Haemophilus type b conjugate vaccine solution for injection 0.5ml vials

ObjectiveTo systematically review and critically appraise human evidence on potential health effects of aluminium adjuvanted vaccines.DesignSystematic review following PRISMA (preferred reporting items for systematic review and meta-analysis) 2020 guidelines.Data sourcesSix databases and trial registries were searched from inception to 3 March 2023 then updated to 27 November 2025. Reference lists of eligible studies were also screened.Eligibility criteria for selecting studiesHuman studies assessing health outcomes after aluminium adjuvanted vaccination, including randomised controlled trials, cohort studies, case series, and ecological studies. Investigational vaccines, case reports, and review articles were excluded.Data extraction and synthesisTwo reviewers screened studies (with AI assistance for the 2023-25 update), extracted data, and assessed risk of bias (using RoB 2.0, ROBINS-I, or an adapted tool for case series). Certainty of evidence was rated using GRADE (Grading of Recommendations Assessment, Development, and Evaluation).ResultsThe review included 59 studies (37 case series, 11 randomised controlled trials, nine cohort studies, two ecological studies). High quality evidence from randomised controlled trials and large cohorts consistently showed no association between aluminium adjuvanted vaccines and serious or long term health outcomes, such as asthma, autism spectrum disorders, or other chronic conditions. Studies on macrophagic myofasciitis were generally small and methodologically limited, and did not provide credible evidence of a causal association (very low certainty). Localised persistent nodules or granulomas were observed infrequently after diphtheria-tetanus-pertussis vaccines, consistent with delayed type hypersensitivity (ConclusionsCurrent evidence does not support causal associations between aluminium adjuvanted vaccines and serious or long term health outcomes. The most consistently documented reactions were persistent nodules or granulomas that are uncommon, local, and self-limited hypersensitivity reactions. These findings are broadly consistent with post-licensure surveillance findings. The predominance of methodologically limited studies for some outcomes highlights the need for higher quality research.Systematic review registrationPROSPERO CRD42023462831.

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Background/Objectives: Re-emergence of Haemophilus influenzae serotype b (Hib) was reported in several European countries. We aimed to characterize the age distribution of H. influnezae carriage before and after Hib vaccination. Methods: We conducted a systematic review and meta-analysis to reassess H. influenzae carriage dynamics in the pre- and post-Hib vaccination eras, focusing on age-specific patterns in childhood. Searches were performed with no date restriction and included PubMed/MEDLINE, Scopus, Web of Science, WHO Global Index Medicus, and the Cochrane Library. Eligible studies reported nasopharyngeal and/or oropharyngeal carriage prevalence and serotype distribution. Pooled estimates with 95% confidence intervals (CIs) were calculated using random-effects models, with age-stratified analyses. Results: Twenty-two studies were included (12 pre- and 10 post-Hib vaccination). Pre-vaccination, pooled H. influenzae carriage prevalence was 24.3% (95% CI, 18.9-30.7%), including 6% (95% CI, 3.4-12.8%) for Hib and 17.5% (95% CI, 12.6-23.9%) for non-type b strains. Post-vaccination, overall carriage remained similar (21.8%; 95% CI, 14.6-31.2%), but Hib carriage declined markedly to 0.67% (95% CI, 0.26-1.71%), while non-type b strains predominated (16.7%; 95% CI, 10.4-25.6%). Meta-analysis showed that carriage peaked around 4-5 years of age and persisted into later childhood. Conclusions: Hib vaccination has reduced Hib carriage, but overall H. influenzae carriage persists due to non-type b strains. Age-related persistence of carriage may have implications for herd protection, particularly in the context of evolving vaccination schedules with early childhood boosters. Continued surveillance integrating carriage and immunological data is needed to inform optimization of vaccination strategies.

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