Retrospective analysis of one year of passive safety surveillance data following implementation of the dengue vaccine, Qdenga® (TAK-003) at private vaccination centers, in Buenos Aires, Argentina

Dengue vaccine Qdenga® has been available in Argentina since November 2023. This study aimed to evaluate adverse events following immunization (AEFI) in individuals vaccinated with Qdenga® in private centers in the metropolitan area of Buenos Aires. A retrospective, observational, multicenter study was conducted through passive surveillance of AEFI in individuals ≥4-years-old who received Qdenga® from 01/Nov/2023 to 01/Nov/2024. AEFI incidence was calculated per 1000 doses administered, stratified by dose, age group and seriousness. Associations between population characteristics and AEFI were analysed. Hypersensitivity reactions incidence was calculated. 156,676 doses were administered to 112,345 individuals, mean age 36.5 years (median 40; range 4–102). A total of 303 AEFI were reported, with an incidence rate of 1.9/1000; 2.5/1000 (277/109,281) for first dose and 0.5/1000 (26/47,395) for second dose. No statistical differences by age and higher reports in 18–60-year-old group women were observed. 1-Non-serious (95.1%): the most frequent were rash (41.8%), myalgia (30.0%), pyrexia (29.2%) and headache (26.0%) after first dose; pyrexia (38.5%) and headache (26.9%) after second dose. 2-Serious (1.3%): anaphylactic reaction, nephrotic syndrome, immune thrombocytopenic purpura, and Hodgkin's lymphoma. 3-Special Situation Reports (2.6%): Five pregnant women vaccinated; one infant born with interventricular communication. Three vaccinated while breastfeeding; one infant had diarrhea. 4-Vaccine administration errors (1.0%): three cases. Anaphylaxis and hypersensitivity non-anaphylaxis incidence: 0.006/1000 and 0.14/1000 respectively. AEFI cases were more common after the first dose and mostly non-serious. No age-related association was found. This study identified few signals in passive surveillance after Qdenga® vaccine. Clinical trial registration number: NCT06898775 • Qdenga® vaccine has been available in Argentina since November 2023. • Private Centers in Buenos Aires vaccinated 112,345 individuals. • One-year analysis of adverse events following immunization (AEFI). • AEFI cases were more frequent after the first dose and predominantly non-serious. • Few safety signals were identified.