjugate vaccines, 105 infants born at <32 weeks' gestation had Hib IgG geometric mean concentrations (GMCs) and MCC serum bactericidal antibody (SBA) geometric mean titers (GMTs) measured 1 month after the third immunization. Term infants served as control subjects. Premature infants had Hib GMCs of 0.27 microg/mL, with 21% achieving GMCs >1.0 microg/mL, compared with 0.81 microg/mL and 46% in term infants (P<.001 and P=.003, respectively). The MCC SBA GMT was 398, with 99% achieving an SBA > or =8, compared with 380 and 98% in term infants (P=.84 and P=1.0, respectively). Hib IgG was associated with age at third immunization (P<.001). When combined with the DTaP vaccine used in this study, the Hib GMC of premature infants was extremely low. The SBA GMT to MCC was similar to that of term infants. (+info)