Safety of seasonal inactivated influenza vaccines in children 6 months–17 years of age in the Vaccine Adverse Events Reporting System (VAERS) 2018–2023: before, during, and after the COVID-19 pandemic public health emergency

Annual influenza vaccination is recommended for persons aged ≥6 months to prevent influenza illness and its potential complications. Young children are at a higher risk of developing severe influenza. We describe characteristics and reporting of Vaccine Adverse Event Reporting System (VAERS) reports following seasonal inactivated influenza vaccines (IIV) in children aged 6 months–17 years over five influenza seasons spanning the COVID-19 pandemic. We assessed VAERS reports after IIV among children aged 6 months–17 years received during July 1, 2018–June 30, 2023, to describe demographics, clinical characteristics, and trends. Overall reporting rates of AEs after IIV during the earlier and later halves of the analytic period were estimated using FluVaxView IIV doses for children aged 1–17 years. We conducted exploratory empirical Bayesian data mining for disproportionate reporting. Serious reports and adverse events (AEs) of special interest (AESIs) were investigated using Brighton Collaboration and published case definitions. Among 7,815 VAERS pediatric IIV reports, 2,835 (36.3%) were of children aged <5 years; 3,825 (48.9%) were of females; and 326 (4.2%) were serious reports. The reporting rate decreased during the latter half of the analytic period (reporting rate ratio 0.70 [95% CI 0.66–0.73]). IIV was co-administered with another vaccine in 3,535 reports (45.2%); mRNA COVID-19 vaccines were the vaccines most frequently given simultaneously with IIV (1,049 reports, 29.7%). The most commonly reported AEs were injection site erythema (879, 11.2%), fever (689, 8.8%), and syncope (662, 8.5%). Reports of AESIs included anaphylaxis (20, 0.3%), Guillain-Barré Syndrome (10, 0.1%), and among children ≤5 years, febrile seizures (80, 3.0%). During these five influenza seasons, there were no unexpected AEs after pediatric IIV vaccination. Most reports were non-serious (95.8%); reports of injection site erythema, fever, and syncope were consistent with previous studies. VAERS will continue to monitor AEs after influenza vaccination. • Most pediatric influenza vaccine adverse event (AE) reports were non-serious • Among reports, 45.2% of influenza vaccines were administered with another vaccine • COVID-19 vaccines were most commonly co-administered (29.7%) • The most reported AEs overall were injection site erythema (11%), fever (9%), and syncope (9%) • Reported AEs were generally consistent with pre-clinical and post-marketing studies