Meningococcal polysaccharide A and C vaccine powder and solvent for solution for injection vials

BackgroundAcute lymphoblastic leukemia is the most prevalent childhood cancer and the leading cause of cancer mortality before the age of 20. Although therapeutic advances have significantly improved survival, children and adolescents treated for acute lymphoblastic leukemia remain vulnerable to infections, largely preventable by vaccination, due to humoral and cellular immune dysfunction induced by disease and treatment.Materials and methodsThis systematic review, based on electronic databases, aims to evaluate antibody levels associated with potential protective immunity against vaccine antigens for diphtheria, pertussis, tetanus, poliomyelitis, Haemophilus influenzae type b, measles, mumps, rubella, influenza, varicella-zoster virus, yellow fever, pneumococcal, and meningococcal diseases in children and adolescents treated for acute lymphoblastic leukemia after completion of chemotherapy.ResultsA total of twenty-four studies published between 1981 and 2023 were included, comprising 1110 children and adolescents. Protective antibody levels ranged from 11% to 97% for diphtheria, 0% to 90% for pertussis, 20% to 100% for tetanus, and 11% to 95% for poliomyelitis. Haemophilus influenzae type b, protection ranged from 16.7% to 100%. Viral vaccines also showed heterogeneous responses, with protection rates of 25-79% for mumps, 16-86% for measles, 35-98% for rubella, and 23-75% for varicella-zoster virus. Antibody responses to pneumococcal and meningococcal vaccines were consistently low, with protection rates of 5-38% for pneumococcal studies and 12% in a single meningococcal study.ConclusionsThis review found a consistent and clinically relevant loss of vaccine-induced immunity in children and adolescents treated for acute lymphoblastic leukemia. The recommendation of vaccine booster doses for this vulnerable population, irrespective of serological status, may represent a more practical approach to ensuring adequate post-chemotherapy treatment protection.

Abstract licence: CC BY

BackgroundIn Canada, the burden of gonorrhea has been increasing steadily over the last decade with emerging multi-drug-resistant strains. There is a high genomic similarity between Neisseria meningitidis and Neisseria gonorrhoea.MethodsReview of published studies and on-going trials with the four-component meningococcal serogroup B vaccine (4CMenB-Bexsero®).ResultsObservational studies have shown protection against gonorrhea infection ranging from 35% to 59% for up to three years after the administration of 4CMenB. Several randomized clinical trials are also under way. Results from the DOXYVAC trial have been published but the sample size was too small to exclude a protective effect in the 30%-50% range. Recommendations on the use of 4CMenB for individuals at high risk of gonorrhea infection have been issued in the United Kingdom and New York state based on results of observational studies.ConclusionIf results of observational studies are confirmed by randomized trials with an acceptable cost-effectiveness profile in the Canadian context, a targeted immunization program using 4CMenB could be implemented.

Abstract licence: CC BY

IntroductionThe immunogenicity and safety of MenACYW-TT (MenQuadfi®) were compared to another quadrivalent meningococcal conjugate vaccine, MCV4-TT (Nimenrix®), when administered in infants alongside routine childhood vaccines in Europe.MethodsOne set of healthy infants was randomized 1:1 to receive MenACYW-TT (group 1; n = 714) or MCV4-TT (group 2; n = 726) at age 2, 4, and 12-18 months (2 + 1 regimen) concomitantly with routine vaccines (including 10-valent pneumococcal conjugate vaccine). Another set was randomized 1:1 to receive MenACYW-TT in a 2 + 1 regimen (group 3; n = 112) or a 3 + 1 regimen at age 2, 4, 6, and 12-18 months (group 4; n = 108) concomitantly with routine vaccines (including 13-valent pneumococcal conjugate vaccine). Immune responses against meningococcal serogroups A, C, W, and Y were measured by serum bactericidal assay using human complement (hSBA). Non-inferiority of MenACYW-TT versus MCV4-TT was based on hSBA geometric mean titers (GMTs) 30 days post-booster (dose 3; primary endpoint) and rates of seroprotection 30 days post-dose 2 (secondary endpoint) against all vaccine meningococcal serogroups. Immune responses to co-administered vaccines and safety were also assessed. Post hoc, non-inferiority of MenACYW-TT was also assessed based on seroresponse rates 30 days post-booster.ResultsNon-inferiority of MenACYW-TT versus MCV4-TT, based on GMTs post-booster, was demonstrated for serogroups C, W, and Y but not for A. GMTs against serogroups C, W, and Y were 1.5- to 4.5-fold higher with MenACYW-TT than MCV4-TT; those against serogroup A were marginally lower. Antibody responses in groups 3 and 4 against all serogroups were similar to group 1. Non-inferiority of MenACYW-TT based on seroresponse rates post-booster against all serogroups was demonstrated post hoc. No interference with concomitant routine vaccines nor safety concerns were identified.ConclusionsConsideration of all immunogenicity and safety data generated in this study supports the incorporation of MenACYW-TT into the routine childhood vaccination schedule as a 2 + 1 regimen starting at age 6 weeks.ClinicaltrialsGov identifierNCT03547271.

Abstract licence: CC BY-NC