Peer-reviewed article
mRNA COVID-19 vaccine safety among children and adolescents: a Canadian National Vaccine Safety Network cohort study
Phyumar Soe, Otto G. Vanderkooi, Manish Sadarangani, Monika Naus, Matthew Paul Muller et al. ·
Summary
Written by AI, not yet AICS's view · claude-haiku-4-5-20251001This Canadian study monitored the safety of mRNA COVID-19 vaccines in children and adolescents aged 6 months to 19 years between January 2021 and February 2023. Most health events reported after vaccination were mild and self-limited, lasting about 7 days. Adolescents reported more health events after the second vaccine dose compared to unvaccinated controls, but younger children showed no difference. Rare cases of myocarditis and pericarditis were reported in male adolescents following the second dose.
Key points
- 259,361 vaccinated and 1,179 unvaccinated children and adolescents participated across eight Canadian provinces and territories
- After dose 2, vaccinated adolescents had higher health event rates (4.6-10.6%) than unvaccinated controls (3.7%), with most events self-limiting within 7 days
- No significant differences in health events were found between vaccinated and unvaccinated groups for children under 5 or aged 5-11 years after any dose
- Myocarditis/pericarditis cases peaked in male adolescents after dose 2: 0.037% for BNT162b2 and 0.529% for mRNA-1273 recipients
- Safety profile varied by pediatric age group, with younger children showing generally better tolerability than adolescents
Limitations
The study captured short-to-medium term safety outcomes only and relied on self-reported health events from participants, which may be subject to recall bias or differential reporting between vaccinated and unvaccinated groups. Long-term safety outcomes beyond the study period are not addressed.
Abstract
Background: The Canadian National Vaccine Safety Network conducted active safety surveillance for COVID-19 vaccines. This study aimed to characterize the short-to-medium term safety of mRNA COVID-19 vaccines across the pediatric age spectrum. Methods: In this cohort study, vaccinated and unvaccinated children and adolescents aged 6 months to 19 years from eight Canadian provinces and territories were invited to participate. The outcome was a health event preventing daily activities, resulting in school absenteeism, or requiring medical consultation. Age-stratified multivariable regression models were used to examine health events associated with first and second doses of mRNA COVID-19 vaccines across different age groups: children under 5, children aged 5-11 years and adolescents aged 12-19 years. Findings: From January 2021 through February 2023, a total of 259,361 individuals from the dose one survey, 131,032 from the dose 2 survey, and 1179 from the control survey were included. In the week following dose two, vaccinated adolescents showed a higher proportion of health events [794 (4.6%) of 17,218 BNT162b2 recipients, 98 (8.5%) of 1153 mRNA-1273 recipients, 49 of (10.6%) of 464 heterologous schedule recipients] than unvaccinated adolescents [9 (3.7%) of 242 controls], but most events were self-limited and resolved within 7 days. No significant differences in proportion of health events following mRNA COVID-19 vaccines were observed between vaccinated and unvaccinated groups among adolescents after dose 1, or among children under 5 or those aged 5-11 years after any dose. Reported myocarditis/pericarditis cases within 0-28 days peaked among male adolescents following dose 2, in three of (0.037%) 8088 homologous BNT162b2 recipients, and two of (0.529%) 378 homologous mRNA-1273 recipients. Interpretation: Our findings suggest that reported health events, including myocarditis/pericarditis, vary by pediatric age group. Vaccinated adolescents reported health events more frequently following the second mRNA COVID-19 vaccine dose, while younger age groups did not report events more frequently than their unvaccinated counterparts. Funding: Canadian Immunization Research Network, Canadian Institutes of Health Research; Public Health Agency of Canada; COVID-19 Immunity Task Force.
Findings the Hub has extracted
Each claim below is labelled by its type of design and links back to this report.
- Intervention
- Administration of mRNA COVID-19 vaccines (BNT162b2 or mRNA-1273), with active safety surveillance monitoring for health events preventing daily activities, causing school absenteeism, or requiring medical consultation
- Population
- Vaccinated (259,361 dose 1; 131,032 dose 2) and unvaccinated (1,179 control) children and adolescents aged 6 months to 19 years across eight Canadian provinces and territories
Key finding
Adolescents post-dose 2: 4.6-10.6% reported health events versus 3.7% in unvaccinated controls, but events were self-limited within 7 days