An active surveillance study of adverse events following to Japanese encephalitis inactivated vaccine (JE-I) in Jiangsu Province, China, 2024-2025

OBJECTIVE: To evaluate the safety of the Japanese Encephalitis Inactivated Vaccine (JE-I) through an active surveillance in Jiangsu Province, China. RESEARCH DESIGN AND METHODS: Active follow-up was conducted among children vaccinated with JE-I from 1 January 2024, to 31 March 2025, and systematically document the occurrence of adverse events following immunization (AEFI). RESULTS: < 0.001).Most cases (84.31%) developed symptoms within one day post-vaccination. Fever was the most common symptom (92.33%). Symptoms were generally mild and transient, resolving without or with minimal intervention. Sixteen children experienced two AEFI episodes, with no aggravation in the second. CONCLUSION: JE-I AEFI incidence in Jiangsu was relatively low, predominantly common reactions. No serious adverse reactions were reported, indicating a favorable safety profile. CLINICAL TRIAL REGISTRATION: www.clinicaltrials.gov identifier is NCT06372665.