Aluminium adjuvants in vaccines and potential health effects: systematic review

OBJECTIVE: To systematically review and critically appraise human evidence on potential health effects of aluminium adjuvanted vaccines. DESIGN: Systematic review following PRISMA (preferred reporting items for systematic review and meta-analysis) 2020 guidelines. DATA SOURCES: Six 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 STUDIES: Human 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 SYNTHESIS: Two 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). RESULTS: The 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 (