Systematic Review and Meta-Analysis of the Incidence of Myocarditis and Guillain-Barré Syndrome in Adolescents Receiving COVID-19 mRNA Vaccine
Bibliographic record
Abstract
This study aimed to evaluate the incidence and risk of rare long-term adverse events, specifically myocarditis and Guillain-Barré syndrome (GBS), in adolescents (12-19 years) following COVID-19 mRNA vaccination. We systematically searched MEDLINE, Embase, Cochrane CENTRAL, and Scopus, supplemented by trial registries and reference lists (PROSPERO: CRD420251045173). Eligible studies included randomized controlled trials (RCTs), cohort studies, case-control studies, self-controlled case series, and pharmacovigilance database analyses reporting myocarditis or GBS outcomes in adolescents receiving BNT162b2 or mRNA-1273. The search was conducted in June 2025, and all published studies were included. Risk of bias was assessed using the Cochrane RoB-2 tool, Newcastle-Ottawa Scale, or adapted criteria for pharmacovigilance studies. Effect measures were expressed as incidence rate or incidence rate ratios (IRRs) with 95% confidence intervals (CIs). Meta-analyses were conducted using random-effects models. Ten studies met the inclusion criteria. Myocarditis incidence was elevated in adolescent and young adult males, particularly after the second dose. Pooled analyses indicated a higher risk with mRNA-1273 compared to BNT162b2 (pooled IRR ≈ 3.9), although heterogeneity was very high (I² > 95%). For GBS, global pharmacovigilance data suggested only a modest association with mRNA vaccines (ROR 9.66), substantially weaker than for adenoviral vector or influenza vaccines. COVID-19 mRNA vaccination in adolescents is associated with a small but measurable increased risk of myocarditis, particularly in males, after the second dose, with a higher incidence following mRNA-1273. No consistent evidence of increased GBS risk was observed. Absolute risks remain low, and outcomes are generally favorable compared to SARS-CoV-2 infection. Continued surveillance and long-term follow-up are warranted.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.015 | 0.039 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.024 | 0.039 |
| Bibliometrics | 0.008 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.004 | 0.002 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".