Active safety surveillance of COVID-19 mRNA vaccines in children aged 5-15 years in Australia

AusVaxSafety (Australia’s active safety surveillance system) used SMS/email delivered surveys to actively solicit the short-term (within first 3 days after vaccination) adverse event profile of mRNA COVID-19 vaccines in children (aged 5–15 years) by age, dose, brand and pre-existing comorbidity. 392,268 survey responses for children aged 5–15 who received a COVID-19 vaccine between July 2021–May 2022 (211,994 following BNT162b2 10mcg in children aged 5–11 years, 173,329 following BNT162b2 30mcg and 6,945 following mRNA-1273 100mcg in adolescents aged 12–15 years) were analysed. Adverse event rates were higher following dose 2 and 3 compared to dose 1 after all vaccines and highest following dose 2 of mRNA-1273 in 12–15 years. Fever was low in the youngest children (5 years old, any dose; 1,090/26,181 (4%)). Medical review rates remained low (0.3% overall) and impact on daily activities was also low (7% overall). No self-reported cases of myocarditis or pericarditis were identified. Ongoing active safety surveillance of lower dose mRNA vaccines in children under 5 years old is required to better understand safety as the vaccines roll out into this population age-group. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement AusVaxSafety surveillance is funded under a contract with the Australian Department of Health. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Human Research Ethics Committee of the Sydney Childrens Hospitals Network gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors * (AEFI) : Adverse event following immunisation