Active Surveillance for Myocarditis and Pericarditis in Canadian Children from 2021 to 2022: A Canadian Immunization Monitoring Program ACTive Study
Bibliographic record
Abstract
OBJECTIVE: To compare characteristics of children assessed at Canadian Immunization Monitoring Program Active (IMPACT) centers for myocarditis, myopericarditis, and pericarditis according to COVID-19 vaccination status, and to evaluate the association with vaccination. STUDY DESIGN: IMPACT conducted active surveillance for myocarditis, myopericarditis, and pericarditis by monitoring admission lists and diagnostic codes for children ≤16 years of age assessed in emergency departments or hospitalized with these conditions (June 2021 through December 2022). Clinical details and immunization histories were entered in an electronic database. Characteristics of cases meeting Brighton Collaboration case definitions for myocarditis and/or pericarditis were compared between COVID-19 mRNA vaccine-proximate (vaccination 0-21 days prior to presentation), remotely vaccinated (vaccinated >21 days prior), and unvaccinated cases. Relative incidence of myocarditis/myopericarditis/pericarditis 0-21 days after vaccination was estimated via a self-controlled case series analysis adjusted for pre-Omicron vs Omicron periods. Cell sizes <5 were suppressed. RESULTS: Overall, 168 cases were included: 73 (43%) vaccine-proximate cases, 47 (28%) remotely vaccinated, 39 (23%) unvaccinated, and 9 (5%) with unknown vaccination status. Among vaccine-proximate cases, 88% (64/73) were male, and 95%-99% (69-72/73) were 12-16 years of age. Among unvaccinated cases, 56% (22/39) were male, and 36% (14/39) were 12-16 years of age. Unvaccinated cases appeared more likely to require intensive care unit care (28% vs <7% of vaccine-proximate cases). The adjusted relative incidence of myocarditis/myopericarditis/pericarditis 0-21 days postvaccination was 7.1 (95% CI 4.5-11.1). CONCLUSIONS: Although myocarditis, myopericarditis, and pericarditis were associated with COVID-19 mRNA vaccination, children with postvaccine myocarditis, myopericarditis, and pericarditis appeared to have a less severe initial course than unvaccinated children.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.005 |
| Science and technology studies | 0.002 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 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".