Phase 3 Randomized, Modified Double-blind, Active-controlled Safety Study on vYF in Adults

The purpose of this study is to assess the safety of vYF (investigational vaccine) compared to the safety of YF-VAX (YF licensed vaccine) in adults aged 18 years up to 60 years. Study details include: * The study duration will be up to approximately 6 months. * One single dose of the study intervention (vYF or YF-VAX) will be administered subcutaneously at the 1st visit. * The visit(V) frequency will be Day(D) 01 (V01) and D29 (V02). Two telephone calls will be planned at D15 and Month(M)6. Number of Participants: A total of 640 participants are expected to be included in the study in a 3:1 ratio (vYF: YF-VAX): Group 1: vYF; N=480 Group 2: YF-VAX; N=160 Study Arms and Duration: Randomized, active control (YF-VAX). 6 months duration per participants. Eligible participants will be randomized in a 3:1 ratio to receive, subcutaneously, a single dose of vYF or YF-VAX vaccines on D01.