Clinical study for the identification of factors influencing the immune response to yellow fever and dengue vaccines
Investigation of the immune response to the yellow fever and dengue vaccines in healthy volunteers with or without prior orthoflavivirus immunity
This is an investigation of the immune response to the yellow fever (YF17D) and dengue (QDENGA) vaccines in healthy adult volunteers with or without prior orthoflavivirus immunity in the Veneto Region. Biological fluids (blood, saliva and urine) are collected from study subjects at baseline and during follow-up visits. The study plans to enrol 200 subjects for each vaccination, to include at least 20 individuals with pre-existing immunity to West Nile virus (WNV) or Usutu virus (USUV). Subject recruitment (provision of information and collection of written informed consent) will take place at the Microbiology and Virology Unit of the Padua University Hospital. Data collection includes a detailed medical history and the collection of biological samples (blood, saliva, and urine) at the time of vaccination (T0), during follow-ups at days 14 and 28 post-vaccination, and one year after vaccination. Analyses will include serological tests for IgM and IgG against various orthoflaviviruses, with confirmation by viral neutralization assays, evaluation of cell-mediated response, analysis of viral replication kinetics, and study of predictive biomarkers for adaptive immune response efficacy. Data management involves pseudonymized coding of subjects and anonymous treatment of data in the flow. This study will provide crucial insights into the dynamics of the immune response to orthoflavivirus vaccines, considering the context of pre-existing immunity, with potential significant implications for the development of optimized and personalized vaccination strategies.
1. Male or female individuals aged between 18 and 60 years 2. Healthy individuals, free from acute infections or chronic diseases 3. Willingness to provide written informed consent after being adequately informed about the risks and benefits of the study 4. Availability to participate in at least two study-scheduled visits
1. Hypersensitivity to vaccine components (active ingredients or excipients) for YF17D and QDENGA vaccines, including egg/chicken proteins for YF17D. 2. Severe hypersensitivity reactions to previous yellow fever or dengue vaccines. 3. Immunodeficiency (congenital, idiopathic, or treatment-induced). 4. History of thymic dysfunction. 5. Symptomatic HIV infection or asymptomatic HIV with compromised immune response. 6. Moderate to severe illness or acute disease. 7. Pregnancy or breastfeeding. 8. Body temperature >38°C or acute illness on study entry day. 9. Autoimmune diseases or immunosuppressive therapy within 6 months. 10. Corticosteroid therapy >2 weeks in the past 3 months. 11. Known allergic or anaphylactic reactions. 12. Use of unregistered drugs or participation in other clinical trials. 13. Recent (<3 months) or planned administration of immunoglobulins or blood products. 14. Non-compliance with study objectives or protocol (investigator's opinion). 15. Anticipated absence from the study center during the study period.