Adverse events following Synflorix vaccination reported to the Vaccine Adverse Event Reporting System (VAERS), 2010–2024

Age-specific patterns of adverse events following Synflorix vaccination were observed, with infants and toddlers showing higher intensities of systemic reactions. Compared to other pneumococcal vaccines, Synflorix exhibited a relative higher mortality reporting frequency, along with higher frequencies and RORs for specific PTs, including HHE, hypotonia, pallor, and bronchiolitis. Enhanced post-vaccination monitoring is recommended for younger populations due to their immature immune systems. Age-stratified surveillance can help optimize vaccine safety and management.