81 mRNA COVID-19 vaccine safety among children and adolescents from the Canadian National Vaccine Safety Network
Bibliographic record
Abstract
Abstract Background The Canadian National Vaccine Safety Network (CANVAS) expanded its active safety surveillance for COVID-19 vaccines among children and adolescents during the COVID-19 pandemic. Objectives This analysis aimed to determine whether the first or second dose of mRNA COVID-19 vaccination is associated with health events in children and adolescents. Design/Methods Adolescents 15-19 years of age or parents/guardians of children 5-14 years of age were recruited from seven Canadian provinces/territories and followed for the occurrence of health events seven days after doses 1 and 2 or for a seven-day period for unvaccinated participants. The primary outcome was a health event that prevented daily activities, resulted in school absenteeism, and/or required a medical consultation, including emergency department visits or hospitalization. Aged-stratified multivariable logistic regression examined health events associated with mRNA COVID-19 vaccines (BNT162b2, mRNA1273, and mixed [different products for doses 1 and 2]) for children aged 5 to 11 years and adolescents aged 12 to 19 years. Results Between January 2021 and February 2023, a total of 249,418 (Children BNT162b2: 205,744, mRNA-1273: 36, and Adolescent BNT162b2: 39,628, mRNA-1273: 4,010) completed the first dose survey and 128,599 (Children BNT162b2: 109,625, mRNA-1273: 3, mixed: 235, and Adolescent BNT162b2: 17,202, mRNA-1273: 1,155, mixed: 474) had completed the second dose survey. A total of 668 unvaccinated participants (Children 431 and Adolescent 237) completed the control survey. In the week following dose 1, health event rates among vaccinated children and adolescents were <4% and lower than in unvaccinated counterparts (6.9%), and neither BNT162b2 nor mRNA-1273 were associated with health events in either age group. Following dose 2, among vaccinated adolescents health events rates (BNT162b2 4.6%, mRNA-1273 8.5%, mixed 10.4%) were higher than unvaccinated adolescents (3.4%), but were self-limiting and resolved within 7 days. Among children, there was no difference in health event rates between vaccinated and unvaccinated groups. Conclusion For children, mRNA COVID-19 vaccines were not associated with health events preventing daily activities, resulting in school absenteeism and/or requiring medical consultation. Similar to vaccinated adults our findings found vaccinated adolescents reported higher rates of health events after dose 2 mRNA COVID-19 vaccines, but these were self-limiting and resolved quickly. Our findings can be used to inform adolescents and their parents of what to expect following COVID-19 vaccination.
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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 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".