81 mRNA COVID-19 vaccine safety among children and adolescents from the Canadian National Vaccine Safety Network

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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.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.